Properties of welded joints in laser welding of aeronautic aluminum-lithium alloys

NASA Astrophysics Data System (ADS)

Malikov, A. G.; Orishich, A. M.

2017-01-01

The work presents the experimental investigation of the laser welding of the aluminum-lithium alloys (system Al-Mg-Li) and aluminum alloy (system Al-Cu-Li) doped with Sc. The influence of the nano-structuring of the surface layer welded joint by the cold plastic deformation method on the strength properties of the welded joint is determined. It is founded that, regarding the deformation degree over the thickness, the varying value of the welded joint strength is different for these aluminum alloys.

Particulate and gaseous emissions when welding aluminum alloys.

PubMed

Cole, Homer; Epstein, Seymour; Peace, Jon

2007-09-01

Fabrication and repair of aluminum components and structures commonly involves the use of electric arc welding. The interaction of the arc and the metal being welded generates ultraviolet radiation, metallic oxides, fumes, and gases. Aluminum is seldom used as the pure metal but is often alloyed with other metals to improve strength and other physical properties. Therefore, the exact composition of any emissions will depend on the welding process and the particular aluminum alloy being welded. To quantify such emissions, The Aluminum Association sponsored several studies to characterize arc welding emissions by the gas metal arc welding (GMAW) and gas tungsten arc welding (GTAW) processes for various combinations of base and filler alloys. In all cases, the tests were conducted under conditions that could be found in a production weld shop without forced ventilation. The concentrations of each analyte that a welder could be exposed to were greatly affected by the welding process, the composition of the base and filler alloys, the position of the welder, and the welding helmet. The results obtained can be used by employers to identify and control potential hazards associated with the welding of aluminum alloys and can provide the basis for hazard communication to employees involved in the welding of these alloys.

Filler wire for aluminum alloys and method of welding

NASA Technical Reports Server (NTRS)

Bjorkman, Jr., Gerald W. O. (Inventor); Cho, Alex (Inventor); Russell, Carolyn K. (Inventor)

2003-01-01

A weld filler wire chemistry has been developed for fusion welding 2195 aluminum-lithium. The weld filler wire chemistry is an aluminum-copper based alloy containing high additions of titanium and zirconium. The additions of titanium and zirconium reduce the crack susceptibility of aluminum alloy welds while producing good weld mechanical properties. The addition of silver further improves the weld properties of the weld filler wire. The reduced weld crack susceptibility enhances the repair weldability, including when planishing is required.

Ultrasonic Real-Time Quality Monitoring Of Aluminum Spot Weld Process

NASA Astrophysics Data System (ADS)

Perez Regalado, Waldo Josue

The real-time ultrasonic spot weld monitoring system, introduced by our research group, has been designed for the unsupervised quality characterization of the spot welding process. It comprises the ultrasonic transducer (probe) built into one of the welding electrodes and an electronics hardware unit which gathers information from the transducer, performs real-time weld quality characterization and communicates with the robot programmable logic controller (PLC). The system has been fully developed for the inspection of spot welds manufactured in steel alloys, and has been mainly applied in the automotive industry. In recent years, a variety of materials have been introduced to the automotive industry. These include high strength steels, magnesium alloys, and aluminum alloys. Aluminum alloys have been of particular interest due to their high strength-to-weight ratio. Resistance spot welding requirements for aluminum vary greatly from those of steel. Additionally, the oxide film formed on the aluminum surface increases the heat generation between the copper electrodes and the aluminum plates leading to accelerated electrode deterioration. Preliminary studies showed that the real-time quality inspection system was not able to monitor spot welds manufactured with aluminum. The extensive experimental research, finite element modelling of the aluminum welding process and finite difference modeling of the acoustic wave propagation through the aluminum spot welds presented in this dissertation, revealed that the thermodynamics and hence the acoustic wave propagation through an aluminum and a steel spot weld differ significantly. For this reason, the hardware requirements and the algorithms developed to determine the welds quality from the ultrasonic data used on steel, no longer apply on aluminum spot welds. After updating the system and designing the required algorithms, parameters such as liquid nugget penetration and nugget diameter were available in the ultrasonic data

Gas-tungsten arc welding of aluminum alloys

DOEpatents

Frye, Lowell D.

1984-01-01

A gas-tungsten arc welding method for joining together structures formed of aluminum alloy with these structures disposed contiguously to a heat-damagable substrate of a metal dissimilar to the aluminum alloy. The method of the present invention is practiced by diamond machining the fay surfaces of the aluminum alloy structures to provide a mirror finish thereon having a surface roughness in the order of about one microinch. The fay surfaces are aligned and heated sufficiently by the tungsten electrode to fuse the aluminum alloy contiguous to the fay surfaces to effect the weld joint. The heat input used to provide an oxide-free weld is significantly less than that required if the fay surfaces were prepared by using conventional chemical and mechanical practices.

Gas-tungsten arc welding of aluminum alloys

DOEpatents

Frye, L.D.

1982-03-25

The present invention is directed to a gas-tungsten arc welding method for joining together structures formed of aluminum alloy with these structures disposed contiguously to a heat-damagable substrate of a metal dissimilar to the aluminum alloy. The method of the present invention is practiced by diamond machining the fay surfaces of the aluminum alloy structures to profice a mirror finish thereon having a surface roughness in the order of about one microinch. The fay surface are aligned and heated sufficiently by the tungsten electrode to fuse the aluminum alloy continguous to the fay surfaces to effect the weld joint. The heat input used to provide an oxide-free weld is significantly less than that required if the fay surfaces were prepared by using conventional chemical and mechanical practices.

Aluminum Lithium Alloy 2195 Fusion Welding Improvements with New Filler Wire

NASA Technical Reports Server (NTRS)

Russell, Carolyn; Bjorkman, Gerry; McCool, Carolyn (Technical Monitor)

2000-01-01

A viewgraph presentation outlines NASA Marshall Space Flight Center, Lockheed Martin Michoud Space Systems, and McCook Metals' development an aluminum-copper weld filler wire for fusion welding 2195 aluminum lithium. The aluminum-copper based weld filler wire has been identified as B218, which is the result of six years of weld filler wire development funded by NASA, Lockheed Martin, and McCook Metals. The Super Lightweight External Tank for the NASA Space Shuttle Program consists of 2195 welded with 4043 aluminum-silicon weld filler wire. The B218 filler wire chemistry was developed to produce enhanced 2195 weld and repair weld mechanical properties. An initial characterization of the B218 weld filler wire was performed consisting of initial weld and repair weld evaluation comparing B218 and 4043. The testing involved room temperature and cryogenic tensile testing along with fracture toughness testing. B218 weld filler wire proved to produce enhanced initial and repair weld tensile and fracture properties over 4043. B218 weld filler wire has proved to be a superior weld filler wire for welding 2195 and other aluminum lithium alloys over 4043.

A Method for Welding Sheet Aluminum to SAE 4140 Steel

DTIC Science & Technology

1944-01-01

Restricted Report 4A01 A METHOD FOR WELDING SHEET ALU-M TO SAE 4140 STEEL By W. F. Hess and E. F. Nippes, Jr. Welding Laboratory, Rensselaer Polytechnic...ALUMINUM High strength, duotilo welds of welding ourrent cmdplathg To SAE 4140S !I?EEG Introduction Tho problem of spat wel~ing aluminum to steel was...this procoduro, silver@atod SAE 4140 stool mpeci- mens were preheated to 70(F ~ and rapidly woldod to aluminum, after whioh tho welds were

High-strength laser welding of aluminum-lithium scandium-doped alloys

NASA Astrophysics Data System (ADS)

Malikov, A. G.; Ivanova, M. Yu.

2016-11-01

The work presents the experimental investigation of laser welding of an aluminum alloy (system Al-Mg-Li) and aluminum alloy (system Al-Cu-Li) doped with Sc. The influence of nano-structuring of the surface layer welded joint by cold plastic deformation on the strength properties of the welded joint is determined. It is founded that, regarding the deformation degree over the thickness, the varying value of the welded joint strength is different for these aluminum alloys. The strength of the plastically deformed welded joint, aluminum alloys of the Al-Mg-Li and Al-Cu-Li systems reached 0.95 and 0.6 of the base alloy strength, respectively.

Technology of welding aluminum alloys-I

NASA Technical Reports Server (NTRS)

Harrison, J. R.; Korb, L. J.; Oleksiak, C. E.

1978-01-01

Systems approach to high-quality aluminum welding uses square-butt joints, kept away from sharp contour changes. Intersecting welds are configured for T-type intersections rather than crossovers. Differences in panel thickness are accommodated with transition step areas where thickness increases or decreases within weld, but never at intersection.

FSW of Aluminum Tailor Welded Blanks across Machine Platforms

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hovanski, Yuri; Upadhyay, Piyush; Carlson, Blair

2015-02-16

Development and characterization of friction stir welded aluminum tailor welded blanks was successfully carried out on three separate machine platforms. Each was a commercially available, gantry style, multi-axis machine designed specifically for friction stir welding. Weld parameters were developed to support high volume production of dissimilar thickness aluminum tailor welded blanks at speeds of 3 m/min and greater. Parameters originally developed on an ultra-high stiffness servo driven machine where first transferred to a high stiffness servo-hydraulic friction stir welding machine, and subsequently transferred to a purpose built machine designed to accommodate thin sheet aluminum welding. The inherent beam stiffness, bearingmore » compliance, and control system for each machine were distinctly unique, which posed specific challenges in transferring welding parameters across machine platforms. This work documents the challenges imposed by successfully transferring weld parameters from machine to machine, produced from different manufacturers and with unique control systems and interfaces.« less

Grain fragmentation in ultrasonic-assisted TIG weld of pure aluminum.

PubMed

Chen, Qihao; Lin, Sanbao; Yang, Chunli; Fan, Chenglei; Ge, Hongliang

2017-11-01

Under the action of acoustic waves during an ultrasonic-assisted tungsten inert gas (TIG) welding process, a grain of a TIG weld of aluminum alloy is refined by nucleation and grain fragmentation. Herein, effects of ultrasound on grain fragmentation in the TIG weld of aluminum alloy are investigated via systematic welding experiments of pure aluminum. First, experiments involving continuous and fixed-position welding are performed, which demonstrate that ultrasound can break the grain of the TIG weld of pure aluminum. The microstructural characteristics of an ultrasonic-assisted TIG weld fabricated by fixed-position welding are analyzed. The microstructure is found to transform from plane crystal, columnar crystal, and uniform equiaxed crystal into plane crystal, deformed columnar crystal, and nonuniform equiaxed crystal after application of ultrasound. Second, factors influencing ultrasonic grain fragmentation are investigated. The ultrasonic amplitude and welding current are found to have a considerable effect on grain fragmentation. The degree of fragmentation first increases and then decreases with an increase in ultrasonic amplitude, and it increases with an increase in welding current. Measurement results of the vibration of the weld pool show that the degree of grain fragmentation is related to the intensity of acoustic nonlinearity in the weld pool. The greater the intensity of acoustic nonlinearity, the greater is the degree of grain fragmentation. Finally, the mechanism of ultrasonic grain fragmentation in the TIG weld of pure aluminum is discussed. A finite element simulation is used to simulate the acoustic pressure and flow in the weld pool. The acoustic pressure in the weld pool exceeds the cavitation threshold, and cavitation bubbles are generated. The flow velocity in the weld pool does not change noticeably after application of ultrasound. It is concluded that the high-pressure conditions induced during the occurrence of cavitation, lead to grain

Laser Overlap Welding of Zinc-coated Steel on Aluminum Alloy

NASA Astrophysics Data System (ADS)

Kashani, Hamed Tasalloti; Kah, Paul; Martikainen, Jukka

Local reinforcement of aluminum with laser welded patches of zinc-coated steel can effectively contribute to crashworthiness, durability and weight reduction of car body. However, the weld between Zn-coated steel and aluminum is commonly susceptible to defects such as spatter, cavity and crack. The vaporization of Zn is commonly known as the main source of instability in the weld pool and cavity formation, especially in a lap joint configuration. Cracks are mainly due to the brittle intermetallic compounds growing at the weld interface of aluminum and steel. This study provides a review on the main metallurgical and mechanical concerns regarding laser overlap welding of Zn-coated steel on Al-alloy and the methods used by researchers to avoid the weld defects related to the vaporization of Zn and the poor metallurgical compatibility between steel and aluminum.

Ultrasonic Welding of Thin Alumina and Aluminum Using Inserts

NASA Astrophysics Data System (ADS)

Ishikuro, Tomoaki; Matsuoka, Shin-Ichi

This paper describes an experimental study of ultrasonic welding of thin ceramics and metals using inserts. Ultrasonic welding has enable the joining of various thick ceramics, such as Al2O3 and ZrO2, to aluminum at room temperature quickly and easily as compared to other welding methods. However, for thin ceramics, which are brittle, welding is difficult to perform without causing damage. In this study, aluminum anodized oxide with different anodizing time was used as thin alumina ceramic. Vapor deposition of aluminum alloys was used to create an effective binder layer for welding at a low pressure and within a short duration in order to prevent damage to the anodic oxide film formed with a short anodizing time. For example, ultrasonic welding of thin Al2O3/Al was accomplished under the following conditions: ultrasonic horn tip amplitude of 30µm, welding pressure of 5MPa, and required duration of 0.1s. However, since the vapor deposition film tends to exfoliate as observed in the anodic oxide film formed with a long anodizing time, welding was difficult.

Study of issues in difficult-to-weld thick materials by hybrid laser arc welding

NASA Astrophysics Data System (ADS)

Mazar Atabaki, Mehdi

. The heat and mass transfer and the issues in joining of dissimilar alloys by the hybrid laser/arc welding process (HLAW) were explicitly explained in details. A finite element model was developed to simulate the heat transfer in HLAW of the aluminum alloys. Two double-ellipsoidal heat source models were considered to describe the heat input of the gas metal arc welding and laser welding processes. An experimental procedure was also developed for joining thick advanced high strength steel plates by using the HLAW, by taking into consideration different butt joint configurations. The geometry of the weld groove was optimized according to the requirements of ballistic test, where the length of the softened heat affected zone should be less than 15.9 mm measured from the weld centerline. Since the main issue in HLAW of the AHSS was the formation of the pores, the possible mechanisms of the pores formation and their mitigation methods during the welding process were investigated. Mitigation methods were proposed to reduce the pores inside in the weld area and the influence of each method on the process stability was investigated by an on-line monitoring system of the HLAW process. The groove angle was optimized for the welding process based on the allowed amount of heat input along the TRICLADRTM interface generated by an explosive welding. The weld was fractured in the heat affected zone of the aluminum side in the tensile test. The microharness was shown that the temperature variation caused minor softening in the heat affected zone satisfying the requirement that the width of the softened heat affected zone in the steel side falls within 15.9 mm far away from the weld centerline. The microstructure analysis showed the presence of tempered martensite at the vicinity of the weld area, which it was a cause of softening in the heat affected zone.

The effects of aluminum oxide on inertial welding of aluminum in space applications

NASA Astrophysics Data System (ADS)

Smith, Michael H.

1992-05-01

Inertial friction welding of 2219 aluminum alloy studs to 2219 aluminum alloy plates is investigated in air and in an argon atmosphere to determine the effects of an intact oxide layer on weld quality. Scratch-brushing of plates and studs was performed in an argon atmosphere to break up the oxide layer and prevent reformation prior to testing. Argon was used to simulate the near-oxygen free space environment. Weld quality was determined by a bend test and by measurement of the fraction of the weld surface area that was dimpled in appearance following fracture of the weld. The fundamental theories of friction and wear that are applicable to friction welding are reviewed. A brief survey of current welding methods that may have application in space is presented, as well as a discussion of their feasibility and limitations. Characteristics of the space station are discussed as well as their consequences on welding in space. A qualitative model of the process of inertial friction welding based on the theories of friction and observations of welds and weld fractures is developed and presented.

Microstructural Characterization of Friction Stir Welded Aluminum-Steel Joints

NASA Astrophysics Data System (ADS)

Patterson, Erin E.; Hovanski, Yuri; Field, David P.

2016-06-01

This work focuses on the microstructural characterization of aluminum to steel friction stir welded joints. Lap weld configuration coupled with scribe technology used for the weld tool have produced joints of adequate quality, despite the significant differences in hardness and melting temperatures of the alloys. Common to friction stir processes, especially those of dissimilar alloys, are microstructural gradients including grain size, crystallographic texture, and precipitation of intermetallic compounds. Because of the significant influence that intermetallic compound formation has on mechanical and ballistic behavior, the characterization of the specific intermetallic phases and the degree to which they are formed in the weld microstructure is critical to predicting weld performance. This study used electron backscatter diffraction, energy dispersive spectroscopy, scanning electron microscopy, and Vickers micro-hardness indentation to explore and characterize the microstructures of lap friction stir welds between an applique 6061-T6 aluminum armor plate alloy and a RHA homogeneous armor plate steel alloy. Macroscopic defects such as micro-cracks were observed in the cross-sectional samples, and binary intermetallic compound layers were found to exist at the aluminum-steel interfaces of the steel particles stirred into the aluminum weld matrix and across the interfaces of the weld joints. Energy dispersive spectroscopy chemical analysis identified the intermetallic layer as monoclinic Al3Fe. Dramatic decreases in grain size in the thermo-mechanically affected zones and weld zones that evidenced grain refinement through plastic deformation and recrystallization. Crystallographic grain orientation and texture were examined using electron backscatter diffraction. Striated regions in the orientations of the aluminum alloy were determined to be the result of the severe deformation induced by the complex weld tool geometry. Many of the textures observed in the weld

Influence of groove size and reinforcements addition on mechanical properties and microstructure of friction stir welded joints

NASA Astrophysics Data System (ADS)

Reddy Baridula, Ravinder; Ibrahim, Abdullah Bin; Yahya, Che Ku Mohammad Faizal Bin Che Ku; Kulkarni, Ratnakar; Varma Ramaraju, Ramgopal

2018-03-01

The butt joints fabricated by friction stir welding were found to have more strength than the joints obtained by conventional joining process. The important outcome of this process is the successful fabrication of surface composites with improved properties. Thus in order to further enhance the strength of the dissimilar alloy joints the reinforcements can be deposited in to the aluminium matrix during the process of friction stir welding. In the present study the multi-walled carbon nanotubes were embedded in to the groove by varying the width during joining of dissimilar alloys AA2024 and AA7075. Four widths were selected with constant depth and optimum process parameters were selected to fabricate the sound welded joints. The results show that the mechanical properties of the fabricated butt joints were influenced by the size of the groove, due to variation in the deposition of reinforcement in the stir zone. The microstructural study and identification of the elements of the welded joints show that the reinforcements deposition is influenced by the size of the groove. It has also been observed that the groove with minimum width is more effective than higher width. The mechanical properties are found to be improved due to the pinning of grain boundaries.

Classification of longitudinal welds in an aluminum bridge deck.

DOT National Transportation Integrated Search

2000-01-01

An aluminum bridge deck (called ALUMADECK) has been developed by Reynolds Metal Company and is made of extruded aluminum sections welded together at the sides to form a bridge deck. The longitudinal welds used to connect the extrusions do not match a...

Friction-Stir Welding of Aluminum For the Space Program

NASA Technical Reports Server (NTRS)

Jones, Clyde S.; Smelser, Jerry W. (Technical Monitor)

2002-01-01

The Marshall Space Flight Center is developing and characterizing the friction stir welding process for the Space Shuttle and other space programs. This revolutionary process, invented and patented by The Weld Institute in England, offers tremendous advantages for joining aluminum for high performance applications. It is particularly suited for advanced aluminum-lithium alloys, such as 2195, the primary structural alloy used in the External Tank. The friction stir welding process joins metals with minimal heat input, resulting in high-strength joints with high ductility. It is a simple process to demonstrate using a common milling machine for sample parts, but relatively expensive to implement on large-scale hardware, due to the high cost of tooling needed to handle the high forging pressures characteristic of the process. Recent developments at the Marshall Space Flight Center have demonstrated friction stir welding on linear joints up to 5 meters (15 ft.), with material thickness ranging between 2.5 mm and 16.5 mm (0.100" to 0.650"). High efficiency weld joints have been produced in aluminum from the 2000, 5000, and 6000 series alloy systems. A "retractable pin tool" system was patented by MSFC that allows use of friction stir welding for joints with changing material thickness, and with less rigid tooling than previously considered. This presentation will describe the details of alloys welded to-date and technical advances under development at MSFC. These developments could have substantial benefit to industrial applications for welding aluminum.

NDE and DE of PWSCC Found in the J-Groove Weld of a Removed-From-Service Control Rod Drive Mechanism

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cumblidge, Stephen E.; Doctor, Steven R.; Schuster, George J.

2008-01-01

Studies conducted at the Pacific Northwest National Laboratory (PNNL) in Richland, Washington focused on assessing the effectiveness of nondestructive examination (NDE) techniques for inspecting control rod drive mechanism (CRDM) nozzles and J-groove weldments. The primary objective of this work is to provide information to the United States Nuclear Regulatory Commission (US NRC) on the effectiveness of NDE methods as related to the in-service inspection of CRDM nozzles and J-groove weldments, and to enhance the knowledge base of primary water stress corrosion cracking (PWSCC) through destructive characterization of the CRDM assemblies. Two CRDM assemblies were removed from service, decontaminated, and thenmore » used in a series of laboratory NDE and DE measurements; this report addresses the following questions: 1) What did each NDE technique detect?, 2) What did each NDE technique miss?, 3) How accurately did each NDE technique characterize the detected flaws?, and finally 4) What were the basis for the NDE techniques performance? Two CRDM assemblies including the CRDM nozzle, the J-groove weld, buttering, and a portion of the ferritic head material were selected for this study. This paper focuses on a CRDM assembly that contained suspected PWSCC, based on in-service inspection data and through-wall leakage. The laboratory NDE measurements used to examine the CRDM assembly followed standard industry techniques for conducting in-service inspections of CRDM nozzles and the crown of the J-groove welds and buttering. These techniques included eddy current testing, time of flight diffraction ultrasound, and penetrant testing. In addition, other laboratory-based NDE methods were employed to conduct inspections of the CRDM assembly with particular emphasis on inspecting the J-groove weld and buttering. These techniques included volumetric ultrasonic inspection of the J-groove weld metal, visual testing via replicant material of the J-groove weld and high resolution

Butt Welding Joint of Aluminum Alloy by Space GHTA Welding Process in Vacuum

NASA Astrophysics Data System (ADS)

Suita, Yoshikazu; Shinike, Shuhei; Ekuni, Tomohide; Terajima, Noboru; Tsukuda, Yoshiyuki; Imagawa, Kichiro

Aluminum alloys have been used widely in constructing various space structures including the International Space Station (ISS) and launch vehicles. For space applications, welding experiments on aluminum alloy were performed using the GHTA (Gas Hollow Tungsten Arc) welding process using a filler wire feeder in a vacuum. We investigated the melting phenomenon of the base metal and filler wire, bead formation, and the effects of wire feed speed on melting characteristics. The melting mechanism in the base metal during the bead on a plate with wire feed was similar to that for the melt run without wire feed. We clarified the effects of wire feed speed on bead sizes and configurations. Furthermore, the butt welded joint welded using the optimum wire feed speed, and the joint tensile strengths were evaluated. The tensile strength of the square butt joint welded by the pulsed DC GHTA welding with wire feed in a vacuum is nearly equal to that of the same joint welded by conventional GTA (Gas Tungsten Arc) welding in air.

Integration of NASA-sponsored studies on aluminum welding

NASA Technical Reports Server (NTRS)

Masubuchi, K.

1972-01-01

The results are presented of numerous studies relating to aluminum alloy welding. The subjects covered include: (1) effects of porosity on weld joint performance, (2) sources of porosity, (3) weld thermal effects, (4) residual stresses and distortion, and (5) manufacturing process system control.

Influence of scandium on the microstructure and strength properties of the welded joint at the laser welding of aluminum-lithium alloys

NASA Astrophysics Data System (ADS)

Malikov, A. G.; Golyshev, A. A.; Ivanova, M. Yu.

2017-10-01

Today, aeronautical equipment manufacture involves up-to-date high-strength aluminum alloys of decreased density resulting from lithium admixture. Various technologies of fusible welding of these alloys are being developed. Serious demands are imposed to the welded joints of aluminum alloys in respect to their strength characteristics. The paper presents experimental investigations of the optimization of the laser welding of aluminum alloys with the scandium-modified welded joint. The effect of scandium on the micro-and macro-structure has been studied as well as the strength characteristics of the welded joint. It has been found that scandium under in the laser welding process increases the welded joint elasticity for the system Al-Mg-Li, aluminum alloy 1420 by 20 %, and almost doubles the same for the system Al-Cu-Li, aluminum alloy 1441.

Process Simulation of Gas Metal Arc Welding Software

DOE Office of Scientific and Technical Information (OSTI.GOV)

Murray, Paul E.

2005-09-06

ARCWELDER is a Windows-based application that simulates gas metal arc welding (GMAW) of steel and aluminum. The software simulates the welding process in an accurate and efficient manner, provides menu items for process parameter selection, and includes a graphical user interface with the option to animate the process. The user enters the base and electrode material, open circuit voltage, wire diameter, wire feed speed, welding speed, and standoff distance. The program computes the size and shape of a square-groove or V-groove weld in the flat position. The program also computes the current, arc voltage, arc length, electrode extension, transfer ofmore » droplets, heat input, filler metal deposition, base metal dilution, and centerline cooling rate, in English or SI units. The simulation may be used to select welding parameters that lead to desired operation conditions.« less

Friction stir welding process to repair voids in aluminum alloys

NASA Technical Reports Server (NTRS)

Rosen, Charles D. (Inventor); Litwinski, Edward (Inventor); Valdez, Juan M. (Inventor)

1999-01-01

The present invention provides an in-process method to repair voids in an aluminum alloy, particularly a friction stir weld in an aluminum alloy. For repairing a circular void or an in-process exit hole in a weld, the method includes the steps of fabricating filler material of the same composition or compatible with the parent material into a plug form to be fitted into the void, positioning the plug in the void, and friction stir welding over and through the plug. For repairing a longitudinal void (30), the method includes machining the void area to provide a trough (34) that subsumes the void, fabricating filler metal into a strip form (36) to be fitted into the trough, positioning the strip in the trough, and rewelding the void area by traversing a friction stir welding tool longitudinally through the strip. The method is also applicable for repairing welds made by a fusing welding process or voids in aluminum alloy workpieces themselves.

The microstructure of aluminum A5083 butt joint by friction stir welding

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jasri, M. A. H. M.; Afendi, M.; Ismail, A.

This study presents the microstructure of the aluminum A5083 butt joint surface after it has been joined by friction stir welding (FSW) process. The FSW process is a unique welding method because it will not change the chemical properties of the welded metals. In this study, MILKO 37 milling machine was modified to run FSW process on 4 mm plate of aluminum A5083 butt joint. For the experiment, variables of travel speed and tool rotational speed based on capability of machine were used to run FSW process. The concentrated heat from the tool to the aluminum plate changes the platemore » form from solid to plastic state. Two aluminum plates is merged to become one plate during plastic state and return to solid when concentrated heat is gradually further away. After that, the surface and cross section of the welded aluminum were investigated with a microscope by 400 x multiplication zoom. The welding defect in the FSW aluminum was identified. Then, the result was compared to the American Welding Society (AWS) FSW standard to decide whether the plate can be accepted or rejected.« less

Laser-welded Dissimilar Steel-aluminum Seams for Automotive Lightweight Construction

NASA Astrophysics Data System (ADS)

Schimek, M.; Springer, A.; Kaierle, S.; Kracht, D.; Wesling, V.

By reducing vehicle weight, a significant increase in fuel efficiency and consequently a reduction in CO 2 emissions can be achieved. Currently a high interest in the production of hybrid weld seams between steel and aluminum exists. Previous methods as laser brazing are possible only by using fluxes and additional materials. Laser welding can be used to join steel and aluminum without the use of additives. With a low penetration depth increases in tensile strength can be achieved. Recent results from laser welded overlap seams show that there is no compromise in strength by decreasing penetration depth in the aluminum.

Friction Stir Welding of Thick Section Aluminum for Military Vehicle Applications

DTIC Science & Technology

2012-12-01

Friction Stir Welding of Thick Section Aluminum for Military Vehicle Applications by Brian Thompson, Kevin Doherty, Craig Niese, Mike Eff...International Symposium on Friction Stir Welding (9ISFSW), Huntsville, AL, 15–17 May 2012. Approved for public release...Aberdeen Proving Ground, MD 21005-5069 ARL-RP-417 December 2012 Friction Stir Welding of Thick Section Aluminum for Military

Gas Metal Arc Weld (GMAW) Qualification of 7020-T651 Aluminum

DTIC Science & Technology

2015-11-01

ARL-TR-7515 ● NOV 2015 US Army Research Laboratory Gas Metal Arc Weld (GMAW) Qualification of 7020-T651 Aluminum by John F...Metal Arc Weld (GMAW) Qualification of 7020-T651 Aluminum by John F Chinella Weapons and Materials Research Directorate, ARL Nick Kapustka and...Seth Shira Edison Welding Institute, Columbus, Ohio Approved for public release; distribution is unlimited. ii REPORT

The Mechanical Behavior of Friction-Stir Spot Welded Aluminum Alloys

NASA Astrophysics Data System (ADS)

Güler, Hande

2014-10-01

Aluminum and alloys are widely used in the automotive industry due to the light weight, good formability, and malleability. Spot welding is the most commonly used joining method of these materials, but the high current requirements and the inconsistent quality of the final welds make this process unsuitable. An alternative welding technique, the friction-stir spot welding process, can also be successfully used in joining of aluminum and alloys. In this study, 1-mm-thick AA5754 Al-alloy plates in the H-111 temper conditions were joined by friction-stir spot welding using two different weld parameters such as tool rotational speed and dwell time. Mechanical properties of the joints were obtained with extensive hardness measurements and tensile shear tests. The effect of these parameters on the failure modes of welded joints was also determined.

Weld repair method for aluminum lithium seam

NASA Technical Reports Server (NTRS)

McGee, William Floyd (Inventor); Rybicki, Daniel John (Inventor)

1998-01-01

Aluminum-lithium plates are butt-welded by juxtaposing the plates and making a preliminary weld from the rear or root side of the seam. An initial weld is then made from the face side of the seam, which may cause a defect in the root portion. A full-size X-ray is made and overlain over the seam to identify the defects. The defect is removed from the root side, and rewelded. Material is then removed from the face side, and the cavity is rewelded. The procedure repeats, alternating from the root side to the face side, until the weld is sound.

Gas Contamination In Plasma-Arc-Welded Aluminum

NASA Technical Reports Server (NTRS)

Mcclure, John C.; Torres, Martin R.; Gurevitch, Alan C.; Newman, Robert A.

1992-01-01

Document describes experimental investigation on visible and tactile effects of gaseous contaminants in variable-polarity plasma arc (VPPA) welding of 2219 T-87 aluminum alloy. Contaminant gases (nitrogen, methane, oxygen, and hydrogen) introduced in argon arc and in helium shield gas in various controlled concentrations. Report represents results of experiments in form of photographs of fronts, backs, polished cross sections, and etched cross sections of welds made with various contaminants at various concentrations. Provides detailed discussion of conditions under which welds made.

Exposure assessment of aluminum arc welding radiation.

PubMed

Peng, Chiung-yu; Lan, Cheng-hang; Juang, Yow-jer; Tsao, Ta-ho; Dai, Yu-tung; Liu, Hung-hsin; Chen, Chiou-jong

2007-10-01

The purpose of this study is to evaluate the non-ionizing radiation (NIR) exposure, especially optical radiation levels, and potential health hazard from aluminum arc welding processes based on the American Conference of Governmental Industrial Hygienists (ACGIH) method. The irradiance from the optical radiation emissions can be calculated with various biological effective parameters [i.e., S(lambda), B(lambda), R(lambda)] for NIR hazard assessments. The aluminum arc welding processing scatters bright light with NIR emission including ultraviolet radiation (UVR), visible, and infrared spectra. The UVR effective irradiance (Eeff) has a mean value of 1,100 microW cm at 100 cm distance from the arc spot. The maximum allowance time (tmax) is 2.79 s according to the ACGIH guideline. Blue-light hazard effective irradiance (EBlue) has a mean value of 1840 microW cm (300-700 nm) at 100 cm with a tmax of 5.45 s exposure allowance. Retinal thermal hazard effective calculation shows mean values of 320 mW cm(-2) sr(-1) and 25.4 mW (cm-2) (380-875 nm) for LRetina (spectral radiance) and ERetina (spectral irradiance), respectively. From this study, the NIR measurement from welding optical radiation emissions has been established to evaluate separate types of hazards to the eye and skin simultaneously. The NIR exposure assessment can be applied to other optical emissions from industrial sources. The data from welding assessment strongly suggest employees involved in aluminum welding processing must be fitted with appropriate personal protection devices such as masks and gloves to prevent serious injuries of the skin and eyes upon intense optical exposure.

Analysis and Comparison of Friction Stir Welding and Laser Assisted Friction Stir Welding of Aluminum Alloy

PubMed Central

Campanelli, Sabina Luisa; Casalino, Giuseppe; Casavola, Caterina; Moramarco, Vincenzo

2013-01-01

Friction Stir Welding (FSW) is a solid-state joining process; i.e., no melting occurs. The welding process is promoted by the rotation and translation of an axis-symmetric non-consumable tool along the weld centerline. Thus, the FSW process is performed at much lower temperatures than conventional fusion welding, nevertheless it has some disadvantages. Laser Assisted Friction Stir Welding (LAFSW) is a combination in which the FSW is the dominant welding process and the laser pre-heats the weld. In this work FSW and LAFSW tests were conducted on 6 mm thick 5754H111 aluminum alloy plates in butt joint configuration. LAFSW is studied firstly to demonstrate the weldability of aluminum alloy using that technique. Secondly, process parameters, such as laser power and temperature gradient are investigated in order to evaluate changes in microstructure, micro-hardness, residual stress, and tensile properties. Once the possibility to achieve sound weld using LAFSW is demonstrated, it will be possible to explore the benefits for tool wear, higher welding speeds, and lower clamping force. PMID:28788430

Analysis and Comparison of Friction Stir Welding and Laser Assisted Friction Stir Welding of Aluminum Alloy.

PubMed

Campanelli, Sabina Luisa; Casalino, Giuseppe; Casavola, Caterina; Moramarco, Vincenzo

2013-12-18

Friction Stir Welding (FSW) is a solid-state joining process; i.e. , no melting occurs. The welding process is promoted by the rotation and translation of an axis-symmetric non-consumable tool along the weld centerline. Thus, the FSW process is performed at much lower temperatures than conventional fusion welding, nevertheless it has some disadvantages. Laser Assisted Friction Stir Welding (LAFSW) is a combination in which the FSW is the dominant welding process and the laser pre-heats the weld. In this work FSW and LAFSW tests were conducted on 6 mm thick 5754H111 aluminum alloy plates in butt joint configuration. LAFSW is studied firstly to demonstrate the weldability of aluminum alloy using that technique. Secondly, process parameters, such as laser power and temperature gradient are investigated in order to evaluate changes in microstructure, micro-hardness, residual stress, and tensile properties. Once the possibility to achieve sound weld using LAFSW is demonstrated, it will be possible to explore the benefits for tool wear, higher welding speeds, and lower clamping force.

Blue-Light Hazard From Gas Metal Arc Welding of Aluminum Alloys.

PubMed

Nakashima, Hitoshi; Takahashi, Jyunya; Fujii, Nobuyuki; Okuno, Tsutomu

2017-10-01

The objective was to quantify the blue-light hazard from gas metal arc welding (GMAW) of aluminum alloys. The exposure level is expected to depend on the welding conditions. Therefore, it is important to identify the blue-light hazard under various welding conditions. We experimentally conducted GMAW of aluminum alloys under various welding conditions and measured the spectral radiance of the arcs. The effective blue-light radiance, which the American Conference of Governmental Industrial Hygienists has defined to quantify the exposure level of blue light, was calculated from the measured spectral radiance. The maximum acceptable exposure duration per 10000 s for this effective blue-light radiance was calculated. The effective blue-light radiance measured in this study was in the range of 2.9-20.0 W cm-2·sr. The corresponding maximum acceptable exposure duration per 10000 s was only 5.0-34 s, so it is hazardous to view the welding arc. The effective blue-light radiance was higher at higher welding currents than at lower welding currents, when pulsed welding currents were used rather than steady welding currents, and when magnesium was included in the welding materials. It is very hazardous to view the arcs in GMAW of aluminum alloys. Welders and their helpers should use appropriate eye protection in arc-welding operations. They should also avoid direct light exposure when starting an arc-welding operation. © The Author 2017. Published by Oxford University Press on behalf of the British Occupational Hygiene Society.

GTA welding and heat treating of high purity aluminum. [-452/sup 0/F

DOE Office of Scientific and Technical Information (OSTI.GOV)

Voigt, R.C.; Loper, C.R. Jr.

1979-01-01

Gas tungsten arc welding is a suitable way to join high purity aluminum with only small increases in the electrical resistivity at 4.2 K (i.e., -269 C or -452 F) if proper welding procedures are used. High purity aluminum weld zone properties, useful for the design of cryogenic superconducting devices, are now available. The additional electrical resistivity caused by welding is independent of original base metal resistivity and can be decreased significantly by heat treatments as low as 260 C (500 F) for 30 minutes. Tungsten contamination caused from welding is small (on the order of 0.2 ppM) but itmore » is a significant contribution to weld zone resistivity. This suggests that other welding techniques such as laser welding or electron beam welding may be successful alternatives. Additional GTA welding tests for various welding conditions and welding procedures would lead to a greater understanding of the tungsten emission levels during welding. Perturbations during GTA welding such as electrode spitting or electrode contact with the weld metal must be eliminated to successfully weld high purity aluminum. Improper welding techniques causing arc instabilities, for any reason, cause highly resistive welds that must be properly repaired.« less

Modeling aluminum-lithium alloy welding characteristics

NASA Technical Reports Server (NTRS)

Bernstein, Edward L.

1996-01-01

The purpose of this project was to develop a finite element model of the heat-affected zone in the vicinity of a weld line on a plate in order to determine an accurate plastic strain history. The resulting plastic strain increments calculated by the finite element program were then to be used to calculate the measure of damage D. It was hoped to determine the effects of varying welding parameters, such as beam power, efficiency, and weld speed, and the effect of different material properties on the occurrence of microfissuring. The results were to be compared first to the previous analysis of Inconel 718, and then extended to aluminum 2195.

Effects Of Welding On The Fatigue Behaviour Of Commercial Aluminum AA-1100 Joints

NASA Astrophysics Data System (ADS)

Uthayakumar, M.; Balasubramanian, V.; Rani, Ahmad Majdi Abdul; Hadzima, Branislav

2018-04-01

Friction Stir Welding (FSW) is an budding solid state welding process, which is frequently used for joining aluminum alloys where materials can be joined without melt and recast. Therefore, when welding alloys through FSW the phase transformations occurs will be in the solid state form. The present work is aimed in evaluating the fatigue life of friction stir welded commercial grade aluminum alloy joints. The commercial grade AA1100 aluminum alloy of 12mm thickness plate is welded and the specimens are tested using a rotary beam fatigue testing machine at different stress levels. The stress versus number of cycles (S-N) curves was plotted using the data points. The Fatigue life of tungsten inert gas (TIG) and metal inert gas (MIG) welded joints was compared. The fatigue life of the weld joints was interrelated with the tensile properties, microstructure and micro hardness properties. The effects of the notches and welding processes are evaluated and reported.

A hot-cracking mitigation technique for welding high-strength aluminum alloy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Y.P.; Dong, P.; Zhang, J.

2000-01-01

A hot-cracking mitigation technique for gas tungsten arc welding (GTAW) of high-strength aluminum alloy 2024 is presented. The proposed welding technique incorporates a trailing heat sink (an intense cooling source) with respect to the welding torch. The development of the mitigation technique was based on both detailed welding process simulation using advanced finite element techniques and systematic laboratory experiments. The finite element methods were used to investigate the detailed thermomechanical behavior of the weld metal that undergoes the brittle temperature range (BTR) during welding. As expected, a tensile deformation zone within the material BTR region was identified behind the weldmore » pool under conventional GTA welding process conventional GTA welding process conditions for the aluminum alloy studied. To mitigate hot cracking, the tensile zone behind the weld pool must be eliminated or reduce to a satisfactory level if the weld metal hot ductility cannot be further improved. With detailed computational modeling, it was found that by the introduction of a trailing heat sink at some distance behind the welding arc, the tensile strain rate with respect to temperature in the zone encompassing the BTR region can be significantly reduced. A series of parametric studies were also conducted to derive optimal process parameters for the trailing heat sink. The experimental results confirmed the effectiveness of the trailing heat sink technique. With a proper implementation of the trailing heat sink method, hot cracking can be completely eliminated in welding aluminum alloy 2024 (AA 2024).« less

Heat treatment stabilizes welded aluminum jigs and tool structures

NASA Technical Reports Server (NTRS)

Mehnert, R. S.

1966-01-01

Heat treatment processes, applied after welding but before machining, imparts above normal stability to welded aluminum jigs and tool structures. Weight saving will not be realized in these tools if rigidity equal to that of a comparable steel tool is required.

Renewal of corrosion protection of coated aluminum after welding

NASA Technical Reports Server (NTRS)

Higgins, R. H.

1969-01-01

Effectiveness of conversion coatings designed to protect aluminum alloys against atmospheric corrosion is reduced after exposure to high temperature or welding. Damaged coating should be manually stripped six inches from the weld and then recoated by sponge or spray with the original solution.

New technique of skin embedded wire double-sided laser beam welding

NASA Astrophysics Data System (ADS)

Han, Bing; Tao, Wang; Chen, Yanbin

2017-06-01

In the aircraft industry, double-sided laser beam welding is an approved method for producing skin-stringer T-joints on aircraft fuselage panels. As for the welding of new generation aluminum-lithium alloys, however, this technique is limited because of high hot cracking susceptibility and strengthening elements' uneven distributions within weld. In the present study, a new technique of skin embedded wire double-sided laser beam welding (LBW) has been developed to fabricate T-joints consisting of 2.0 mm thick 2060-T8/2099-T83 aluminum-lithium alloys using eutectic alloy AA4047 filler wire. Necessary dimension parameters of the novel groove were reasonably designed for achieving crack-free welds. Comparisons were made between the new technique welded T-joint and conventional T-joint mainly on microstructure, hot crack, elements distribution features and mechanical properties within weld. Excellent crack-free microstructure, uniform distribution of silicon and superior tensile properties within weld were found in the new skin embedded wire double-sided LBW T-joints.

Technology of welding aluminum alloys-II

NASA Technical Reports Server (NTRS)

1978-01-01

Step-by-step procedures were developed for high integrity manual and machine welding of aluminum alloys. Detailed instructions are given for each step with tables and graphs to specify materials and dimensions. Throughout work sequence, processing procedure designates manufacturing verification points and inspection points.

Thermomechanical treatment of welded joints of aluminum-lithium alloys modified by scandium

NASA Astrophysics Data System (ADS)

Malikov, A. G.

2017-12-01

At present, the aeronautical equipment manufacture involves up-to-date high-strength aluminum alloys of decreased density resulting from the lithium admixture. Various technologies of fusible welding of these alloys are being developed. The paper presents experimental investigations of the optimization of the laser welding of aluminum alloys with the scandium-modified welded joint after thermomechanical treatment. The effect of scandium on the micro- and macrostructure is studied along with strength characteristics of the welded joint. It is found that thermomechanical treatment allows us to obtain the strength of the welded joint 0.89 for the Al-Mg-Li system and 0.99 for the Al-Cu-Li system with the welded joint modified by scandium in comparison with the base alloy after treatment.

Structure formation and properties of a copper-aluminum joint produced by ultrasound-assisted explosive welding

NASA Astrophysics Data System (ADS)

Kuz'min, E. V.; Peev, A. P.; Kuz'min, S. V.; Lysak, V. I.

2017-08-01

The effect of ultrasound-assisted explosive welding on the structure formation and the properties of copper-aluminum joints is studied. Ultrasound-assisted explosive welding improves the quality of formed copper-aluminum joints, i.e., enhances their strength and significantly reduces the amount of fused metal over the entire weldability range. It is shown that ultrasound-assisted explosive welding can noticeably extend the weldability range of the copper-aluminum pair to obtain equal-in-strength joints with minimum structural heterogeneity in the wide welding range.

Weld geometry strength effect in 2219-T87 aluminum

NASA Technical Reports Server (NTRS)

Nunes, A. C., Jr.; Novak, H. L.; Mcilwain, M. C.

1981-01-01

A theory of the effect of geometry on the mechanical properties of a butt weld joint is worked out based upon the soft interlayer weld model. Tensile tests of 45 TIG butt welds and 6 EB beads-on-plate in 1/4-in. 2219-T87 aluminum plate made under a wide range of heat sink and power input conditions are analyzed using this theory. The analysis indicates that purely geometrical effects dominate in determining variations in weld joint strength with heat sink and power input. Variations in weld dimensions with cooling rate are significant as well as with power input. Weld size is suggested as a better indicator of the condition of a weld joint than energy input.

An inelastic analysis of a welded aluminum joint

NASA Astrophysics Data System (ADS)

Vaughan, Robert E.; Schonberg, William P.

1995-02-01

Butt weld joints are most commonly designed into pressure vessels by using weld material properties that are determined from a tensile test. These properties are provided to the stress analyst in the form of a stress vs strain diagram. Variations in properties through the thickness of the weld and along the width of the weld have been suspect but not explored because of inaccessibility and cost. The purpose of this study is to investigate analytical and computational methods used for analysis of multiple pass aluminum 2219-T87 butt welds. The weld specimens are analyzed using classical plasticity theory to provide a basis for modeling the inelastic properties in a finite element solution. The results of the analysis are compared to experimental data to determine the weld behavior and the accuracy of currently available numerical prediction methods.

Optimizing friction stir weld parameters of aluminum and copper using conventional milling machine

NASA Astrophysics Data System (ADS)

Manisegaran, Lohappriya V.; Ahmad, Nurainaa Ayuni; Nazri, Nurnadhirah; Noor, Amirul Syafiq Mohd; Ramachandran, Vignesh; Ismail, Muhammad Tarmizizulfika; Ahmad, Ku Zarina Ku; Daruis, Dian Darina Indah

2018-05-01

The joining of two of any particular materials through friction stir welding (FSW) are done by a rotating tool and the work piece material that generates heat which causes the region near the FSW tool to soften. This in return will mechanically intermix the work pieces. The first objective of this study is to join aluminum plates and copper plates by means of friction stir welding process using self-fabricated tools and conventional milling machine. This study also aims to investigate the optimum process parameters to produce the optimum mechanical properties of the welding joints for Aluminum plates and Copper plates. A suitable tool bit and a fixture is to be fabricated for the welding process. A conventional milling machine will be used to weld the aluminum and copper. The most important parameters to enable the process are speed and pressure of the tool (or tool design and alignment of the tool onto the work piece). The study showed that the best surface finish was produced from speed of 1150 rpm and tool bit tilted to 3°. For a 200mm × 100mm Aluminum 6061 with plate thickness of 2 mm at a speed of 1 mm/s, the time taken to complete the welding is only 200 seconds or equivalent to 3 minutes and 20 seconds. The Copper plates was successfully welded using FSW with tool rotation speed of 500 rpm, 700 rpm, 900 rpm, 1150 rpm and 1440 rpm and with welding traverse rate of 30 mm/min, 60 mm/min and 90 mm/min. As the conclusion, FSW using milling machine can be done on both Aluminum and Copper plates, however the weld parameters are different for the two types of plates.

Analysis and Comparison of Aluminum Alloy Welded Joints Between Metal Inert Gas Welding and Tungsten Inert Gas Welding

NASA Astrophysics Data System (ADS)

Zhao, Lei; Guan, Yingchun; Wang, Qiang; Cong, Baoqiang; Qi, Bojin

2015-09-01

Surface contamination usually occurs during welding processing and it affects the welds quality largely. However, the formation of such contaminants has seldom been studied. Effort was made to study the contaminants caused by metal inert gas (MIG) welding and tungsten inert gas (TIG) welding processes of aluminum alloy, respectively. SEM, FTIR and XPS analysis was carried out to investigate the microstructure as well as surface chemistry. These contaminants were found to be mainly consisting of Al2O3, MgO, carbide and chromium complexes. The difference of contaminants between MIG and TIG welds was further examined. In addition, method to minimize these contaminants was proposed.

High-power Laser Welding of Thick Steel-aluminum Dissimilar Joints

NASA Astrophysics Data System (ADS)

Lahdo, Rabi; Springer, André; Pfeifer, Ronny; Kaierle, Stefan; Overmeyer, Ludger

According to the Intergovernmental Panel on Climate Change (IPCC), a worldwide reduction of CO2-emissions is indispensable to avoid global warming. Besides the automotive sector, lightweight construction is also of high interest for the maritime industry in order to minimize CO2-emissions. Using aluminum, the weight of ships can be reduced, ensuring lower fuel consumption. Therefore, hybrid joints of steel and aluminum are of great interest to the maritime industry. In order to provide an efficient lap joining process, high-power laser welding of thick steel plates (S355, t = 5 mm) and aluminum plates (EN AW-6082, t = 8 mm) is investigated. As the weld seam quality greatly depends on the amount of intermetallic phases within the joint, optimized process parameters and control are crucial. Using high-power laser welding, a tensile strength of 10 kN was achieved. Based on metallographic analysis, hardness tests, and tensile tests the potential of this joining method is presented.

Microprobe investigation of brittle segregates in aluminum MIG and TIG welds

NASA Technical Reports Server (NTRS)

Larssen, P. A.; Miller, E. L.

1968-01-01

Quantitative microprobe analysis of segregated particles in aluminum MIG /Metal Inert Gas/ and TIG /Tungsten Inert Gas/ welds indicated that there were about ten different kinds of particles, corresponding to ten different intermetallic compounds. Differences between MIG and TIG welds related to the individual cooling rates of these welds.

A new technique for the strengthening of aluminum tungsten inert gas weld metals: using carbon nanotube/aluminum composite as a filler metal.

PubMed

Fattahi, M; Nabhani, N; Rashidkhani, E; Fattahi, Y; Akhavan, S; Arabian, N

2013-01-01

The effect of multi-walled carbon nanotube (MWCNT) on the mechanical properties of aluminum multipass weld metal prepared by the tungsten inert gas (TIG) welding process was investigated. High energy ball milling was used to disperse MWCNT in the aluminum powder. Carbon nanotube/aluminum composite filler metal was fabricated for the first time by hot extrusion of ball-milled powders. After welding, the tensile strength, microhardness and MWCNT distribution in the weld metal were investigated. The test results showed that the tensile strength and microhardness of weld metal was greatly increased when using the filler metal containing 1.5 wt.% MWCNT. Therefore, according to the results presented in this paper, it can be concluded that the filler metal containing MWCNT can serve as a super filler metal to improve the mechanical properties of TIG welds of Al and its alloys. Copyright © 2013 Elsevier Ltd. All rights reserved.

Welding Experiments of Aluminum Alloy by Space GHTA Welding at ISS Orbital Pressure

NASA Astrophysics Data System (ADS)

Suita, Yoshikazu; Takai, Daisuke; Sugiyama, Satoshi; Terajima, Noboru; Tsukuda, Yoshiyuki; Fujisawa, Shoichiro; Imagawa, Kichiro

As a feasible welding method in space, the authors previously proposed the space GHTA (Gas Hollow Tungsten Arc) welding process. However, space GHTA welding with a high-frequency device for arc start may cause electromagnetic noise problems for the computer equipment placed on the ISS (International Space Station). Therefore, in this report, welding experiments of space GHTA welding using aluminum alloy with a high-voltage DC device for arc start were carried out at the ISS orbital pressure, 10-5 Pa. It is clear from the experiments using a high-voltage DC device in a high-vacuum condition, that there is a shifting phenomenon in which the spark discharge shifts to either a glow discharge or an arc discharge when starting the arc. Welding projects in space need an arc discharge, so we investigated the effects of welding parameters on the arc formation ratio. As a result, space GHTA welding with a high-voltage DC device can be used for arc start when welding at the ISS orbital pressure.

Study of aluminum content in a welding metal by thermoelectric measurements

NASA Astrophysics Data System (ADS)

Carreón, H.; Ramirez, S.; Coronado, C.; Salazar, M.

2018-03-01

This work investigates the effect caused by the aluminum content in a welding metal and its variation in mechanical properties through the use of a non-destructive thermoelectric technique. It is known that aluminum has positive effects as deoxidizer in low percentages and alloying element together with Niobium and Vanadium. Aluminum has a positive and negative effect, initially improves the mechanical properties of the metal, as it acts as a grain refiner, increasing the yield strength, but in larger quantities, important mechanical properties such as hardness and toughness are seriously affected. For this purpose, HSLA ASTM 572 Gr. 50 steel was used as the base metal, where the weld metal was deposited, after which the specimens were fabricated and the mechanical tests and non-destructive tests were carried out. The sensitivity of the thermoelectric potential technique to microstructural and chemical composition changes was confirmed. The evolution of absolute thermoelectric potential (TEP) values with respect to the percentage of aluminum added to the weld was observed, being also quite sensitive to defects such as micro-cracks.

Welding Experiments of Aluminum Alloy by Space GHTA Welding in the ISS Orbital Pressure

NASA Astrophysics Data System (ADS)

Suita, Yoshikazu; Takai, Daisuke; Sugiyama, Satoshi; Terajima, Noboru; Tsukuda, Yoshiyuki; Fujisawa, Shoichiro; Imagawa, Kichiro

As a feasible welding method in space, the authors have previously proposed the space GHTA (Gas Hollow Tungsten Arc) welding process. The space GHTA welding with high frequency power source for the arc starting may cause the electro-magnetic noise problems of computer equipments placed on the ISS. Therefore, in this paper the welding experiments of aluminum alloy by the space GHTA welding with DC high voltage power source for the arc starting was carried out in the ISS orbital pressure 10-5Pa. It is made clear that there is the shifting phenomenon in which the spark discharge changes to the glow or arc discharge at starting phenomenon of the space GHTA welding in high vacuum condition, and the features of those starting phenomenon are demonstrated. And the space GHTA welding with DC high voltage power source can be used for welding in the ISS orbital pressure.

Self-Reacting Friction Stir Welding for Aluminum Complex Curvature Applications

NASA Technical Reports Server (NTRS)

Brown, Randy J.; Martin, W.; Schneider, J.; Hartley, P. J.; Russell, Carolyn; Lawless, Kirby; Jones, Chip

2003-01-01

This viewgraph representation provides an overview of sucessful research conducted by Lockheed Martin and NASA to develop an advanced self-reacting friction stir technology for complex curvature aluminum alloys. The research included weld process development for 0.320 inch Al 2219, sucessful transfer from the 'lab' scale to the production scale tool and weld quality exceeding strenght goals. This process will enable development and implementation of large scale complex geometry hardware fabrication. Topics covered include: weld process development, weld process transfer, and intermediate hardware fabrication.

Friction Stir Weld Failure Mechanisms in Aluminum-Armor Structures Under Ballistic Impact Loading Conditions

DTIC Science & Technology

2013-01-01

REPORT Friction Stir Weld Failure Mechanisms in Aluminum -Armor Structures Under Ballistic Impact Loading Conditions 14. ABSTRACT 16. SECURITY...Stir Weld Failure Mechanisms in Aluminum -Armor Structures Under Ballistic Impact Loading Conditions M. Grujicic, B. Pandurangan, A. Arakere, C-F. Yen...K.O. Pedersen, Fracture Mechanisms of Aluminum Alloy AA7075-T651 Under Various Loading Conditions , Int. J. Impact Eng., 2010, 37, p 537–551 24. T

Fine-tuned Remote Laser Welding of Aluminum to Copper with Local Beam Oscillation

NASA Astrophysics Data System (ADS)

Fetzer, Florian; Jarwitz, Michael; Stritt, Peter; Weber, Rudolf; Graf, Thomas

Local beam oscillation in remote laser welding of aluminum to copper was investigated. Sheets of 1 mm thickness were welded in overlap configuration with aluminum as top material. The laser beam was scanned in a sinusoidal mode perpendicular to the direction of feed and the influence of the oscillation parameters frequency and amplitude on the weld geometry was investigated. Scanning frequencies up to 1 kHz and oscillation amplitudes in the range from 0.25 mm to 1 mm were examined. Throughout the experiments the laser power and the feed rate were kept constant. A decrease of welding depth with amplitude and frequency is found. The scanning amplitude had a strong influence and allowed coarse setting of the welding depth into the lower material, while the frequency allowed fine tuning in the order of 10% of the obtained depth. The oscillation parameters were found to act differently on the aluminum sheet compared to copper sheet regarding the amount of fused material. It is possible to influence the geometry of the fused zones separately for both sheets. Therefore the average composition in the weld can be set with high precision via the oscillation parameters. A setting of the generated intermetallics in the weld zone is possible without adjustment of laser power and feed rate.

Friction Pull Plug Welding in Aluminum Alloys

NASA Technical Reports Server (NTRS)

Brooke, Shane A.; Bradford, Vann

2012-01-01

NASA's Marshall Space Flight Center (MSFC) has recently invested much time and effort into the process development of Friction Pull Plug Welding (FPPW). FPPW, is a welding process similar to Friction Push Plug Welding in that, there is a small rotating part (plug) being spun and simultaneously pulled (forged) into a larger part. These two processes differ, in that push plug welding requires an internal reaction support, while pull plug welding reacts to the load externally. FPPW was originally conceived as a post proof repair technique for the Space Shuttle fs External Tank. FPPW was easily selected as the primary weld process used to close out the termination hole on the Constellation Program's ARES I Upper Stage circumferential Self-Reacting Friction Stir Welds (SR-FSW). The versatility of FPPW allows it to also be used as a repair technique for both SR-FSW and Conventional Friction Stir Welds. To date, all MSFC led development has been concentrated on aluminum alloys (2195, 2219, and 2014). Much work has been done to fully understand and characterize the process's limitations. A heavy emphasis has been spent on plug design, to match the various weldland thicknesses and alloy combinations. This presentation will summarize these development efforts including weld parameter development, process control, parameter sensitivity studies, plug repair techniques, material properties including tensile, fracture and failure analysis.

Microstructures and Mechanical Properties of Friction Stir Spot Welded Aluminum Alloy AA2014

NASA Astrophysics Data System (ADS)

Babu, S.; Sankar, V. S.; Janaki Ram, G. D.; Venkitakrishnan, P. V.; Madhusudhan Reddy, G.; Prasad Rao, K.

2013-01-01

Friction stir spot welding (FSSW) is a relatively recent development, which can provide a superior alternative to resistance spot welding and riveting for fabrication of aluminum sheet metal structures. In the current work, FSSW experiments were conducted in 3-mm thick sheets of aluminum alloy 2014 in T4 and T6 conditions, with and without Alclad layers. The effects of tool geometry and welding process parameters on joint formation were investigated. A good correlation between process parameters, bond width, hook height, joint strength, and fracture mode was observed. The presence of Alclad layers and the base metal temper condition were found to have no major effect on joint formation and joint strength. Friction stir spot welds produced under optimum conditions were found to be superior to riveted joints in lap-shear and cross-tension tests. The prospects of FSSW in aluminum sheet metal fabrication are discussed.

Corrosion Properties of Dissimilar Friction Stir Welded 6061 Aluminum and HT590 Steel

NASA Astrophysics Data System (ADS)

Seo, Bosung; Song, Kuk Hyun; Park, Kwangsuk

2018-05-01

Corrosion properties of dissimilar friction stir welded 6061 aluminum and HT590 steel were investigated to understand effects of galvanic corrosion. As cathode when coupled, HT590 was cathodically protected. However, the passivation of AA6061 made the aluminum alloy cathode temporarily, which leaded to corrosion of HT590. From the EIS analysis showing Warburg diffusion plot in Nyquist plots, it can be inferred that the stable passivation layer was formed on AA6061. However, the weld as well as HT590 did not show Warburg diffusion plot in Nyquist plots, suggesting that there was no barrier for corrosion or even if it exists, the barrier had no function for preventing and/or retarding charge transport through the passivation layer. The open circuit potential measurements showed that the potential of the weld was similar to that of HT590, which lied in the pitting region for AA6061, making the aluminum alloy part of the weld keep corrosion state. That resulted in the cracked oxide film on AA6061 of the weld, which could not play a role of corrosion barrier.

Improved microstructure and mechanical properties in gas tungsten arc welded aluminum joints by using graphene nanosheets/aluminum composite filler wires.

PubMed

Fattahi, M; Gholami, A R; Eynalvandpour, A; Ahmadi, E; Fattahi, Y; Akhavan, S

2014-09-01

In the present study, different amounts of graphene nanosheets (GNSs) were added to the 4043 aluminum alloy powders by using the mechanical alloying method to produce the composite filler wires. With each of the produced composite filler wires, one all-weld metal coupon was welded using the gas tungsten arc (GTA) welding process. The microstructure, mechanical properties and fracture surface morphology of the weld metals have been evaluated and the results are compared. As the amount of GNSs in the composition of filler wire is increased, the microstructure of weld metal was changed from the dendritic structure to fine equiaxed grains. Furthermore, the tensile strength and microhardness of weld metal was improved, and is attributed to the augmented nucleation and retarded growth. From the results, it was seen that the GNSs/Al composite filler wire can be used to improve the microstructure and mechanical properties of GTA weld metals of aluminum and its alloys. Copyright © 2014 Elsevier Ltd. All rights reserved.

Friction Pull Plug Welding in Aluminum Alloys

NASA Technical Reports Server (NTRS)

Brooke, Shane A.; Bradford, Vann; Burkholder, Jonathon

2011-01-01

NASA fs Marshall Space Flight Center (MSFC) has recently invested much time and effort into the process development of Friction Pull Plug Welding (FPPW). FPPW, is a welding process similar to Friction Push Plug Welding in that, there is a small rotating part (plug) being spun and simultaneously pulled (forged) into a larger part. These two processes differ, in that push plug welding requires an internal reaction support, while pull plug welding reacts to the load externally. FPPW was originally conceived as a post proof repair technique for External Tank. FPPW was easily selected as the primary process used to close out the termination hole on the Constellation Program fs ARES I Upper Stage circumferential Self ] Reacting Friction Stir Welds (SR ]FSW). The versatility of FPPW allows it to also be used as a repair technique for both SR ]FSW and Conventional Friction Stir Welds. To date, all MSFC led development has been concentrated on aluminum alloys (2195, 2219, and 2014). Much work has been done to fully understand and characterize the process fs limitations. A heavy emphasis has been spent on plug design, to match the various weldland thicknesses and alloy combinations. This presentation will summarize these development efforts including weld parameter development, process control, parameter sensitivity studies, plug repair techniques, material properties including tensile, fracture and failure analysis.

Tool For Friction Stir Tack Welding of Aluminum Alloys

NASA Technical Reports Server (NTRS)

Bjorkman, Gerald W.; Dingler, Johnny W.; Loftus, Zachary

2003-01-01

A small friction-stir-welding tool has been developed for use in tack welding of aluminum-alloy workpieces. It is necessary to tack-weld the workpieces in order to hold them together during friction stir welding because (1) in operation, a full-size friction-stir-welding tool exerts a large force that tends to separate the workpieces and (2) clamping the workpieces is not sufficient to resist this force. It is possible to tack the pieces together by gas tungsten arc welding, but the process can be awkward and time-consuming and can cause sufficient damage to necessitate rework. Friction stir tack welding does not entail these disadvantages. In addition, friction stir tack welding can be accomplished by use of the same automated equipment (except for the welding tool) used in subsequent full friction stir welding. The tool for friction stir tack welding resembles the tool for full friction stir welding, but has a narrower shoulder and a shorter pin. The shorter pin generates a smaller workpiece-separating force so that clamping suffices to keep the workpieces together. This tool produces a continuous or intermittent partial-penetration tack weld. The tack weld is subsequently consumed by action of the larger tool used in full friction stir welding tool.

An inelastic analysis of a welded aluminum joint

NASA Astrophysics Data System (ADS)

Vaughan, R. E.

1994-09-01

Butt-weld joints are most commonly designed into pressure vessels which then become as reliable as the weakest increment in the weld chain. In practice, weld material properties are determined from tensile test specimen and provided to the stress analyst in the form of a stress versus strain diagram. Variations in properties through the thickness of the weld and along the width of the weld have been suspect but not explored because of inaccessibility and cost. The purpose of this study is to investigate analytical and computational methods used for analysis of welds. The weld specimens are analyzed using classical elastic and plastic theory to provide a basis for modeling the inelastic properties in a finite-element solution. The results of the analysis are compared to experimental data to determine the weld behavior and the accuracy of prediction methods. The weld considered in this study is a multiple-pass aluminum 2219-T87 butt weld with thickness of 1.40 in. The weld specimen is modeled using the finite-element code ABAQUS. The finite-element model is used to produce the stress-strain behavior in the elastic and plastic regimes and to determine Poisson's ratio in the plastic region. The value of Poisson's ratio in the plastic regime is then compared to experimental data. The results of the comparisons are used to explain multipass weld behavior and to make recommendations concerning the analysis and testing of welds.

An inelastic analysis of a welded aluminum joint

NASA Technical Reports Server (NTRS)

Vaughan, R. E.

1994-01-01

Butt-weld joints are most commonly designed into pressure vessels which then become as reliable as the weakest increment in the weld chain. In practice, weld material properties are determined from tensile test specimen and provided to the stress analyst in the form of a stress versus strain diagram. Variations in properties through the thickness of the weld and along the width of the weld have been suspect but not explored because of inaccessibility and cost. The purpose of this study is to investigate analytical and computational methods used for analysis of welds. The weld specimens are analyzed using classical elastic and plastic theory to provide a basis for modeling the inelastic properties in a finite-element solution. The results of the analysis are compared to experimental data to determine the weld behavior and the accuracy of prediction methods. The weld considered in this study is a multiple-pass aluminum 2219-T87 butt weld with thickness of 1.40 in. The weld specimen is modeled using the finite-element code ABAQUS. The finite-element model is used to produce the stress-strain behavior in the elastic and plastic regimes and to determine Poisson's ratio in the plastic region. The value of Poisson's ratio in the plastic regime is then compared to experimental data. The results of the comparisons are used to explain multipass weld behavior and to make recommendations concerning the analysis and testing of welds.

Friction stir welding of T joints of dissimilar aluminum alloy: A review

NASA Astrophysics Data System (ADS)

Thakare, Shrikant B.; Kalyankar, Vivek D.

2018-04-01

Aluminum alloys are preferred in the mechanical design due to their advantages like high strength, good corrosion resistance, low density and good weldability. In various industrial applications T joints configuration of aluminum alloys are used. In different fields, T joints having skin (horizontal sheet) strengthen by stringers (vertical sheets) were used to increase the strength of structure without increasing the weight. T joints are usually carried out by fusion welding which has limitations in joining of aluminum alloy due to significant distortion and metallurgical defects. Some aluminum alloys are even non weldable by fusion welding. The friction stir welding (FSW) has an excellent replacement of conventional fusion welding for T joints. In this article, FSW of T joints is reviewed by considering aluminum alloy and various joint geometries for defect analysis. The previous experiments carried out on T joints shows the factors such as tool geometry, fixturing device and joint configurations plays significant role in defect free joints. It is essential to investigate the material flow during FSW to know joining mechanism and the formation of joint. In this study the defect occurred in the FSW are studied for various joint configurations and parameters. Also the effect of the parameters and defects occurs on the tensile strength are studied. It is concluded that the T-joints of different joint configurations can be pretended successfully. Comparing to base metal some loss in tensile strength was observed in the weldments as well as overall reduction of the hardness in the thermos mechanically affected zone also observed.

Characteristics of Extra Narrow Gap Weld of HSLA Steel Welded by Single-Seam per Layer Pulse Current GMA Weld Deposition

NASA Astrophysics Data System (ADS)

Agrawal, B. P.; Ghosh, P. K.

2017-03-01

Butt weld joints are produced using pulse current gas metal arc welding process by employing the technique of centrally laid multi-pass single-seam per layer weld deposition in extra narrow groove of thick HSLA steel plates. The weld joints are prepared by using different combination of pulse parameters. The selection of parameter of pulse current gas metal arc welding is done considering a summarized influence of simultaneously interacting pulse parameters defined by a dimensionless hypothetical factor ϕ. The effect of diverse pulse parameters on the characteristics of weld has been studied. Weld joint is also prepared by using commonly used multi-pass multi-seam per layer weld deposition in conventional groove. The extra narrow gap weld joints have been found much superior to the weld joint prepared by multi-pass multi-seam per layer deposition in conventional groove with respect to its metallurgical characteristics and mechanical properties.

Aluminum and stainless steel tubes joined by simple ring and welding process

NASA Technical Reports Server (NTRS)

Townhill, A.

1967-01-01

Duranel ring is used to join aluminum and stainless steel tubing. Duranel is a bimetal made up of roll-bonded aluminum and stainless steel. This method of joining the tubing requires only two welding operations.

Research on the welding process of aluminum alloy based on high power fiber laser

NASA Astrophysics Data System (ADS)

Zhang, Jian; Zhang, Wei; Pan, Xiaoming; Huang, Shanshi; Liu, Wenwen

2017-08-01

To research the formation and variation principle of the weld seam and molten pool for aluminum alloy high power fiber laser welding, the welding experiments for 5052 aluminum alloy were carried out. The influences of laser power, scanning velocity and protection gas on the welding process were systematically researched. The results show that with the increase of power and scanning velocity, the depth to width ratio first increases and then decreases. The ratio reaches the maximum value at 2.6 KW and 30 mm/s, respectively. When the power located at 2.6 KW to 2.8 KW or the velocity located at 25 mm/s to 30 mm/s, stable deep penetration welding can be obtained. The weld seam shows relative flat appearance and the molten pool presents typical "T shape" topography. Moreover, the protection gas also influences the appearance of the weld seam. Using the independently designed fixture, the quality of the weld seam can be well improved.

Fabrication of Aluminum Tubes Filled with Aluminum Alloy Foam by Friction Welding.

PubMed

Hangai, Yoshihiko; Nakano, Yukiko; Koyama, Shinji; Kuwazuru, Osamu; Kitahara, Soichiro; Yoshikawa, Nobuhiro

2015-10-23

Aluminum foam is usually used as the core of composite materials by combining it with dense materials, such as in Al foam core sandwich panels and Al-foam-filled tubes, owing to its low tensile and bending strengths. In this study, all-Al foam-filled tubes consisting of ADC12 Al-Si-Cu die-cast aluminum alloy foam and a dense A1050 commercially pure Al tube with metal bonding were fabricated by friction welding. First, it was found that the ADC12 precursor was firmly bonded throughout the inner wall of the A1050 tube without a gap between the precursor and the tube by friction welding. No deformation of the tube or foaming of the precursor was observed during the friction welding. Next, it was shown that by heat treatment of an ADC12-precursor-bonded A1050 tube, gases generated by the decomposition of the blowing agent expand the softened ADC12 to produce the ADC12 foam interior of the dense A1050 tube. A holding time during the foaming process of approximately t H = 8.5 min with a holding temperature of 948 K was found to be suitable for obtaining a sound ADC12-foam-filled A1050 tube with sufficient foaming, almost uniform pore structures over the entire specimen, and no deformation or reduction in the thickness of the tube.

Fabrication of Aluminum Tubes Filled with Aluminum Alloy Foam by Friction Welding

PubMed Central

Hangai, Yoshihiko; Nakano, Yukiko; Koyama, Shinji; Kuwazuru, Osamu; Kitahara, Soichiro; Yoshikawa, Nobuhiro

2015-01-01

Aluminum foam is usually used as the core of composite materials by combining it with dense materials, such as in Al foam core sandwich panels and Al-foam-filled tubes, owing to its low tensile and bending strengths. In this study, all-Al foam-filled tubes consisting of ADC12 Al-Si-Cu die-cast aluminum alloy foam and a dense A1050 commercially pure Al tube with metal bonding were fabricated by friction welding. First, it was found that the ADC12 precursor was firmly bonded throughout the inner wall of the A1050 tube without a gap between the precursor and the tube by friction welding. No deformation of the tube or foaming of the precursor was observed during the friction welding. Next, it was shown that by heat treatment of an ADC12-precursor-bonded A1050 tube, gases generated by the decomposition of the blowing agent expand the softened ADC12 to produce the ADC12 foam interior of the dense A1050 tube. A holding time during the foaming process of approximately tH = 8.5 min with a holding temperature of 948 K was found to be suitable for obtaining a sound ADC12-foam-filled A1050 tube with sufficient foaming, almost uniform pore structures over the entire specimen, and no deformation and minimum reduction in the thickness of the tube. PMID:28793629

Summary of Results of Tests Made by Aluminum Research Laboratories of Spot-welded Joints and Structural Elements

NASA Technical Reports Server (NTRS)

HARTMANN E C; Stickley, G W

1942-01-01

Available information concerning spot welding as a means of joining aluminum-alloy parts has been summarized and comparisons have been made of the relative merits of spot-welded and riveted aluminum-alloy structural elements. The results indicated that spot welding was as satisfactory as riveting insofar as resistance to static loads is concerned. Spot welds showed slightly lower resistance to impact loads but definitely lower resistance to repeated loads than rivets.

Automatic Welding System of Aluminum Pipe by Monitoring Backside Image of Molten Pool Using Vision Sensor

NASA Astrophysics Data System (ADS)

Baskoro, Ario Sunar; Kabutomori, Masashi; Suga, Yasuo

An automatic welding system using Tungsten Inert Gas (TIG) welding with vision sensor for welding of aluminum pipe was constructed. This research studies the intelligent welding process of aluminum alloy pipe 6063S-T5 in fixed position and moving welding torch with the AC welding machine. The monitoring system consists of a vision sensor using a charge-coupled device (CCD) camera to monitor backside image of molten pool. The captured image was processed to recognize the edge of molten pool by image processing algorithm. Neural network model for welding speed control were constructed to perform the process automatically. From the experimental results it shows the effectiveness of the control system confirmed by good detection of molten pool and sound weld of experimental result.

Effect of Shielding Gas on the Properties of AW 5083 Aluminum Alloy Laser Weld Joints

NASA Astrophysics Data System (ADS)

Vyskoč, Maroš; Sahul, Miroslav; Sahul, Martin

2018-04-01

The paper deals with the evaluation of the shielding gas influence on the properties of AW 5083 aluminum alloy weld joints produced with disk laser. Butt weld joints were produced under different shielding gas types, namely Ar, He, Ar + 5 vol.% He, Ar + 30 vol.% He and without shielding weld pool. Light and electron microscopy, computed tomography, microhardness measurements and tensile testing were used for evaluation of weld joint properties. He-shielded weld joints were the narrowest ones. On the other hand, Ar-shielded weld joints exhibited largest weld width. The choice of shielding gas had significant influence on the porosity level of welds. The lowest porosity was observed in weld joint produced in Ar with the addition of 5 vol.% He shielding atmosphere (only 0.03%), while the highest level of porosity was detected in weld joint produced in pure He (0.24%). Except unshielded aluminum alloy weld joint, the lowest tensile strength was recorded in He-shielded weld joints. On the contrary, the highest average microhardness was measured in He-shielded weld joints.

Effect of the Grain Size of the Initial Structure of 1565chM Alloy on the Structure and Properties of the Joints Fabricated by Friction Stir Welding

NASA Astrophysics Data System (ADS)

Ovchinnikov, V. V.; Drits, A. M.; Gureeva, M. A.; Malov, D. V.

2017-12-01

The effect of the initial grain size in the structure of the aluminum 1565chM alloy on the mechanical properties of the welded joints formed by friction stir welding and on the grain size in the weld core is studied. It is shown that the design of tool and, especially, the parameters of a screw groove exert a great effect on the grain size in the weld core.

Gas tungsten arc welding of aluminum alloys 6XXX. Welding procedure specification

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wodtke, C.H.; Frizzell, D.R.; Plunkett, W.A.

1985-08-01

Procedure WPS-1003 is qualified under Section IX of the ASME Boiler and Pressure Vessel Code for gas tungsten arc welding of aluminum alloys 6061 and 6063 (P-23), in thickness range 0.035 to 0.516 in.; filler metal is ER4043 (F-23) or ER5356 (F-22); shielding gas is argon.

Laser beam interactions with vapor plumes during Nd:YAG laser welding on aluminum

NASA Astrophysics Data System (ADS)

Peebles, H. C.; Russo, A. J.; Hadley, G. R.; Akau, R. L.

Welds produced on pure aluminum targets using pulsed Nd:YAG lasers can be accurately described using a relatively simple conduction mode heat transfer model provided that the fraction of laser energy absorbed is known and the amount of metal vaporized is smalled however at laser fluences commonly used in many production welding schedules significant aluminum vaporization does occur. The possible mechanisms have been identified which could result in laser beam attenuation by the vapor plume.

Continuous internal channels formed in aluminum fusion welds

NASA Technical Reports Server (NTRS)

Gault, J.; Sabo, W.

1967-01-01

Process produces continuous internal channel systems on a repeatable basis in 2014-T6 aluminum. Standard machining forms the initial channel, which is filled with tungsten carbide powder. TIG machine fusion welding completes formation of the channel. Chem-mill techniques enlarge it to the desired size.

Influence of Solute Content and Solidification Parameters on Grain Refinement of Aluminum Weld Metal

NASA Astrophysics Data System (ADS)

Schempp, Philipp; Cross, Carl Edward; Pittner, Andreas; Rethmeier, Michael

2013-07-01

Grain refinement provides an important possibility to enhance the mechanical properties ( e.g., strength and ductility) and the weldability (susceptibility to solidification cracking) of aluminum weld metal. In the current study, a filler metal consisting of aluminum base metal and different amounts of commercial grain refiner Al Ti5B1 was produced. The filler metal was then deposited in the base metal and fused in a GTA welding process. Additions of titanium and boron reduced the weld metal mean grain size considerably and resulted in a transition from columnar to equiaxed grain shape ( CET). In commercial pure aluminum (Alloy 1050A), the grain-refining efficiency was higher than that in the Al alloys 6082 and 5083. Different welding and solidification parameters influenced the grain size response only slightly. Furthermore, the observed grain-size reduction was analyzed by means of the undercooling parameter P and the growth restriction parameter Q, which revealed the influence of solute elements and nucleant particles on grain size.

Mechanical Characteristics of Welded Joints of Aluminum Alloy 6061 T6 Formed by Arc and Friction Stir Welding

NASA Astrophysics Data System (ADS)

Astarita, A.; Squillace, A.; Nele, L.

2016-01-01

Butt welds formed by arc welding in inert gas with nonconsumable electrode (tungsten inert gas (TIG) welding) and by friction stir welding (FSW) from aluminum alloy AA6061 T6 are studied. Comparative analysis of the structures and mechanical properties of the welded joints is performed using the results of optical and electron microscopy, tensile tests, tests for residual bending ductility, and measurements of microhardness. The changes in the microstructure in different zones and the degrees of degradation of the mechanical properties after the welding are determined. It is shown that the size of the tool for the friction stir welding affects the properties of the welds. Quantitative results showing the relation between the microscopic behavior of the alloy and the welding-induced changes in the microstructure are obtained. Friction stir welding is shown to provide higher properties of the welds.

Effect of Interfacial Reaction on the Mechanical Performance of Steel to Aluminum Dissimilar Ultrasonic Spot Welds

NASA Astrophysics Data System (ADS)

Xu, Lei; Wang, Li; Chen, Ying-Chun; Robson, Joe D.; Prangnell, Philip B.

2016-01-01

The early stages of formation of intermetallic compounds (IMC) have been investigated in dissimilar aluminum to steel welds, manufactured by high power (2.5 kW) ultrasonic spot welding (USW). To better understand the influence of alloy composition, welds were produced between a low-carbon steel (DC04) and two different aluminum alloys (6111 and 7055). The joint strengths were measured in lap shear tests and the formation and growth behavior of IMCs at the weld interface were characterized by electron microscopy, for welding times from 0.2 to 2.4 seconds. With the material combinations studied, the η (Fe2Al5) intermetallic phase was found to form first, very rapidly in the initial stage of welding, with a discontinuous island morphology. Continuous layers of η and then θ (FeAl3) phase were subsequently seen to develop on extending the welding time to greater than 0.7 second. The IMC layer formed in the DC04-AA7055 combination grew thicker than for the DC04-AA6111 welds, despite both weld sets having near identical thermal histories. Zinc was also found to be dissolved in the IMC phases when welding with the AA7055 alloy. After post-weld aging of the aluminum alloy, fracture in the lap shear tests always occurred along the joint interface; however, the DC04-AA6111 welds had higher fracture energy than the DC04-AA7055 combination.

Study of 2219 aluminum alloy using direct current A-TIG welding

NASA Astrophysics Data System (ADS)

Li, Hui; Zou, Jiasheng

2017-07-01

Direct current A-TIG (DCEN A-TIG) welding using special active agent had eliminated the pores and the oxidation of 2219 high-strength aluminum alloy in welding. Addition of AlF3-25% LiF active agent to DCEN A-TIG welding and arc morphology showed a trailing phenomenon. However, the change in arc morphology was not remarkable when AlF3-75% LiF active agent was added. Addition of AlF3-75% LiF active agent can refine the grain size of DCEN A-TIG joint. The mechanical properties of the weld were optimal at 10% AlF3-75% LiF active agent. Compared with AC TIG and AC A-TIG welding, DCEN A-TIG welding yielded better results for 2219 Al alloy.

Comparison on welding mode characteristics of arc heat source for heat input control in hybrid welding of aluminum alloy

NASA Astrophysics Data System (ADS)

Song, Moo-Keun; Kim, Jong-Do; Oh, Jae-Hwan

2015-03-01

Presently in shipbuilding, transportation and aerospace industries, the potential to apply welding using laser and laser-arc hybrid heat sources is widely under research. This study has the purpose of comparing the weldability depending on the arc mode by varying the welding modes of arc heat sources in applying laser-arc hybrid welding to aluminum alloy and of implementing efficient hybrid welding while controlling heat input. In the experimental study, we found that hybrid welding using CMT mode produced deeper penetration and sounder bead surface than those characteristics produced during only laser welding, with less heat input compared to that required in pulsed arc mode.

Effect of Mg and Cu on mechanical properties of high-strength welded joints of aluminum alloys obtained by laser welding

NASA Astrophysics Data System (ADS)

Annin, B. D.; Fomin, V. M.; Karpov, E. V.; Malikov, A. G.; Orishich, A. M.

2017-09-01

Results of experimental investigations of welded joints of high-strength aluminum-lithium alloys of the Al-Cu-Li and Al-Mg-Li systems are reported. The welded joints are obtained by means of laser welding and are subjected to various types of processing for obtaining high-strength welded joints. A microstructural analysis is performed. The phase composition and mechanical properties of the welded joints before and after heat treatment are studied. It is found that combined heat treatment of the welded joint (annealing, quenching, and artificial ageing) increases the joint strength, but appreciably decreases the alloy strength outside the region thermally affected by the welding process.

Acoustic Emission Weld Monitoring in the 2195 Aluminum-Lithium Alloy

NASA Technical Reports Server (NTRS)

Walker, James L.

2005-01-01

Due to its low density, the 2195 aluminum-lithium alloy was developed as a replacement for alloy 2219 in the Space Shuttle External Tank (ET). The external tank is the single largest component of the space shuttle system. It is 154 feet long and 27.6 feet in diameter, and serves as the structural backbone for the shuttle during launch, absorbing most of the 7 million plus pounds of thrust produced. The almost 4% decrease in density between the two materials provides an extra 7500 pounds of payload capacity necessary to put the International Space Station components into orbit. The ET is an all-welded structure; hence, the requirement is for up to five rewelds without hot cracking. Unfortunately, hot cracking during re-welding or repair operations was occurring and had to be dealt with before the new super lightweight tank could be used. Weld metal porosity formation was also of concern because it leads to hot cracking during weld repairs. Accordingly, acoustic emission (AE) nondestructive testing was employed to monitor the formation of porosity and hot cracks in order to select the best filler metal and optimize the weld schedule. The purpose of this work is to determine the feasibility of detecting hot cracking in welded aluminum-lithium (Al-Li) structures through the analysis of acoustic emission data. By acoustically characterizing the effects of reheating during a repair operation, the potential for hidden flaws coalescing and becoming "unstable" as the panel is repaired could be reduced. Identification of regions where microcrack growth is likely to occur and the location of active flaw growth in the repair weld will provide the welder with direct feedback as to the current weld quality enabling adjustments to the repair process be made in the field. An acoustic emission analysis of the source mechanisms present during welding has been conducted with the goals of locating regions in the weld line that are susceptible to damage from a repair operation

A Micro-Electrochemical Study of Friction Stir Welded Aluminum 6061-T6

NASA Technical Reports Server (NTRS)

Hintze, Paul E.; Calle, Luz M.

2005-01-01

The corrosion behavior of friction stir welded Aluminum alloy 606 1-T6 was studied using a micro-electrochemical cell. The micro-electrochemical cell has a measurement area of about 0.25 square mm which allows for measurement of corrosion properties at a very small scale. The corrosion and breakdown potentials were measured at many points inside and outside the weld along lines perpendicular to the weld. The breakdown potential is approximately equal inside and outside the weld; however, it is lower in the narrow border between the weld and base material. The results of electrochemical measurements were correlated to micro-structural analysis. The corrosion behavior of the friction stir welded samples was compared to tungsten inert gas (TIG) welded samples of the same material.

Hazard of ultraviolet radiation emitted in gas tungsten arc welding of aluminum alloys.

PubMed

Nakashima, Hitoshi; Utsunomiya, Akihiro; Fujii, Nobuyuki; Okuno, Tsutomu

2016-01-01

Ultraviolet radiation (UVR) emitted during arc welding frequently causes keratoconjunctivitis and erythema. The extent of the hazard of UVR varies depending on the welding method and conditions. Therefore, it is important to identify the levels of UVR that are present under various conditions. In this study, we experimentally evaluated the hazard of UVR emitted in gas tungsten arc welding (GTAW) of aluminum alloys. The degree of hazard of UVR is measured by the effective irradiance defined in the American Conference of Governmental Industrial Hygienists guidelines. The effective irradiances measured in this study are in the range 0.10-0.91 mW/cm(2) at a distance of 500 mm from the welding arc. The maximum allowable exposure times corresponding to these levels are only 3.3-33 s/day. This demonstrates that unprotected exposure to UVR emitted by GTAW of aluminum alloys is quite hazardous in practice. In addition, we found the following properties of the hazard of UVR. (1) It is more hazardous at higher welding currents than at lower welding currents. (2) It is more hazardous when magnesium is included in the welding materials than when it is not. (3) The hazard depends on the direction of emission from the arc.

Hazard of ultraviolet radiation emitted in gas tungsten arc welding of aluminum alloys

PubMed Central

NAKASHIMA, Hitoshi; UTSUNOMIYA, Akihiro; FUJII, Nobuyuki; OKUNO, Tsutomu

2015-01-01

Ultraviolet radiation (UVR) emitted during arc welding frequently causes keratoconjunctivitis and erythema. The extent of the hazard of UVR varies depending on the welding method and conditions. Therefore, it is important to identify the levels of UVR that are present under various conditions. In this study, we experimentally evaluated the hazard of UVR emitted in gas tungsten arc welding (GTAW) of aluminum alloys. The degree of hazard of UVR is measured by the effective irradiance defined in the American Conference of Governmental Industrial Hygienists guidelines. The effective irradiances measured in this study are in the range 0.10–0.91 mW/cm2 at a distance of 500 mm from the welding arc. The maximum allowable exposure times corresponding to these levels are only 3.3–33 s/day. This demonstrates that unprotected exposure to UVR emitted by GTAW of aluminum alloys is quite hazardous in practice. In addition, we found the following properties of the hazard of UVR. (1) It is more hazardous at higher welding currents than at lower welding currents. (2) It is more hazardous when magnesium is included in the welding materials than when it is not. (3) The hazard depends on the direction of emission from the arc. PMID:26632121

Change of Hot Cracking Susceptibility in Welding of High Strength Aluminum Alloy AA 7075

NASA Astrophysics Data System (ADS)

Holzer, M.; Hofmann, K.; Mann, V.; Hugger, F.; Roth, S.; Schmidt, M.

High strength aluminum alloys are known as hard to weld alloys due to their high hot crack susceptibility. However, they have high potential for applications in light weight constructions of automotive industry and therefore it is needed to increase weldability. One major issue is the high hot cracking susceptibility. Vaporization during laser beam welding leads to a change of concentration of the volatile elements magnesium and zinc. Hence, solidification range of the weld and therefore hot cracking susceptibility changes. Additionally, different welding velocities lead to changed solidification conditions with certain influence on hot cracking. This paper discusses the influence of energy per unit length during laser beam welding of AA 7075 on the change of element concentration in the weld seam and the resulting influence on hot cracking susceptibility. Therefore EDS-measurements of weld seams generated with different velocities are performed to determine the change of element concentration. These quantitative data is used to numerically calculate the solidification range in order to evaluate its influence on the hot cracking susceptibility. Besides that, relative hot crack length and mechanical properties are measured. The results increase knowledge about welding of high strength aluminum alloy AA 7075 and hence support further developing of the welding process.

Technique for in-place welding of aluminum backed up by a combustible material

NASA Technical Reports Server (NTRS)

Spagnuolo, A. C.

1971-01-01

Welding external aluminum jacket, tightly wrapped around inner layer of wood composition fiberboard, in oxygen free environment prevents combustion and subsequent damage to underlying fiberboard. Technique also applies to metal cutting in similar assemblies without disassembly to remove combustible materials from welding heat proximity.

Damage Tolerance Assessment of Friction Pull Plug Welds in an Aluminum Alloy

NASA Technical Reports Server (NTRS)

McGill, Preston; Burkholder, Jonathan

2012-01-01

Friction stir welding is a solid state welding process used in the fabrication of cryogenic propellant tanks. Self-reacting friction stir welding is one variation of the friction stir weld process being developed for manufacturing tanks. Friction pull plug welding is used to seal the exit hole that remains in a circumferential self-reacting friction stir weld. A friction plug weld placed in a self-reacting friction stir weld results in a non-homogenous weld joint where the initial weld, plug weld, their respective heat affected zones and the base metal all interact. The welded joint is a composite plastically deformed material system with a complex residual stress field. In order to address damage tolerance concerns associated with friction plug welds in safety critical structures, such as propellant tanks, nondestructive inspection and proof testing may be required to screen hardware for mission critical defects. The efficacy of the nondestructive evaluation or the proof test is based on an assessment of the critical flaw size. Test data relating residual strength capability to flaw size in an aluminum alloy friction plug weld will be presented.

Numerical Simulation and Experimental Validation of MIG Welding of T-Joints of Thin Aluminum Plates for Top Class Vehicles

NASA Astrophysics Data System (ADS)

Bonazzi, Enrico; Colombini, Elena; Panari, Davide; Vergnano, Alberto; Leali, Francesco; Veronesi, Paolo

2017-01-01

The integration of experiments with numerical simulations can efficiently support a quick evaluation of the welded joint. In this work, the MIG welding operation on aluminum T-joint thin plate has been studied by the integration of both simulation and experiments. The aim of the paper is to enlarge the global database, to promote the use of thin aluminum sheets in automotive body industries and to provide new data. Since the welding of aluminum thin plates is difficult to control due to high speed of the heat source and high heat flows during heating and cooling, a simulation model could be considered an effective design tool to predict the real phenomena. This integrated approach enables new evaluation possibilities on MIG-welded thin aluminum T-joints, as correspondence between the extension of the microstructural zones and the simulation parameters, material hardness, transient 3D temperature distribution on the surface and inside the material, stresses, strains, and deformations. The results of the mechanical simulations are comparable with the experimental measurements along the welding path, especially considering the variability of the process. The results could well predict the welding-induced distortion, which together with local heating during welding must be anticipated and subsequently minimized and counterbalance.

Effects of high frequency current in welding aluminum alloy 6061

NASA Technical Reports Server (NTRS)

Fish, R. E.

1968-01-01

Uncontrolled high frequency current causes cracking in the heat-affected zone of aluminum alloy 6061 weldments during tungsten inert gas ac welding. Cracking developed when an improperly adjusted superimposed high frequency current was agitating the semimolten metal in the areas of grain boundary.

Microstructure and Mechanical Properties of an Ultrasonic Spot Welded Aluminum Alloy: The Effect of Welding Energy

PubMed Central

Peng, He; Chen, Daolun; Jiang, Xianquan

2017-01-01

The aim of this study is to evaluate the microstructures, tensile lap shear strength, and fatigue resistance of 6022-T43 aluminum alloy joints welded via a solid-state welding technique–ultrasonic spot welding (USW)–at different energy levels. An ultra-fine necklace-like equiaxed grain structure is observed along the weld line due to the occurrence of dynamic crystallization, with smaller grain sizes at lower levels of welding energy. The tensile lap shear strength, failure energy, and critical stress intensity of the welded joints first increase, reach their maximum values, and then decrease with increasing welding energy. The tensile lap shear failure mode changes from interfacial fracture at lower energy levels, to nugget pull-out at intermediate optimal energy levels, and to transverse through-thickness (TTT) crack growth at higher energy levels. The fatigue life is longer for the joints welded at an energy of 1400 J than 2000 J at higher cyclic loading levels. The fatigue failure mode changes from nugget pull-out to TTT crack growth with decreasing cyclic loading for the joints welded at 1400 J, while TTT crack growth mode remains at all cyclic loading levels for the joints welded at 2000 J. Fatigue crack basically initiates from the nugget edge, and propagates with “river-flow” patterns and characteristic fatigue striations. PMID:28772809

Microstructure and Mechanical Properties of an Ultrasonic Spot Welded Aluminum Alloy: The Effect of Welding Energy.

PubMed

Peng, He; Chen, Daolun; Jiang, Xianquan

2017-04-25

The aim of this study is to evaluate the microstructures, tensile lap shear strength, and fatigue resistance of 6022-T43 aluminum alloy joints welded via a solid-state welding technique-ultrasonic spot welding (USW)-at different energy levels. An ultra-fine necklace-like equiaxed grain structure is observed along the weld line due to the occurrence of dynamic crystallization, with smaller grain sizes at lower levels of welding energy. The tensile lap shear strength, failure energy, and critical stress intensity of the welded joints first increase, reach their maximum values, and then decrease with increasing welding energy. The tensile lap shear failure mode changes from interfacial fracture at lower energy levels, to nugget pull-out at intermediate optimal energy levels, and to transverse through-thickness (TTT) crack growth at higher energy levels. The fatigue life is longer for the joints welded at an energy of 1400 J than 2000 J at higher cyclic loading levels. The fatigue failure mode changes from nugget pull-out to TTT crack growth with decreasing cyclic loading for the joints welded at 1400 J, while TTT crack growth mode remains at all cyclic loading levels for the joints welded at 2000 J. Fatigue crack basically initiates from the nugget edge, and propagates with "river-flow" patterns and characteristic fatigue striations.

Investigations on Laser Beam Welding of Different Dissimilar Joints of Steel and Aluminum Alloys for Automotive Lightweight Construction

NASA Astrophysics Data System (ADS)

Seffer, Oliver; Pfeifer, Ronny; Springer, André; Kaierle, Stefan

Due to the enormous potential of weight saving, and the consequential reduction of pollutant emissions, the use of hybrid components made of steel and aluminum alloys is increasing steadily, especially concerning automotive lightweight construction. However, thermal joining of steel and aluminum is still being researched, due to a limited solubility of the binary system of iron and aluminum causing the formation of hard and brittle intermetallic phases, which decrease the strength and the formability of the dissimilar seam. The presented results show the investigation of laser beam welding for joining different dissimilar hybrid components of the steel materials HX220LAD+Z100, 22MnB5+AS150 and 1.4301, as well as the aluminum alloy AA6016-T4 as a lap joint. Among other things, the influences of the energy per unit length, the material grade, the sheet thickness t, the weld type (lap weld, fillet weld) and the arrangement of the base materials in a lap joint (aluminum-sided irradiation, steel-sided irradiation) on the achievable strengths are analyzed. The characterization of the dissimilar joints includes tensile shear tests and metallographic analyses, depending on the energy per unit length.

Resistance spot welding of ultra-fine grained steel sheets produced by constrained groove pressing: Optimization and characterization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Khodabakhshi, F.; Kazeminezhad, M., E-mail: mkazemi@sharif.edu; Kokabi, A.H.

2012-07-15

Constrained groove pressing as a severe plastic deformation method is utilized to produce ultra-fine grained low carbon steel sheets. The ultra-fine grained sheets are joined via resistance spot welding process and the characteristics of spot welds are investigated. Resistance spot welding process is optimized for welding of the sheets with different severe deformations and their results are compared with those of as-received samples. The effects of failure mode and expulsion on the performance of ultra-fine grained sheet spot welds have been investigated in the present paper and the welding current and time of resistance spot welding process according to thesemore » subjects are optimized. Failure mode and failure load obtained in tensile-shear test, microhardness, X-ray diffraction, transmission electron microscope and scanning electron microscope images have been used to describe the performance of spot welds. The region between interfacial to pullout mode transition and expulsion limit is defined as the optimum welding condition. The results show that optimum welding parameters (welding current and welding time) for ultra-fine grained sheets are shifted to lower values with respect to those for as-received specimens. In ultra-fine grained sheets, one new region is formed named recrystallized zone in addition to fusion zone, heat affected zone and base metal. It is shown that microstructures of different zones in ultra-fine grained sheets are finer than those of as-received sheets. - Highlights: Black-Right-Pointing-Pointer Resistance spot welding process is optimized for joining of UFG steel sheets. Black-Right-Pointing-Pointer Optimum welding current and time are decreased with increasing the CGP pass number. Black-Right-Pointing-Pointer Microhardness at BM, HAZ, FZ and recrystallized zone is enhanced due to CGP.« less

Welding IV.

ERIC Educational Resources Information Center

Allegheny County Community Coll., Pittsburgh, PA.

Instructional objectives and performance requirements are outlined in this course guide for Welding IV, a competency-based course in advanced arc welding offered at the Community College of Allegheny County to provide students with proficiency in: (1) single vee groove welding using code specifications established by the American Welding Society…

U-shaped micro-groove fiber based on femtosecond laser processing for humidity sensing

NASA Astrophysics Data System (ADS)

Fu, Gui; Ma, Li-li; Su, Fu-fang; Shi, Meng

2018-05-01

A novel optical fiber sensor with a U-shaped micro-groove structure ablated by femtosecond laser on single-mode fiber for measuring air relative humidity (RH) is reported in this paper. In order to improve the accuracy of sensor, a graphene oxide (GO)/polyvinyl alcohol (PVA) composite film is coated on the surface of micro-groove structure. In the U-shaped micro-groove structure, the remaining core and micro-cavity in the micro-groove make up two major optical propagation paths, forming a Mach-Zehnder interferometer (MZI). The sensor has a good linear response within the RH range of 30%—85%, and the maximum sensitivity can reach 0.638 1 nm/%RH. The effect of temperature on the overall performance of the humidity sensor is also investigated. As a new type of all-fiber device, the sensor shows excellent sensitivity and stability.

Parameter optimization of flux-aided backing-submerged arc welding by using Taguchi method

NASA Astrophysics Data System (ADS)

Pu, Juan; Yu, Shengfu; Li, Yuanyuan

2017-07-01

Flux-aided backing-submerged arc welding has been conducted on D36 steel with thickness of 20 mm. The effects of processing parameters such as welding current, voltage, welding speed and groove angle on welding quality were investigated by Taguchi method. The optimal welding parameters were predicted and the individual importance of each parameter on welding quality was evaluated by examining the signal-to-noise ratio and analysis of variance (ANOVA) results. The importance order of the welding parameters for the welding quality of weld bead was: welding current > welding speed > groove angle > welding voltage. The welding quality of weld bead increased gradually with increasing welding current and welding speed and decreasing groove angle. The optimum values of the welding current, welding speed, groove angle and welding voltage were found to be 1050 A, 27 cm/min, 40∘ and 34 V, respectively.

Microstructure and Mechanical Properties of Three-Layer TIG-Welded 2219 Aluminum Alloys with Dissimilar Heat Treatments

NASA Astrophysics Data System (ADS)

Zhang, Dengkui; Li, Quan; Zhao, Yue; Liu, Xianli; Song, Jianling; Wang, Guoqing; Wu, Aiping

2018-05-01

2219-C10S and 2219-CYS aluminum alloys are 2219 aluminum alloys with different heat treatment processes, and they have been widely used in the aerospace industry. In the present study, 2219-C10S and 2219-CYS aluminum alloys were butt-welded by three-layer tungsten inert gas arc welding (with the welding center of the third layer shifted toward the CYS side), and the microstructure characteristics and mechanical properties of the welded joint were investigated. The lamellar θ' phases, the bulk or rod θ phases, and the coarse rod-shaped or pancake-shaped Al-Cu-Fe-Mn phases coexisted in the two aluminum alloys. The Cu content of the α-Al matrix and the distribution of eutectic structures of different welding layers in the weld zone (WZ) were varied, implying that the segregation degrees of the Cu element were different due to the different welding thermal cycles in different welding layers. The microhardness values of the CYS side were much higher than those of the C10S side in each region on both sides of the joint. The tensile test deformation was concentrated mainly in the regions of WZ and the over aged zone (OAZ), where the microhardness values were relatively low. The main deformation concentrated region was transferred from the CYS side to the C10S side with the increase in the tensile load during the tensile test. The fracture behavior of the tensile test showed that the macroscopic crack initiated near the front weld toe had gone through the crack blunt region, the shear fracture region of the partially melted zone (PMZ), and the shear fracture region of OAZ. Meanwhile, the fracture characteristics gradually evolved from brittle to ductile. The concentrated stress and the dense eutectic structure in the region near the front weld toe of the C10S side contributed to the fracture of the joint. The shift of the welding center of the third layer to the CYS side resulted in two effects: (i) the microhardness values from the middle layer to the top layer in the

Experimental and Numerical Study on the Strength of Aluminum Extrusion Welding.

PubMed

Bingöl, Sedat; Bozacı, Atilla

2015-07-17

The quality of extrusion welding in the extruded hollow shapes is influenced significantly by the pressure and effective stress under which the material is being joined inside the welding chamber. However, extrusion welding was not accounted for in the past by the developers of finite element software packages. In this study, the strength of hollow extrusion profile with seam weld produced at different ram speeds was investigated experimentally and numerically. The experiments were performed on an extruded hollow aluminum profile which was suitable to obtain the tensile tests specimens from its seam weld's region at both parallel to extrusion direction and perpendicular to extrusion direction. A new numerical modeling approach, which was recently proposed in literature, was used for numerical analyses of the study. The simulation results performed at different ram speeds were compared with the experimental results, and a good agreement was obtained.

Effect of Zinc Coatings on Joint Properties and Interfacial Reactions in Aluminum to Steel Ultrasonic Spot Welding

NASA Astrophysics Data System (ADS)

Haddadi, F.; Strong, D.; Prangnell, P. B.

2012-03-01

Dissimilar joining of aluminum to steel sheet in multimaterial automotive structures is an important potential application of ultrasonic spot welding (USW). Here, the weldability of different zinc-coated steels with aluminum is discussed, using a 2.5-kW USW welder. Results show that soft hot-dipped zinc (DX56-Z)-coated steel results in better weld performance than hard (galv-annealed) zinc coatings (DX53-ZF). For Al to hard galv-annealed-coated steel welds, lap shear strengths reached a maximum of ~80% of the strength of an Al-Al joint after a 1.0 s welding time. In comparison, welds between Al6111-T4 and hot dipped soft zinc-coated steel took longer to achieve the same maximum strength, but nearly matched the Al-Al joint properties. The reasons for these different behaviors are discussed in terms of the interfacial reactions between the weld members.

Thermal Impacts in Vibration-assisted Laser Deep Penetration Welding of Aluminum

NASA Astrophysics Data System (ADS)

Radel, T.

Mechanical vibrations affect the nucleation and grain growth conditions during welding. In order to understand the vibration-induced influences on the grain formation conditions in laser beam welding of aluminum the thermal impacts of simultaneously applied vibrations are analyzed in this study. Therefore, laser deep penetration welding at vibration frequencies between 0.5 kHz and 5 kHz is investigated. Besides full penetration, partial penetration experiments were carried out. The results show that the thermal and absorption efficiencies are not significantly affected by the applied excitation. The solidification time increases in case of applied excitation which is rather disadvantageous regarding grain refinement. Thus, mechanical-metallurgical and not thermal-metallurgical effects should be responsible for the change in grain nucleation and grain growth conditions in laser beam welding with simultaneously applied vibrations.

Dissimilar Joining of Stainless Steel and 5083 Aluminum Alloy Sheets by Gas Tungsten Arc Welding-Brazing Process

NASA Astrophysics Data System (ADS)

Cheepu, Muralimohan; Srinivas, B.; Abhishek, Nalluri; Ramachandraiah, T.; Karna, Sivaji; Venkateswarlu, D.; Alapati, Suresh; Che, Woo Seong

2018-03-01

The dissimilar joining using gas tungsten arc welding - brazing of 304 stainless steel to 5083 Al alloy had been conducted with the addition of Al-Cu eutectic filler metal. The interface microstructure formation between filler metal and substrates, and spreading of the filler metal were studied. The interface microstructure between filler metal and aluminum alloy characterized that the formation of pores and elongated grains with the initiation of micro cracks. The spreading of the liquid braze filler on stainless steel side packed the edges and appeared as convex shape, whereas a concave shape has been formed on aluminum side. The major compounds formed at the fusion zone interface were determined by using X-ray diffraction techniques and energy-dispersive X-ray spectroscopy analysis. The micro hardness at the weld interfaces found to be higher than the substrates owing to the presence of Fe2Al5 and CuAl2 intermetallic compounds. The maximum tensile strength of the weld joints was about 95 MPa, and the tensile fracture occurred at heat affected zone on weak material of the aluminum side and/or at stainless steel/weld seam interface along intermetallic layer. The interface formation and its effect on mechanical properties of the welds during gas tungsten arc welding-brazing has been discussed.

The Strength and Characteristics of VPPA Welded 2219-T87 Aluminum Alloy

NASA Technical Reports Server (NTRS)

Jemian, W. A.

1985-01-01

A study of the variable polarity plasma arc (VPPA) welding process and those factors that control the structure and properties of VPPA welded aluminum alloy 2219-T87 was conducted. The importance of joint preparation, alignment of parts and welding process variables are already established. Internal weld defects have been eliminated. However, a variation of properties was found to be due to the size variation of interdendritic particles in the fusion zone. These particles contribute to the void formation process, which controls the ultimate tensile strength of the welded alloy. A variation of 150 microns in particle size correlated with a 10 ksi variation of ultimate tensile strength. It was found that all fracture surfaces were of the dimple rupture type, with fracture initiating within the fusion zone.

Effect of different filler wires on weld formation for fiber laser welding 6A02 Aluminum alloy

NASA Astrophysics Data System (ADS)

Xu, F.; Chen, L.; Lu, W.; He, E. G.

2017-12-01

6A02 aluminum alloy was welded by fibre laser welding with two different filler wires (ER4043 and ER5356). The weld apperance, microstructure and mechanical properties were analysed. The results show the welding course with ER4043 is more stable than that with ER5356, and the welding spatters of the former are smaller than that of the latter. The microsturtrue of the weld zone, including columnar-grains near the fusion zone and mixed microstructures (columnar grains and equiaxed grains) in the weld center zone, is finer with ER5356 than that with ER4043. So the average microhardness value of the former is higher than the latter. A great number of low melting point eutectic phases disperse in grains boundary. Due to the eutectic phases distributing more in two zones (overheat zone near the fusion zone and the weld center zone) than other zones, the welded joints have these two low hardness and weak strength zones. The ultimate strength and the elongations after fracture of the welded joints with ER4043 are lower than that with ER5356 slihgtly. However, the former are improved obviously and higher than the latter after heat treatment. The tensile properties of all joints can reach to the base material level. And the tensile fractures always occur near the fusion zone.

Modeling, simulation and control of pulsed DE-GMA welding process for joining of aluminum to steel

NASA Astrophysics Data System (ADS)

Zhang, Gang; Shi, Yu; Li, Jie; Huang, Jiankang; Fan, Ding

2014-09-01

Joining of aluminum to steel has attracted significant attention from the welding research community, automotive and rail transportation industries. Many current welding methods have been developed and applied, however, they can not precisely control the heat input to work-piece, they are high costs, low efficiency and consist lots of complex welding devices, and the generated intermetallic compound layer in weld bead interface is thicker. A novel pulsed double electrode gas metal arc welding(Pulsed DE-GMAW) method is developed. To achieve a stable welding process for joining of aluminum to steel, a mathematical model of coupled arc is established, and a new control scheme that uses the average feedback arc voltage of main loop to adjust the wire feed speed to control coupled arc length is proposed and developed. Then, the impulse control simulation of coupled arc length, wire feed speed and wire extension is conducted to demonstrate the mathematical model and predict the stability of welding process by changing the distance of contact tip to work-piece(CTWD). To prove the proposed PSO based PID control scheme's feasibility, the rapid prototyping experimental system is setup and the bead-on-plate control experiments are conducted to join aluminum to steel. The impulse control simulation shows that the established model can accurately represent the variation of coupled arc length, wire feed speed and the average main arc voltage when the welding process is disturbed, and the developed controller has a faster response and adjustment, only runs about 0.1 s. The captured electric signals show the main arc voltage gradually closes to the supposed arc voltage by adjusting the wire feed speed in 0.8 s. The obtained typical current waveform demonstrates that the main current can be reduced by controlling the bypass current under maintaining a relative large total current. The control experiment proves the accuracy of proposed model and feasibility of new control scheme

High Rotation Speed Friction Stir Welding for 2014 Aluminum Alloy Thin Sheets

NASA Astrophysics Data System (ADS)

Chen, Shujin; Zhou, Yang; Xue, Junrong; Ni, Ruiyang; Guo, Yue; Dong, Jianghui

2017-03-01

In this study, 2014 aluminum alloy sheets with 1 mm thickness are welded successfully by friction stir welding (FSW) robot under the condition of high rotation speed. When the high rotation speed of 10,000-16,500 rpm is applied, the lower axial pressure (less than 200 N) is obtained, which reduces stiffness requirements for equipment. Welding deformation is inevitable because high rotation speed can easily result in rapid heating rate and uneven heat input. The welding distortion caused by two cooling methods is measured, respectively, by laser range finder. The experimental results show that the welding distortion is smaller under the condition of water cooling. When the rotation speed is up to 15,000 rpm and welding speed 50-170 mm/min, the whole welding process is controllable. Under the higher rotation speed condition, the welding defects disappear gradually and more stable mechanical properties can be obtained up to 75% of base metal (ω = 16,000 rpm, ν = 110 mm/min). The results of different welding parameters demonstrate that the high rotation speed can increase material mixing and reduce the axial force (z force), and it can benefit lightweight sheet welding by using FSW robot.

Method for welding beryllium

DOEpatents

Dixon, Raymond D.; Smith, Frank M.; O'Leary, Richard F.

1997-01-01

A method is provided for joining beryllium pieces which comprises: depositing aluminum alloy on at least one beryllium surface; contacting that beryllium surface with at least one other beryllium surface; and welding the aluminum alloy coated beryllium surfaces together. The aluminum alloy may be deposited on the beryllium using gas metal arc welding. The aluminum alloy coated beryllium surfaces may be subjected to elevated temperatures and pressures to reduce porosity before welding the pieces together. The aluminum alloy coated beryllium surfaces may be machined into a desired welding joint configuration before welding. The beryllium may be an alloy of beryllium or a beryllium compound. The aluminum alloy may comprise aluminum and silicon.

Method for welding beryllium

DOEpatents

Dixon, R.D.; Smith, F.M.; O`Leary, R.F.

1997-04-01

A method is provided for joining beryllium pieces which comprises: depositing aluminum alloy on at least one beryllium surface; contacting that beryllium surface with at least one other beryllium surface; and welding the aluminum alloy coated beryllium surfaces together. The aluminum alloy may be deposited on the beryllium using gas metal arc welding. The aluminum alloy coated beryllium surfaces may be subjected to elevated temperatures and pressures to reduce porosity before welding the pieces together. The aluminum alloy coated beryllium surfaces may be machined into a desired welding joint configuration before welding. The beryllium may be an alloy of beryllium or a beryllium compound. The aluminum alloy may comprise aluminum and silicon. 9 figs.

Effect of zirconium addition on welding of aluminum grain refined by titanium plus boron

NASA Astrophysics Data System (ADS)

Zaid, A. I. O.

2014-06-01

Aluminum oxidizes freely in ordinary atmosphere which makes its welding difficult and weak, particularly it solidifies in columnar structure with large grains. Therefore, it is anticipated that the effect of addition of some grain refiners to its melt before solidification is worth while investigating as it may enhance its weldabilty and improve its mechanical strength. In this paper, the effect of addition of zirconium at a weight of 0.1% (which corresponds to the peretictic limit on the aluminum-zirconium base phase diagram) to commercially pure aluminum, grain refined by Ti+B on its weldability, using gas tungsten arc welding, GTAW, method which was formerly known as TIG. A constant current level of 30 AC Ampere was used because it removes the oxides during the welding process. Metallographic examination of the weldments of the different combinations of Al with Al and Al with its microalloys: in the heat affected zone, HAZ, and away from it was carried out and examined for HAZ width, porosity, cracks and microhardness. It was found that grain refining by Ti+B or Zr resulted in enhancement of the weldment.

The effect of impurity gasses on variable polarity plasma arc welded 2219 aluminum

NASA Technical Reports Server (NTRS)

Mcclure, John C.; Torres, Martin R.; Gurevitch, Alan C.; Newman, Robert A.

1989-01-01

Variable polarity plasma arc (VPPA) welding has been used with considerable success by NASA for the welds on the Space Shuttle External Tank as well as by others concerned with high quality welded structures. The effects of gaseous contaminants on the appearance of VPPA welds on 2219 aluminum are examined so that a welder can recognize that such contamination is present and take corrective measures. There are many possible sources of such contamination including, contaminated gas bottles, leaks in the gas plumbing, inadequate shield gas flow, condensed moisture in the gas lines or torch body, or excessive contaminants on the workpiece. The gasses chosen for study in the program were nitrogen, oxygen, methane, and hydrogen. Welds were made in a carefully controlled environment and comparisons were made between welds with various levels of these contaminants and welds made with research purity (99.9999 percent) gasses. Photographs of the weld front and backside as well as polished and etched cross sections are presented.

49 CFR 178.68 - Specification 4E welded aluminum cylinders.

Code of Federal Regulations, 2011 CFR

2011-10-01

...) Where: S = wall stress in psi; P = minimum test pressure prescribed for water jacket test; D = outside... and service pressure. A DOT 4E cylinder is a welded aluminum cylinder with a water capacity (nominal... stress at twice service pressure may not exceed the lesser value of either of the following: (i) 20,000...

Effects of Pulse Parameters on Weld Microstructure and Mechanical Properties of Extra Pulse Current Aided Laser Welded 2219 Aluminum Alloy Joints.

PubMed

Zhang, Xinge; Li, Liqun; Chen, Yanbin; Yang, Zhaojun; Chen, Yanli; Guo, Xinjian

2017-09-15

In order to expand the application range of laser welding and improve weld quality, an extra pulse current was used to aid laser-welded 2219 aluminum alloy, and the effects of pulse current parameters on the weld microstructure and mechanical properties were investigated. The effect mechanisms of the pulse current interactions with the weld pool were evaluated. The results indicated that the coarse dendritic structure in the weld zone changed to a fine equiaxed structure using an extra pulse current, and the pulse parameters, including medium peak current, relatively high pulse frequency, and low pulse duty ratio benefited to improving the weld structure. The effect mechanisms of the pulse current were mainly ascribed to the magnetic pinch effect, thermal effect, and electromigration effect caused by the pulse current. The effect of the pulse parameters on the mechanical properties of welded joints were consistent with that of the weld microstructure. The tensile strength and elongation of the optimal pulse current-aided laser-welded joint increased by 16.4% and 105%, respectively, compared with autogenous laser welding.

Effects of Pulse Parameters on Weld Microstructure and Mechanical Properties of Extra Pulse Current Aided Laser Welded 2219 Aluminum Alloy Joints

PubMed Central

Zhang, Xinge; Li, Liqun; Chen, Yanbin; Yang, Zhaojun; Chen, Yanli; Guo, Xinjian

2017-01-01

In order to expand the application range of laser welding and improve weld quality, an extra pulse current was used to aid laser-welded 2219 aluminum alloy, and the effects of pulse current parameters on the weld microstructure and mechanical properties were investigated. The effect mechanisms of the pulse current interactions with the weld pool were evaluated. The results indicated that the coarse dendritic structure in the weld zone changed to a fine equiaxed structure using an extra pulse current, and the pulse parameters, including medium peak current, relatively high pulse frequency, and low pulse duty ratio benefited to improving the weld structure. The effect mechanisms of the pulse current were mainly ascribed to the magnetic pinch effect, thermal effect, and electromigration effect caused by the pulse current. The effect of the pulse parameters on the mechanical properties of welded joints were consistent with that of the weld microstructure. The tensile strength and elongation of the optimal pulse current-aided laser-welded joint increased by 16.4% and 105%, respectively, compared with autogenous laser welding. PMID:28914825

Effect of water-cooling treatment times on properties of friction stir welded joints of 7N01-T4 aluminum alloy

NASA Astrophysics Data System (ADS)

Zhang, T. H.; Wang, Y.; Fang, X. F.; Liang, P.; Zhao, Y.; Li, Y. H.; Liu, X. M.

2018-02-01

Due to the deformation caused by residual stress in the welding process, welded components need treatment to reduce welding distortion. In this paper, several different times of flame-heating and water-cooling treatment were subjected to the friction stir welding joints of 15mm thick 7N01P-T4 aluminum alloy sheets to study the microstructure variation of friction stir welding joints of 7N01P-T4 aluminum alloy, and to analyze the effect on micro-hardness, tensile and fracture mechanical properties. This investigation will be helpful to optimize treatment methods and provide instruction on industrial production.

Heat Treatment of Friction-Stir-Welded 7050 Aluminum Plates

NASA Technical Reports Server (NTRS)

Petter, George E.; Figert, John D.; Rybicki, Daniel J.; Burns, Timothy

2006-01-01

A method of heat treatment has been developed to reverse some of the deleterious effects of friction stir welding of plates of aluminum alloy 7050. This alloy is considered unweldable by arc and high-energy-density beam fusion welding processes. The alloy can be friction stir welded, but as-welded workpieces exhibit low ductility, low tensile and yield strengths, and low resistance to stress corrosion cracking. Heat treatment according to the present method increases tensile and yield strengths, and minimizes or eliminates stress corrosion cracking. It also increases ductility. This method of heat treatment is a superior alternative to a specification-required heat treatment that caused the formation of large columnar grains, which are undesired. Workpieces subjected to the prior heat treatment exhibited elongations <2 percent, and standard three-point bend specimens shattered. The development of the present heat treatment method was guided partly by the principles that (1) by minimizing grain sizes and relieving deformation stresses, one can minimize or eliminate stress corrosion cracking and (2) the key to maximizing strength and eliminating residual stresses is to perform post-weld solution heating for as long a time as possible while incurring little or no development of large columnar grains in friction stir weld nuggets. It is necessary to perform some of the solution heat treatment (to soften the alloy and improve machine welding parameters) before welding. The following is an example of thickness- dependent pre- and post-weld heat treatments according to the present method: For plates 0.270 in. (approx.6.86 mm) thick milled from plates 4.5 in. (114.3 mm) thick, perform pre-weld solution heating at 890 F (477 C) for 1 hour, then cool in air. After friction stir welding, perform solution heating for 10 minutes, quench, hold at room temperature for 96 hours, then age at 250 F (121 C) for 5 hours followed by 325 F (163 C) for 27 hours.

Effect of adding powder on joint properties of laser penetration welding for dual phase steel and aluminum alloy

NASA Astrophysics Data System (ADS)

Zhou, D. W.; Liu, J. S.; Lu, Y. Z.; Xu, S. H.

2017-09-01

The experiments of laser penetration welding for dual phase steel and aluminum alloy were carried out, and the effect of adding Mn or Si powder on mechanical properties and microstructure of the weld was investigated. Some defects, such as spatter, inclusion, cracks and softening in heat affected zone (HAZ), can be avoided in welding joints, and the increased penetration depth is obtained by adding Mn or Si powder. The average tensile-shear strength of Si-added joint is 3.84% higher than that of Mn-added joint, and the strength of both joints exceeds that of no-added joint. In the case of adding Mn powder, small amount of liquid Al is mixed into steel molten pool, and the Al content increases in both sides of the weld, which leads to the increased weld width in aluminum molten pool. Thus, transverse area increases in jointing steel to aluminum, which is significant for the improved tensile-shear strength of joints. As far as adding Si powder is concerned, it is not the case, the enhancement of the joint properties benefits from improvement of metallurgical reaction.

Improving Mechanical Properties of PVPPA Welded Joints of 7075 Aluminum Alloy by PWHT

PubMed Central

Li, Guowei; Chen, Furong; Han, Yongquan; Liang, Yahong

2018-01-01

In this study, 7075 aluminum alloy with a thickness of 10 mm was successfully welded with no obvious defects by pulsed variable polarity plasma arc (PVPPA) welding. The mechanical properties of PVPPA welded joints have been researched by post weld heat treatment (PWHT). The results indicate that the heat treatment strongly affects the mechanical properties of the welded joints. The tensile strength and the microhardness of the welded joints gradually improved with the increase of the solution temperature. With the increase of the solution time, the tensile strength, and microhardness first dramatically increased and then decreased slightly. The best tensile strength of 537.5 MPa and the microhardness of 143.7 HV were obtained after 490 °C × 80 min + 120 °C × 24 h, and the strength was nearly 91.2% of that of the parent metal, and increased about 35% compared with as-welded. The improvement of strength and microhardness was mainly due to the precipitation of η′ phase. PMID:29510551

Microstructure and Mechanical Performance of Friction Stir Spot-Welded Aluminum-5754 Sheets

NASA Astrophysics Data System (ADS)

Pathak, N.; Bandyopadhyay, K.; Sarangi, M.; Panda, Sushanta Kumar

2013-01-01

Friction stir spot welding (FSSW) is a recent trend of joining light-weight sheet metals while fabricating automotive and aerospace body components. For the successful application of this solid-state welding process, it is imperative to have a thorough understanding of the weld microstructure, mechanical performance, and failure mechanism. In the present study, FSSW of aluminum-5754 sheet metal was tried using tools with circular and tapered pin considering different tool rotational speeds, plunge depths, and dwell times. The effects of tool design and process parameters on temperature distribution near the sheet-tool interface, weld microstructure, weld strength, and failure modes were studied. It was found that the peak temperature was higher while welding with a tool having circular pin compared to tapered pin, leading to a bigger dynamic recrystallized stir zone (SZ) with a hook tip bending towards the upper sheet and away from the keyhole. Hence, higher lap shear separation load was observed in the welds made from circular pin compared to those made from tapered pin. Due to influence of size and hardness of SZ on crack propagation, three different failure modes of weld nugget were observed through optical cross-sectional micrograph and SEM fractographs.

Influence of Aluminum Content on Grain Refinement and Strength of AZ31 Magnesium GTA Weld Metal

DOE Office of Scientific and Technical Information (OSTI.GOV)

Babu, N. Kishore; Cross, Carl E.

2012-06-28

The goal is to characterize the effect of Al content on AZ31 weld metal, the grain size and strength, and examine role of Al on grain refinement. The approach is to systematically vary the aluminum content of AZ31 weld metal, Measure average grain size in weld metal, and Measure cross-weld tensile properties and hardness. Conclusions are that: (1) increased Al content in AZ31 weld metal results in grain refinement Reason: higher undercooling during solidification; (2) weld metal grain refinement resulted in increased strength & hardness Reason: grain boundary strengthening; and (3) weld metal strength can be raised to wrought basemore » metal levels.« less

Structural Phase Evolution in Ultrasonic-Assisted Friction Stir Welded 2195 Aluminum Alloy Joints

NASA Astrophysics Data System (ADS)

Eliseev, A. A.; Fortuna, S. V.; Kalashnikova, T. A.; Chumaevskii, A. V.; Kolubaev, E. A.

2017-10-01

The authors examined the structural and phase state of fixed joints produced by method of friction stir welding (FSW) and ultrasonic-assisted friction stir welding (UAFSW) from extruded profile of aluminum alloy AA2195. In order to identify the role of ultrasonic application in the course of welding, such characteristics, as volume fraction and average size of secondary particles are compared in the base material and stir zones of FSW and UAFSW joints. By applying the methods of SEM and TEM analysis, researchers established the complex character of phase transitions as a result of ultrasonic application.

Transverse-Weld Tensile Properties of a New Al-4Cu-2Si Alloy as Filler Metal

NASA Astrophysics Data System (ADS)

Sampath, K.

2009-12-01

AA2195, an Al-Cu-Li alloy in the T8P4 age-hardened condition, is a candidate aluminum armor for future combat vehicles, as this material offers higher static strength and ballistic protection than current aluminum armor alloys. However, certification of AA2195 alloy for armor applications requires initial qualification based on the ballistic performance of welded panels in the as-welded condition. Currently, combat vehicle manufacturers primarily use gas metal arc welding (GMAW) process to meet their fabrication needs. Unfortunately, a matching GMAW consumable electrode is currently not commercially available to allow effective joining of AA2195 alloy. This initial effort focused on an innovative, low-cost, low-risk approach to identify an alloy composition suitable for effective joining of AA2195 alloy, and evaluated transverse-weld tensile properties of groove butt joints produced using the identified alloy. Selected commercial off-the-shelf (COTS) aluminum alloy filler wires were twisted to form candidate twisted filler rods. Representative test weldments were produced using AA2195 alloy, candidate twisted filler rods and gas tungsten arc welding (GTAW) process. Selected GTA weldments produced using Al-4wt.%Cu-2wt.%Si alloy as filler metal consistently provided transverse-weld tensile properties in excess of 275 MPa (40 ksi) UTS and 8% El (over 25 mm gage length), thereby showing potential for acceptable ballistic performance of as-welded panels. Further developmental work is required to evaluate in detail GMAW consumable wire electrodes based on the Al-Cu-Si system containing 4.2-5.0 wt.% Cu and 1.6-2.0 wt.% Si.

Experiments and simulation for 6061-T6 aluminum alloy resistance spot welded lap joints

NASA Astrophysics Data System (ADS)

Florea, Radu Stefanel

This comprehensive study is the first to quantify the fatigue performance, failure loads, and microstructure of resistance spot welding (RSW) in 6061-T6 aluminum (Al) alloy according to welding parameters and process sensitivity. The extensive experimental, theoretical and simulated analyses will provide a framework to optimize the welding of lightweight structures for more fuel-efficient automotive and military applications. The research was executed in four primary components. The first section involved using electron back scatter diffraction (EBSD) scanning, tensile testing, laser beam profilometry (LBP) measurements, and optical microscopy(OM) images to experimentally investigate failure loads and deformation of the Al-alloy resistance spot welded joints. Three welding conditions, as well as nugget and microstructure characteristics, were quantified according to predefined process parameters. Quasi-static tensile tests were used to characterize the failure loads in specimens based upon these same process parameters. Profilometer results showed that increasing the applied welding current deepened the weld imprints. The EBSD scans revealed the strong dependency between the grain sizes and orientation function on the process parameters. For the second section, the fatigue behavior of the RSW'ed joints was experimentally investigated. The process optimization included consideration of the forces, currents, and times for both the main weld and post-heating. Load control cyclic tests were conducted on single weld lap-shear joint coupons to characterize the fatigue behavior in spot welded specimens. Results demonstrate that welding parameters do indeed significantly affect the microstructure and fatigue performance for these welds. The third section comprised residual strains of resistance spot welded joints measured in three different directions, denoted as in-plane longitudinal, in-plane transversal, and normal, and captured on the fusion zone, heat affected zone

A Review of Dissimilar Welding Techniques for Magnesium Alloys to Aluminum Alloys.

PubMed

Liu, Liming; Ren, Daxin; Liu, Fei

2014-05-08

Welding of dissimilar magnesium alloys and aluminum alloys is an important issue because of their increasing applications in industries. In this document, the research and progress of a variety of welding techniques for joining dissimilar Mg alloys and Al alloys are reviewed from different perspectives. Welding of dissimilar Mg and Al is challenging due to the formation of brittle intermetallic compound (IMC) such as Mg 17 Al 12 and Mg₂Al₃. In order to increase the joint strength, three main research approaches were used to eliminate or reduce the Mg-Al intermetallic reaction layer. First, solid state welding techniques which have a low welding temperature were used to reduce the IMCs. Second, IMC variety and distribution were controlled to avoid the degradation of the joining strength in fusion welding. Third, techniques which have relatively controllable reaction time and energy were used to eliminate the IMCs. Some important processing parameters and their effects on weld quality are discussed, and the microstructure and metallurgical reaction are described. Mechanical properties of welds such as hardness, tensile, shear and fatigue strength are discussed. The aim of the report is to review the recent progress in the welding of dissimilar Mg and Al to provide a basis for follow-up research.

A Review of Dissimilar Welding Techniques for Magnesium Alloys to Aluminum Alloys

PubMed Central

Liu, Liming; Ren, Daxin; Liu, Fei

2014-01-01

Welding of dissimilar magnesium alloys and aluminum alloys is an important issue because of their increasing applications in industries. In this document, the research and progress of a variety of welding techniques for joining dissimilar Mg alloys and Al alloys are reviewed from different perspectives. Welding of dissimilar Mg and Al is challenging due to the formation of brittle intermetallic compound (IMC) such as Mg17Al12 and Mg2Al3. In order to increase the joint strength, three main research approaches were used to eliminate or reduce the Mg-Al intermetallic reaction layer. First, solid state welding techniques which have a low welding temperature were used to reduce the IMCs. Second, IMC variety and distribution were controlled to avoid the degradation of the joining strength in fusion welding. Third, techniques which have relatively controllable reaction time and energy were used to eliminate the IMCs. Some important processing parameters and their effects on weld quality are discussed, and the microstructure and metallurgical reaction are described. Mechanical properties of welds such as hardness, tensile, shear and fatigue strength are discussed. The aim of the report is to review the recent progress in the welding of dissimilar Mg and Al to provide a basis for follow-up research. PMID:28788646

Gas tungsten arc welding of aluminum alloys 3004, 5052, and 5X54. Welding procedure specification

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wodtke, C.H.; Frizzell, D.R.; Plunkett, W.A.

1985-08-01

Procedure WPS-1002 is qualified under Section IX of the ASME Boiler and Pressure Vessel Code for gas tungsten arc welding of aluminum alloys 3004, 5052, 5154, and 5454 (P-22), in thickness range 0.062 to 0.5 in.; filler metal is ER4043 (F-23) for 3004, and ER5356 (F-22) for other alloys; shielding gas is argon.

FRICTION STIR LAP WELDING OF ALUMINUM - POLYMER USING SCRIBE TECHNOLOGY

DOE Office of Scientific and Technical Information (OSTI.GOV)

Upadhyay, Piyush; Hovanski, Yuri; Fifield, Leonard S.

2015-02-16

Friction Stir Scribe (FSS) technology is a relatively new variant of Friction Stir Welding (FSW) which enables lap joining of dissimilar material with very different melting points and different high temperature flow behaviors. The cutter scribe attached at the tip of FSW tool pin effectively cuts the high melting point material such that a mechanically interlocking feature is created between the dissimilar materials. The geometric shape of this interlocking feature determines the shear strength attained by the lap joint. This work presents first use of scribe technology in joining polymers to aluminum alloy. Details of the several runs of scribemore » welding performed in lap joining of ~3.175mm thick polymers including HDPE, filled and unfilled Nylon 66 to 2mm thick AA5182 are presented. The effect of scribe geometry and length on weld interlocking features is presented along with lap shear strength evaluations.« less

A study of narrow gap laser welding for thick plates using the multi-layer and multi-pass method

NASA Astrophysics Data System (ADS)

Li, Ruoyang; Wang, Tianjiao; Wang, Chunming; Yan, Fei; Shao, Xinyu; Hu, Xiyuan; Li, Jianmin

2014-12-01

This paper details a new method that combines laser autogenous welding, laser wire filling welding and hybrid laser-GMAW welding to weld 30 mm thick plate using a multi-layer, multi-pass process. A “Y” shaped groove was used to create the joint. Research was also performed to optimize the groove size and the processing parameters. Laser autogenous welding is first used to create the backing weld. The lower, narrowest part of the groove is then welded using laser wire filling welding. Finally, the upper part of the groove is welded using laser-GMAW hybrid welding. Additionally, the wire feeding and droplet transfer behaviors are observed by high speed photography. The two main conclusions from this work are: the wire is often biased towards the side walls, resulting in a lack of fusion at the joint and the creation of other defects for larger groove sizes. Additionally, this results in the droplet transfer behavior becoming unstable, leading to a poor weld appearance for smaller groove sizes.

Effect of Post Weld Heat Treatment on Corrosion Behavior of AA2014 Aluminum – Copper Alloy Electron Beam Welds

NASA Astrophysics Data System (ADS)

Venkata Ramana, V. S. N.; Mohammed, Raffi; Madhusudhan Reddy, G.; Srinivasa Rao, K.

2018-03-01

The present work pertains to the study of corrosion behavior of aluminum alloy electron beam welds. The aluminium alloy used in the present study is copper containing AA2014 alloy. Electron Beam Welding (EBW) was used to weld the alloys in annealed (O) condition. Microstructural changes across the welds were recorded and the effect of post weld heat treatment (PWHT) in T4 (Solutionized and naturally aged) condition on pitting corrosion resistance was studied. A software based PAR basic electrochemical system was used for potentio-dynamic polarization tests. From the study it is observed that weld in O condition is prone to more liquation than that of PWHT condition. This may be attributed to re-melting and solidification of excess eutectic present in the O condition of the base metal. It was also observed that slightly higher hardness values are recorded in O condition than that of PWHT condition. The pitting corrosion resistance of the PMZ/HAZ in PWHT condition is better than that of O condition. This is attributed to copper segregation at the grain boundaries of PMZ in O condition.

The feasibility of producing aluminum-lithium structures for cryogenic tankage applications by laser beam welding

NASA Technical Reports Server (NTRS)

Martukanitz, R. P.; Lysher, K. G.

1993-01-01

Aluminum-lithium alloys exhibit high strength, high elastic modulus, and low density as well as excellent cryogenic mechanical properties making them ideal material candidates for cryogenic tanks. NASA has proposed the use of 'built-up' structure for panels fabricated into cryogenic tanks replacing current conventional machining. Superplastically formed stiffeners would be joined to sheet (tank skin) that had been roll formed to the radius of the tank in order to produce panels. Aluminum-lithium alloys of interest for producing the built-up structure include alloy 2095-T6 stiffeners to 2095-T8 sheet and alloy 8090-T6 stiffeners to 2090-T83 sheet. Laser welding, with comparable joint properties, offers the following advantages over conventional welding: higher production rates, minimal degradation within the heat affected zones, and full process automation. This study established process parameters for laser beam welding, mechanical property determinations, metallographic characterization, and fabrication of prototype panels. Tensile tests representing partial penetration of the skin alloys provided joint efficiencies between 65 and 77 percent, depending upon alloy and degree of penetration. Results of tension shear tests of lap welds indicated that the combination of 2095-T6 to 2090-T8 exhibited significantly higher weld shear strength at the interface in comparison to welds of 8090-T6 to 2090-T83. The increased shear strength associated with 2095 is believed to be due to the alloy's ability to precipitation strengthening (naturally age) after welding.

High Temperature Analysis of Aluminum-Lithium 2195 Alloy to Aid in the Design of Improved Welding Techniques

NASA Technical Reports Server (NTRS)

Talia, George E.; Widener, Christian

1996-01-01

Aluminum-lithium alloys have extraordinary properties. The addition of lithium to an aluminum alloy decreases its density, while making large increases in its strength and hardness. The down side is that they are unstable at higher temperatures, and are subsequently difficult to weld or even manufacture. Martin Marietta, though, developed an aluminum-lithium alloy 2195 that was reported to have exceptional properties and good weldability. Thus, it was chosen as the alloy for the space shuttles super light external tank. Unfortunately, welding 2195 has turned out to be much more of a challenge than anticipated. Thus, research has been undergone in order to understand the mechanisms that are causing the welding problems. Gas reactions have been observed to be detrimental to weld strength. Water vapor has often been identified as having a significant role in these reactions. Nitrogen, however, has also been shown to have a direct correlation to porosity. These reactions were suspected as being complex and responsible for the two main problems of welding 2195. One, the initial welds of 2195 are much weaker than the parent metal. Second, each subsequent welding pass increases the size and number of cracks and porosity, yielding significant reductions in strength. Consequently, the objective of this research was to characterize the high-temperature reactions of 2195 in order to understand the mechanisms for crack growth and the formation of porosity in welds. In order to accomplish that goal, an optical hot-stage microscope, HSM, was used to observe those reactions as they occurred. Surface reactions of 2195 were observed in a variety of environments, such as air, vacuum, nitrogen and helium. For comparison, some samples of Al-2219 were also observed. Some of the reacted surfaces were then analyzed on a scanning electron microscope, SEM. Additionally, a gas chromatograph was used to analyze the gaseous products of the high temperature reactions.

Weld bead reinforcement removal: A method of improving the strength and ductility of peaked welds in 2219-T87 aluminum alloy plate

NASA Technical Reports Server (NTRS)

Lovoy, C. V.

1979-01-01

The results of a study to determine the degree to which the ductility and tensile properties of peaked welds could be enhanced by removing the reinforcing bead and fairing the weld nugget into the adjacent parent metal are presented. The study employed 2219-T87 aluminum alloy plate, tungsten inert gas (TIG) welding, and 2319 filler wire. The study concluded that significant improvements in peak weld, ultimate strength, and ductility can be obtained through removal and fairing of the weld reinforcing bead. The specimens so treated and tested in this program exhibited ultimate strength improvements of 2 to 3 percent for peak angles of 5.8 to 10 degrees and 10 to 22 percent for welds with peak angles of 11.7 to 16.9 degrees. It was also determined that removal of the weld bead enhanced the ability of peaked welds to straighten when exposed to cyclic loading at stress levels above the yield strength.

Laser beam joining of optical fibers in silicon V-grooves

NASA Astrophysics Data System (ADS)

Kaufmann, Stefan; Otto, Andreas; Luz, Gerhard

2000-06-01

The increasing use of optical data transmission systems and the development of new optical components require adjustment-insensitive and reliable joining and assembling techniques. The state of the art includes the utilization of silicon submounts with anisotropically etched V-grooves. Several glass fibers are fixed in these V-grooves with adhesive. Adhesive bonds tend towards degradation under the influence of temperature and moisture. For this reason, the alternative joining processes laser beam welding and laser beam soldering are relevant. The goal is a reliable joining of optical fibers in V-grooves without damage to the fibers or the silicon submount. Because of the anomaly of silicon during phase transformation, a positive joining can be realized by laser beam welding. A melt pool is created through the energy of a Nd:YAG-laser pulse. During solidification, the volume of silicon increases and a bump is formed in the center. Experiments have shown that this phenomenon can be used for joining optical fibers in silicon-V-grooves. With suitable parameters the silicon flows half around the fiber during solidification. For each fiber, several welding points are necessary. Another promising joining method is laser bema soldering. In this case, a second silicon sheet with a solder deposit is placed on the fibers which lie in the V-grooves of the metallized silicon submount. The laser heats the upper silicon until the solder metals by heat conduction.

Microstructure of Friction Stir Welded AlSi9Mg Cast with 5083 and 2017A Wrought Aluminum Alloys

NASA Astrophysics Data System (ADS)

Hamilton, C.; Kopyściański, M.; Dymek, S.; Węglowska, A.; Pietras, A.

2018-03-01

Wrought aluminum alloys 5083 and 2017A were each joined with cast aluminum alloy AlSi9Mg through friction stir welding in butt weld configurations. For each material system, the wrought and cast alloy positions, i.e., the advancing side or the retreating side, were exchanged between welding trials. The produced weldments were free from cracks and discontinuities. For each alloy configuration, a well-defined nugget comprised of alternating bands of the welded alloys characterized the microstructure. The degree of mixing, however, strongly depended on which wrought alloy was present and on its position during processing. In all cases, the cast AlSi9Mg alloy dominated the weld center regardless of its position during welding. Electron backscattered diffraction analysis showed that the grain size in both alloys (bands) constituting the nugget was similar and that the majority of grain boundaries exhibited a high angle character (20°-60°). Regardless of the alloy, however, all grains were elongated along the direction of the material plastic flow during welding. A numerical simulation of the joining process visualized the material flow patterns and temperature distribution and helped to rationalize the microstructural observations. The hardness profiles across the weld reflected the microstructure formed during welding and correlated well with the temperature changes predicted by the numerical model. Tensile specimens consistently fractured in the cast alloy near the weld nugget.

Numerical Simulation of Stationary AC Tungsten Inert Gas Welding of Aluminum Plate in Consideration of Oxide Layer Cleaning

NASA Astrophysics Data System (ADS)

Tashiro, Shinichi; Tanaka, Manabu

An unified numerical simulation model of AC TIG welding of the aluminum plate considering energy balance among the electrode, the arc and the base metal and employing an analytical model for calculating cleaning rate of the oxide layer has been developed for investigating heat transport properties and weld pool formation process in AC TIG welding of aluminum plate. As a result of this simulation, it was shown that although the heat flux from the arc onto the base metal increases in EN (Electrode Negative) phase due to the electron condensation, that in EP (Electrode Positive) phase conversely decreases because mainly of cooling caused by the electron emission. Furthermore, the validity of the simulation model was confirmed by comparing to experimental results such as the arc voltage, the area of cleaning zone and the shape of weld pool.

Effect of Rotational Speed on Microstructure and Mechanical Properties of Refill Friction Stir Spot Welded 2024 Al Alloy

NASA Astrophysics Data System (ADS)

Li, Zhengwei; Gao, Shuangsheng; Ji, Shude; Yue, Yumei; Chai, Peng

2016-04-01

Refill friction stir spot welding (RFSSW) was successfully used to weld alclad 2024 aluminum alloy with different thicknesses. Effects of tool rotational speed on the weld formation, microstructure, and mechanical properties of the RFSSW welds were mainly discussed. Results show that keyhole is successfully refilled and welding defects such as flash, annular groove, and material adhesion can be observed. A bright contrast bonding ligament is found embedded in the weld and it is thicker in the center. Defects of hook, void, lack of mixing, and incomplete refilling can be found at the thermo-mechanically affected zone/stir zone (TMAZ/SZ) interface, which can be attributed to weak metallurgical bonding effect. With increasing the tool rotational speed, thickness of the bonding ligament decreases, grains in the SZ coarsen, hardness of the SZ decreases, and lap shear load of the welds decreases. When changing the rotating speed, impact strength shows rather complicated variation trend.

Finite Element Simulation of Temperature and Strain Distribution during Friction Stir Welding of AA2024 Aluminum Alloy

NASA Astrophysics Data System (ADS)

Jain, Rahul; Pal, Surjya Kanta; Singh, Shiv Brat

2017-02-01

Friction Stir Welding (FSW) is a solid state joining process and is handy for welding aluminum alloys. Finite Element Method (FEM) is an important tool to predict state variables of the process but numerical simulation of FSW is highly complex due to non-linear contact interactions between tool and work piece and interdependency of displacement and temperature. In the present work, a three dimensional coupled thermo-mechanical method based on Lagrangian implicit method is proposed to study the thermal history, strain distribution and thermo-mechanical process in butt welding of Aluminum alloy 2024 using DEFORM-3D software. Workpiece is defined as rigid-visco plastic material and sticking condition between tool and work piece is defined. Adaptive re-meshing is used to tackle high mesh distortion. Effect of tool rotational and welding speed on plastic strain is studied and insight is given on asymmetric nature of FSW process. Temperature distribution on the workpiece and tool is predicted and maximum temperature is found in workpiece top surface.

Experimental and numerical analysis on aluminum/steel pipe using magnetic pulse welding

NASA Astrophysics Data System (ADS)

Shim, J. Y.; Kim, I. S.; Lee, K. J.; Kang, B. Y.

2011-12-01

Recently, there has been a trend in the automotive industry to focus on the improvement of lightweight materials, such as aluminum and magnesium because the welding of dissimilar metals causes many welding defects. Magnetic pulse welding (MPW), one of the solid state welding technologies, uses electromagnetic force from current discharged through a working coil which develops a repulsive force between the induced currents flowing parallel and in the opposite direction in the tube to be welded. The objective of this paper is to develop a numerical model for analysis of the interaction between the outer pipe and the working coil using a finite element method (FEM) in the MPW process. Four Maxwell equations are solved using a general electromagnetic mechanics computer program, ANSYS/EMAG code. Experiments were also carried out with a W-MPW60 machine manufactured by WELMATE CO., LTD. with the Al1070 and SM45C for Al pipe and steel bar respectively. The calculated and measured results were compared to verify the proposed model.

Manufacturing of hybrid aluminum copper joints by electromagnetic pulse welding - Identification of quantitative process windows

NASA Astrophysics Data System (ADS)

Psyk, Verena; Scheffler, Christian; Linnemann, Maik; Landgrebe, Dirk

2017-10-01

Compared to conventional joining techniques, electromagnetic pulse welding offers important advantages especially when it comes to dissimilar material connections as e.g. copper aluminum welds. However, due to missing guidelines and tools for process design, the process has not been widely implemented in industrial production, yet. In order to contribute to overcoming this obstacle, a combined numerical and experimental process analysis for electromagnetic pulse welding of Cu-DHP and EN AW-1050 was carried out and the results were consolidated in a quantitative collision parameter based process window.

Experimental Investigation and Optimization of TIG Welding Parameters on Aluminum 6061 Alloy Using Firefly Algorithm

NASA Astrophysics Data System (ADS)

Kumar, Rishi; Mevada, N. Ramesh; Rathore, Santosh; Agarwal, Nitin; Rajput, Vinod; Sinh Barad, AjayPal

2017-08-01

To improve Welding quality of aluminum (Al) plate, the TIG Welding system has been prepared, by which Welding current, Shielding gas flow rate and Current polarity can be controlled during Welding process. In the present work, an attempt has been made to study the effect of Welding current, current polarity, and shielding gas flow rate on the tensile strength of the weld joint. Based on the number of parameters and their levels, the Response Surface Methodology technique has been selected as the Design of Experiment. For understanding the influence of input parameters on Ultimate tensile strength of weldment, ANOVA analysis has been carried out. Also to describe and optimize TIG Welding using a new metaheuristic Nature - inspired algorithm which is called as Firefly algorithm which was developed by Dr. Xin-She Yang at Cambridge University in 2007. A general formulation of firefly algorithm is presented together with an analytical, mathematical modeling to optimize the TIG Welding process by a single equivalent objective function.

Upgrading weld quality of a friction stir welded aluminum alloys AMG6

NASA Astrophysics Data System (ADS)

Chernykh, I. K.; Vasil'ev, E. V.; Matuzko, E. N.; Krivonos, E. V.

2018-01-01

In the course of introduction of FSW technology into the industry there is a keen interest in this process; there are issues such as how does joining take place, what is the structure of the joint, and where there are dangerous zones. The objective of this research is to obtain information about the structure of the joint, what are the temperatures that arise during the joining, what strength is apply to the tool when joining the material, what tensile strength of joint, and where fracture tended to occur. Specimens were produced at different modes of welding at a tool rotation speed of 315 to 625 rpm and tool travel speed of 40 to 125 mm/min. During the experiment, the strength applied to the tool was measured, which reached 800016000 N (Fz) and 400-1400 N (Fx) and the temperature on the surface of the tool, which is in the range 250-400°C. Before the welding process the tool was heated to a temperature in the range of 100-250 degrees, but the tensile strength is not had a tangible impact. The tensile strength is about 80 % of that of the aluminum alloy base metal tensile strength, and fracture tended is occur not at the line of joint but follow the shape of the tool. In the transverse cross section of a FSW material there is a microstructural regions such as weld nugget, thermomechanically affected zone and heat-affected zone with parent material.

Latest MIG, TIG arc-YAG laser hybrid welding systems for various welding products

NASA Astrophysics Data System (ADS)

Ishide, Takashi; Tsubota, Shuho; Watanabe, Masao

2003-03-01

Laser welding is capable of high-efficiency low-strain welding, and so its applications are started to various products. We have also put the high-power YAG laser of up to 10 kW to practical welding use for various products. On the other hand the weakest point of this laser welding is considered to be strict in the welding gap aiming allowance. In order to solve this problem, we have developed hybrid welding of TIG, MIG arc and YAG laser, taking the most advantages of both the laser and arc welding. Since the electrode is coaxial to the optical axis of the YAG laser in this process, it can be applied to welding of various objects. In the coaxial MIG, TIG-YAG welding, in order to make irradiation positions of the YAG laser beams having been guided in a wire or an electrode focused to the same position, the beam transmitted in fibers is separated to form a space between the separated beams, in which the laser is guided. With this method the beam-irradiating area can be brought near or to the arc-generating point. This enables welding of all directions even for the member of a three-dimensional shape. This time we carried out welding for various materials and have made their welding of up to 1 mm or more in welding groove gap possible. We have realized high-speed 1-pass butt welding of 4m/min in welding speed with the laser power of 3 kW for an aluminum alloy plate of approximately 4 mm thick. For a mild steel plate also we have realized butt welding of 1m/min with 5 kW for 6 mm thick. Further, in welding of stainless steel we have shown its welding possibility, by stabilizing the arc with the YAG laser in the welding atmosphere of pure argon, and shown that this welding is effective in high-efficiency welding of various materials. Here we will report the fundamental welding performances and applications to various objects for the coaxial MIG, TIG-YAG welding we have developed.

An Investigation of the Microstructure of an Intermetallic Layer in Welding Aluminum Alloys to Steel by MIG Process

PubMed Central

Nguyen, Quoc Manh; Huang, Shyh-Chour

2015-01-01

Butt joints of A5052 aluminum alloy and SS400 steel, with a new type of chamfered edge, are welded by means of metal inert gas welding and ER4043 Al-Si filler metal. The microhardness and microstructure of the joint are investigated. An intermetallic layer is found on the surface of the welding seam and SS400 steel sheet. The hardness of the intermetallic layer is examined using the Vickers hardness test. The average hardness values at the Intermetallic (IMC) layer zone and without the IMC layer zone were higher than that of the welding wire ER4043. The tensile strength test showed a fracture at the intermetallic layer when the tensile strength is 225.9 MPa. The tensile value test indicated the average of welds was equivalent to the 85% tensile strength of the A5052 aluminum alloy. The thickness of the intermetallic layers is non-uniform at different positions with the ranges from 1.95 to 5 μm. The quality of the butt joint is better if the intermetallic layer is minimized. The Si crystals which appeared at the welding seam, indicating that this element participated actively during the welding process, also contributed to the IMC layer’s formation. PMID:28793708

An Investigation of the Microstructure of an Intermetallic Layer in Welding Aluminum Alloys to Steel by MIG Process.

PubMed

Nguyen, Quoc Manh; Huang, Shyh-Chour

2015-12-02

Butt joints of A5052 aluminum alloy and SS400 steel, with a new type of chamfered edge, are welded by means of metal inert gas welding and ER4043 Al-Si filler metal. The microhardness and microstructure of the joint are investigated. An intermetallic layer is found on the surface of the welding seam and SS400 steel sheet. The hardness of the intermetallic layer is examined using the Vickers hardness test. The average hardness values at the Intermetallic (IMC) layer zone and without the IMC layer zone were higher than that of the welding wire ER4043. The tensile strength test showed a fracture at the intermetallic layer when the tensile strength is 225.9 MPa. The tensile value test indicated the average of welds was equivalent to the 85% tensile strength of the A5052 aluminum alloy. The thickness of the intermetallic layers is non-uniform at different positions with the ranges from 1.95 to 5 μm. The quality of the butt joint is better if the intermetallic layer is minimized. The Si crystals which appeared at the welding seam, indicating that this element participated actively during the welding process, also contributed to the IMC layer's formation.

Experimental and numerical study of spatter formation and composition change in fiber laser welding of aluminum alloy

NASA Astrophysics Data System (ADS)

Wu, Dongsheng; Hua, Xueming; Ye, Youxiong; Huang, Lijin; Li, Fang; Huang, Ye

2018-05-01

A laser welding experiment with glass is conducted to directly observe the keyhole behavior and spatter formation in fiber laser welding of aluminum alloy. A 3D model is developed to investigate the spatter formation and composition change. An additional conservation equation is introduced to describe the Mg element distribution, and the Mg element loss due to evaporation is also considered. Based on numerical and experimental results, it is found that the keyhole geometry in laser welding of aluminum alloy is different from that in laser welding of steel. There are three required steps for spatter formation around the keyhole. The high momentum of the molten metal, the high recoil pressure and vapor shear stress, and the low surface tension around the keyhole contribute to the easy formation of spatter. The in-homogeneous distribution of Mg element in the weld can be attributable to the continuous evaporation of Mg element at the top surface of keyhole rear, the upward flow of low Mg element region from the bottom of the keyhole to the top surface of keyhole rear along the fusion line, the collapse of the keyhole, and the ejection of spatters.

Flaw growth behavior in thick welded plates of 2219-T87 aluminum at room and cryogenic temperatures

NASA Technical Reports Server (NTRS)

Forman, R. G.; Glorioso, S. V.; Medlock, J. D.

1973-01-01

Axial load fatigue and fracture tests were conducted on thick welded plates of 2219-T87 aluminum alloy to determine the tensile strength properties and the flaw growth behavior in electron beam, gas metal arc, and pulse current gas tungsten arc welds for plates 6.35 centimeters (2.5 in.) thick. The tests were conducted in room temperature air and in liquid nitrogen environments. Specimens were tested in both the as-welded and the aged after welding conditions. The experimental crack growth rate were correlated with theoretical crack growth rate predictions for semielliptical surface flaws.

Thermal Management in Friction-Stir Welding of Precipitation-Hardening Aluminum Alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Upadhyay, Piyush; Reynolds, Anthony

2015-05-25

Process design and implementation in FSW is mostly dependent on empirical information gathered through experience. Basic science of friction stir welding and processing can only be complete when fundamental interrelationships between process control parameters and response variables and resulting weld microstructure and properties are established to a reasonable extent. It is known that primary process control parameters like tool rotation and translation rate and forge axis force have complicated and interactive relationships to the process response variables such as peak temperature, time at temperature etc. Of primary influence to the other process response parameters are temperature and its gradient atmore » the deformation and heat affected zones. Through review of pertinent works in the literature and some experimental results from boundary condition work performed in precipitation hardening aluminum alloys this paper will partially elucidate the nature and effects of temperature transients caused by variation of thermal boundaries in Friction Stir Welding.« less

Influences of post weld heat treatment on tensile strength and microstructure characteristics of friction stir welded butt joints of AA2014-T6 aluminum alloy

NASA Astrophysics Data System (ADS)

Rajendran, C.; Srinivasan, K.; Balasubramanian, V.; Balaji, H.; Selvaraj, P.

2016-08-01

Friction stir welded (FSWed) joints of aluminum alloys exhibited a hardness drop in both the advancing side (AS) and retreating side (RS) of the thermo-mechanically affected zone (TMAZ) due to the thermal cycle involved in the FSW process. In this investigation, an attempt has been made to overcome this problem by post weld heat treatment (PWHT) methods. FSW butt (FSWB) joints of Al-Cu (AA2014-T6) alloy were PWHT by two methods such as simple artificial aging (AA) and solution treatment followed by artificial aging (STA). Of these two treatments, STA was found to be more beneficial than the simple aging treatment to improve the tensile properties of the FSW joints of AA2014 aluminum alloy.

Theoretical Foundation for Weld Modeling

NASA Technical Reports Server (NTRS)

Traugott, S.

1986-01-01

Differential equations describe physics of tungsten/inert-gas and plasma-arc welding in aluminum. Report collects and describes necessary theoretical foundation upon which numerical welding model is constructed for tungsten/inert gas or plasma-arc welding in aluminum without keyhole. Governing partial differential equations for flow of heat, metal, and current given, together with boundary conditions relevant to welding process. Numerical estimates for relative importance of various phenomena and required properties of 2219 aluminum included

Ultrasonic Spot and Torsion Welding of Aluminum to Titanium Alloys: Process, Properties and Interfacial Microstructure

NASA Astrophysics Data System (ADS)

Balle, Frank; Magin, Jens

Hybrid lightweight structures shape the development of future vehicles in traffic engineering and the aerospace industry. For multi-material concepts made out of aluminum and titanium alloys, the ultrasonic welding technique is an alternative effective joining technology. The overlapped structures can be welded in the solid state, even without gas shielding. In this paper the conventional ultrasonic spot welding with longitudinal oscillation mode is compared to the recent ultrasonic torsion welding with a torsional mode at 20 kHz working frequency. For each technique the process parameters welding force, welding energy and oscillation amplitude were optimized for the hybrid joints using design of experiments. Relationships between the process parameters, mechanical properties and related welding zone should be understood. Central aspects of the research project are microscopic studies of the joining zone in cross section and extensive fracture surface analysis. Detailed electron microscopy and spectroscopy of the hybrid interface help to understand the interfacial formation during ultrasonic welding as well as to transfer the gained knowledge for further multi-metal joints.

Design, fabrication and test of a hydrogen heat pipe. [extruding and grooving 6063-T6 aluminum tubes for cryogenic heat pipes

NASA Technical Reports Server (NTRS)

Alario, J.

1979-01-01

Re-entrant groove technology was extended to hydrogen heat pipes. Parametric analyses are presented which optimize the theoretical design while considering the limitations of state-of-the-art extrusion technology. The 6063-T6 aluminum extrusion is 14.6 mm OD with a wall thickness of 1.66 mm and contains 20 axial grooves which surround a central 9.3 mm diameter vapor core. Each axial groove is 0.775 mm diameter with a 0.33 mm opening. An excess vapor reservoir is provided at the evaporator to minimize the pressure containment hazard during ambient storage. Modifications to the basic re-entrant groove profile resulted in improved overall performance. While the maximum heat transport capacity decreased slightly to 103 w-m the static wicking height increased markedly to 4.5 cm. The heat pipe became operational between 20 and 30 K after a cooldown from 77 K without any difficulty. Steady state performance data taken over a 19 to 23 K temperature range indicated: (1) maximum heat transport capacity of 5.4 w-m; (2) static wicking height of 1.42 cm; and (3) overall heat pipe conductance of 1.7 watts/deg C.

Microstructural Characteristics and Mechanical Properties of Friction Stir Welded Thick 5083 Aluminum Alloy

NASA Astrophysics Data System (ADS)

Imam, Murshid; Sun, Yufeng; Fujii, Hidetoshi; Ma, Ninshu; Tsutsumi, Seiichiro; Murakawa, Hidekazu

2017-01-01

Joining thick sections of aluminum alloys by friction stir welding (FSW) in a single pass needs to overcome many challenges before it comes to full-scale industrial use. Important parameters controlling the structure-properties relationships both across weld cross-section and through thickness direction were investigated through mechanical testing, electron backscatter diffraction technique, transmission electron microscopy, and occurrence of serrated plastic flow. The evolution of the properties in the weld cross-section shows that the presence of undissolved and fragmented Al_6MnFe particles cause discrepancies in establishing the Hall-Petch relationship, and derive the strengthening from the Orowan strengthening mechanism. A `stop action' friction stir weld has been prepared to understand the role of geometrical features of the tool probe in the development of the final microstructure after complete weld. Sectioning through the `stop action' weld with the probe in situ displays the individual effect of thread and flat on the grain structure formation. The material at the thread surface experiences more severe deformation than the material at flat surface. Both the high-angle boundaries and mean grain size are found to be higher at the thread surface. The strain hardening capacity, stress serration amplitude, and frequency are observed to be higher in the stir zone than other weld regions.

Microstructure and Residual Stress Distributions Under the Influence of Welding Speed in Friction Stir Welded 2024 Aluminum Alloy

NASA Astrophysics Data System (ADS)

Moghadam, Danial Ghahremani; Farhangdoost, Khalil; Nejad, Reza Masoudi

2016-06-01

Friction stir welding was conducted on 8-mm-thick plates made of AA2024-T351 aluminum alloy at tool traverse speeds between 8 and 31.5 mm/minutes and tool rotational speed between 400 and 800 rpm. Metallographic analyses and mechanical tests including hardness, tensile, residual stress, and fracture toughness tests were carried out to evaluate the microstructural and mechanical properties of the joints as a function of the process parameters. The finite element simulation of the FSW process was also performed using a thermal model. The hardness test results show that the increase in rotational speed or decrease in traverse speed of the tool would cause a decrease in weld zone hardness. The best tensile properties are obtained at rotational/traverse speed ratio between 20 and 32. Also, the longitudinal residual stress profiles were evaluated by employing X-ray diffraction method. The numerical and experimental results showed that the increase in a traverse or rotational speed would increase the residual stress of the weld zone. From the fracture toughness results, it was found that the welding process decreases the joints fracture toughness 18 to 49 pct with respect to the base metal.

A Vision-Aided 3D Path Teaching Method before Narrow Butt Joint Welding.

PubMed

Zeng, Jinle; Chang, Baohua; Du, Dong; Peng, Guodong; Chang, Shuhe; Hong, Yuxiang; Wang, Li; Shan, Jiguo

2017-05-11

For better welding quality, accurate path teaching for actuators must be achieved before welding. Due to machining errors, assembly errors, deformations, etc., the actual groove position may be different from the predetermined path. Therefore, it is significant to recognize the actual groove position using machine vision methods and perform an accurate path teaching process. However, during the teaching process of a narrow butt joint, the existing machine vision methods may fail because of poor adaptability, low resolution, and lack of 3D information. This paper proposes a 3D path teaching method for narrow butt joint welding. This method obtains two kinds of visual information nearly at the same time, namely 2D pixel coordinates of the groove in uniform lighting condition and 3D point cloud data of the workpiece surface in cross-line laser lighting condition. The 3D position and pose between the welding torch and groove can be calculated after information fusion. The image resolution can reach 12.5 μm. Experiments are carried out at an actuator speed of 2300 mm/min and groove width of less than 0.1 mm. The results show that this method is suitable for groove recognition before narrow butt joint welding and can be applied in path teaching fields of 3D complex components.

Optimization of Equipment and Techniques for Welding Aluminum in the Thickness Range of About 1/16 to 1/4 Inch

DTIC Science & Technology

1975-09-29

no D AD-AO16 837 OPTIMIZATION OF EQUIPMENT AND TECHNIQUES FOR WELDING ALUMINUM IN THE THICKNESS RANGE OF ABOUT 1/16 TO 1/4 INCH Richard K. Sager, et...TECHNIQUES FOR WELDING ALUMINUM IN THE THICKNESS RANGE OF ABOUT 6~ TO ’i INCH by Richard K Sager Paul B Dickerson James E Grant Walter R Reichelt Maurice C...SharpMByron Shurnaker 0 Contract No N0024-74-C 5502 *,j Issued by NAVAL SEA SYSTEM COMMAND Project Serial No SF 541-702 Task 17016 FINAL REPORT Richard

Effect of tool pin features on process response variables during friction stir welding of dissimilar aluminum alloys

DOE PAGES

Rabby, Reza; Tang, Wei; Reynolds, A. P.

2015-05-13

In this article, the effect of pin features and orientation/placement of the materials on advancing side were investigated for friction stir welding (FSW) of dissimilar aluminum alloys AA2050 and AA6061. Pins for FSW were produced with a 2.12 mm pitch thread having three flats/flutes. Three sets of rotational speed/welding speed were used to perform a series of welds in a butt joint arrangement. The results show that, joint quality, process response variables and welding temperature are highly affected by pin features and material orientation in FSW. Defect free joints with effective material transportation in the weld nugget zone were obtainedmore » when welding was performed with AA2050 on the advancing side. The tool also encounters less in-plane reaction force for welding with 2050 on the advancing side. Pin with thread+3 flats produces quality welds at low rotational and travel speed regardless of the location of alloys on advancing or retreating side.« less

Effect of tool pin features on process response variables during friction stir welding of dissimilar aluminum alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rabby, Reza; Tang, Wei; Reynolds, A. P.

In this article, the effect of pin features and orientation/placement of the materials on advancing side were investigated for friction stir welding (FSW) of dissimilar aluminum alloys AA2050 and AA6061. Pins for FSW were produced with a 2.12 mm pitch thread having three flats/flutes. Three sets of rotational speed/welding speed were used to perform a series of welds in a butt joint arrangement. The results show that, joint quality, process response variables and welding temperature are highly affected by pin features and material orientation in FSW. Defect free joints with effective material transportation in the weld nugget zone were obtainedmore » when welding was performed with AA2050 on the advancing side. The tool also encounters less in-plane reaction force for welding with 2050 on the advancing side. Pin with thread+3 flats produces quality welds at low rotational and travel speed regardless of the location of alloys on advancing or retreating side.« less

CHARACTERIZATION OF DEFECTS IN ALLOY 152, 52 AND 52M WELDS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bruemmer, Stephen M.; Toloczko, Mychailo B.; Olszta, Matthew J.

2009-08-27

distributions, defect characteristics and weld residual strains were examined by optical metallography, scanning electron microscopy, electron backscatter diffraction and transmission electron microscopy. Industry-supplied mock-up welds were characterized including alloy 52 and 152 weldments, alloy 52M overlay and inlay welds, and an alloy 52 overlay. II. WELDMENTS II.A. Alloy 52 and 152 Weld Mockups The alloy 52 and 152 weld mockups were fabricated by MHI for the Kewaunee reactor and were obtained from the EPRI NDE Center. The mockups were U-groove welds joining two plates of 304SS as shown in Figure 1. Alloy 152 butter (heat 307380) was placed on the U-groove surface for both mockups by shielded metal arc welding (SMAW). For the alloy 152 weld mockup, the alloy 152 fill (heat 307380) was also applied using SMAW while for the alloy 52 weld mockup, the alloy 52 fill (heat NX2686JK) was applied using gas tungsten arc welding (GTAW). Welding parameters for the fill materials were substantially different with the alloy 152 SMAW having a deposition speed of 4-25 cm/min with a current of 95-145 A and the alloy 52 GTAW having a deposition speed of 4-10 cm/min with a current of 150-300 A. One prominent feature in these mockup welds is the presence of a crack starting at the 304SS butt joint at the bottom of the U-groove and extending up into the weld. It appears that the 304SS plate on either side of the butt joint acted as an anchor for the weld resulting in a stress rise across the slit that drove crack formation and extension up into the fill weld. As will be shown in the next section, the extent of the cracking around this stress riser was much greater in the MHI 52 weld mockup.« less

Friction Stir Welding in Wrought and Cast Aluminum Alloys: Weld Quality Evaluation and Effects of Processing Parameters on Microstructure and Mechanical Properties

NASA Astrophysics Data System (ADS)

Pan, Yi; Lados, Diana A.

2017-04-01

Friction stir welding (FSW) is a solid-state process widely used for joining similar and dissimilar materials for critical applications in the transportation sector. Understanding the effects of the process on microstructure and mechanical properties is critical in design for structural integrity. In this study, four aluminum alloy systems (wrought 6061-T651 and cast A356, 319, and A390) were processed in both as-fabricated and pre-weld heat-treated (T6) conditions using various processing parameters. The effects of processing and heat treatment on the resulting microstructures, macro-/micro-hardness, and tensile properties were systematically investigated and mechanistically correlated to changes in grain size, characteristic phases, and strengthening precipitates. Tensile tests were performed at room temperature both along and across the welding zones. A new method able to evaluate weld quality (using a weld quality index) was developed based on the stress concentration calculated under tensile loading. Optimum processing parameter domains that provide both defect-free welds and good mechanical properties were determined for each alloy and associated with the thermal history of the process. These results were further related to characteristic microstructural features, which can be used for component design and materials/process optimization.

Occupational exposure to aluminum and its biomonitoring in perspective.

PubMed

Riihimäki, Vesa; Aitio, Antero

2012-11-01

Exposure to aluminum at work is widespread, and people are exposed to several species of aluminum, which differ markedly as to the kinetics and toxicity. Especially welding of aluminum is widely applied and continuously expanding. Inhalation of fine particles of sparsely soluble aluminum results in the retention of deposited particles in the lungs. From the lungs, aluminum is released to the blood and distributed to bones and the brain, and excreted to urine. Soluble aluminum compounds are not accumulated in the lungs. Neurotoxicity is the critical effect of exposure to sparsely soluble aluminum compounds. Studies on workers exposed to aluminum welding fumes have revealed disturbances of cognitive processes, memory and concentration, and changes in mood and EEG. Early pulmonary effects have been observed among aluminum powder-production workers using high-resolution computed tomography. The primary objective of aluminum biomonitoring (BM) is to help prevent the formation of aluminum burden in the lungs and thereby to prevent harmful accumulation of aluminum in target organs. BM of aluminum can be effectively used for this purpose in the production/use of aluminum powders, aluminum welding, as well as plasma cutting, grinding, polishing and thermal spraying of aluminum. BM of aluminum may also be similarly useful in the smelting of aluminum and probably in the production of corundum. BM can help identify exposed individuals and roughly quantitate transient exposure but cannot predict health effects in the production/use of soluble aluminum salts. For urinary aluminum (U-Al) we propose an action limit of 3 µmol/L, corrected to a relative density of 1.021, in a sample collected preshift after two days without occupational exposure, and without use of aluminum-containing drugs. This value corresponds roughly to 2.3 µmol/g creatinine. Compliance with this limit is expected to protect the worker against the critical effect of aluminum in exposure to sparsely soluble

Improved TIG weld joint strength in aluminum alloy 2219-T87 by filler metal substitution

NASA Technical Reports Server (NTRS)

Poorman, R. M.; Lovoy, C. V.

1972-01-01

The results of an investigation on weld joint characteristics of aluminum alloy 2219-T87 are given. Five different alloys were utilized as filler material. The mechanical properties of the joints were determined at ambient and cryogenic temperatures for weldments in the as-welded condition and also, for weldments after elevated temperature exposures. Other evaluations included hardness surveys, stress corrosion susceptibility, and to a limited extent, the internal metallurgical weld structures. The overall results indicate that M-943 filler weldments are superior in strength to weldments containing either the standard 2319 filler or fillers 2014, 2020, and a dual wire feed consisting of three parts 2319 and one part 5652. In addition, no deficiencies were evident in M-934 filler weldments with regard to ductility, joint strength after elevated temperature exposure, weld hardness, metallographic structures, or stress corrosion susceptibility.

A Fundamental Study of Laser Beam Welding Aluminum-Lithium Alloy 2195 for Cryogenic Tank Applications

NASA Technical Reports Server (NTRS)

Martukanitz, R. P.; Jan. R.

1996-01-01

Based on the potential for decreasing costs of joining stiffeners to skin by laser beam welding, a fundamental research program was conducted to address the impediments identified during an initial study involving laser beam welding of aluminum-lithium alloys. Initial objectives of the program were the identification of governing mechanism responsible for process related porosity while establishing a multivariant relationship between process parameters and fusion zone geometry for laser beam welds of alloy 2195. A three-level fractional factorial experiment was conducted to establish quantitative relationships between primary laser beam processing parameters and critical weld attributes. Although process consistency appeared high for welds produced during partial completion of this study, numerous cracks on the top-surface of the welds were discovered during visual inspection and necessitated additional investigations concerning weld cracking. Two experiments were conducted to assess the effect of filler alloy additions on crack sensitivity: the first experiment was used to ascertain the effects of various filler alloys on cracking and the second experiment involved modification to process parameters for increasing filler metal dilution. Results indicated that filler alloys 4047 and 4145 showed promise for eliminating cracking.

Friction Stir Welding of SiC/Aluminum Metal Matrix Composites

NASA Technical Reports Server (NTRS)

Lee, Jonathan A.

1999-01-01

Friction Stir Welding (FSW) is a new solid state process for joining metals by plasticizing and consolidating materials around the bond line using thermal energy producing from frictional forces. A feasibility study for FSW of Metal Matrix Composites (MMC) was investigated using aluminum 6092 alloy reinforced with 17% SiC particulates. FSW process consists of a special rotating pin tool that is positioned to plunge into the MMC surface at the bond line. As the tool rotates and move forward along the bond line, the material at the bond line is heated up and forced to flow around the rotating tip to consolidate on the tip's backside to form a solid state joint. FSW has the potential for producing sound welds with MMC because the processing temperature occurs well below the melting point of the metal matrix; thereby eliminating the reinforcement-to-matrix solidification defects, reducing the undesirable chemical reactions and porosity problems.

Gas tungsten arc welding of aluminum alloys 1XXX and 3003 to 3004, 5052 and 5X54. Welding procedure specification

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wodtke, C.H.; Frizzell, D.R.; Plunkett, W.A.

1985-08-01

Procedure WPS-2201 is qualified under Section IX of the ASME Boiler and Pressure Vessel for gas tungsten arc welding of aluminum alloys 1060, 1100, and 3003 (P-21) to 3004, 5052, 5154, and 5454 (P-22), in thickness range 0.062 to 0.5 in.; filler metal is ER5356 (F-22); shielding gas is argon.

A Vision-Aided 3D Path Teaching Method before Narrow Butt Joint Welding

PubMed Central

Zeng, Jinle; Chang, Baohua; Du, Dong; Peng, Guodong; Chang, Shuhe; Hong, Yuxiang; Wang, Li; Shan, Jiguo

2017-01-01

For better welding quality, accurate path teaching for actuators must be achieved before welding. Due to machining errors, assembly errors, deformations, etc., the actual groove position may be different from the predetermined path. Therefore, it is significant to recognize the actual groove position using machine vision methods and perform an accurate path teaching process. However, during the teaching process of a narrow butt joint, the existing machine vision methods may fail because of poor adaptability, low resolution, and lack of 3D information. This paper proposes a 3D path teaching method for narrow butt joint welding. This method obtains two kinds of visual information nearly at the same time, namely 2D pixel coordinates of the groove in uniform lighting condition and 3D point cloud data of the workpiece surface in cross-line laser lighting condition. The 3D position and pose between the welding torch and groove can be calculated after information fusion. The image resolution can reach 12.5 μm. Experiments are carried out at an actuator speed of 2300 mm/min and groove width of less than 0.1 mm. The results show that this method is suitable for groove recognition before narrow butt joint welding and can be applied in path teaching fields of 3D complex components. PMID:28492481

Effect of current and speed on porosity in autogenous Tungsten Inert Gas (TIG) welding of aluminum alloys A1100 butt joint

NASA Astrophysics Data System (ADS)

Milyardi, Indra; Sunar Baskoro, Ario

2018-04-01

Autogenous Tungsten Inert Gas (TIG) welding has been conducted on aluminum alloy A1100. The purpose of this research is to determine the proper current and speed of autogenous TIG welding with butt joint pattern. Variations on welding current are 150 A, 155 A, and 160 A with the variations on welding speed are 1 mm/seconds, 1.1 mm/seconds, 1.2 mm/seconds. The welded results were tested using non-destructive test (NDT) method using X-Ray radiography. After the test, it is found that the appropriate current for the best result without porosity can be achieved using the welding parameter of welding current of 160 A and the welding speed of 1.1 mm seconds.

Mechanical Property Analysis in the Retracted Pin-Tool (RPT) Region of Friction Stir Welded (FSW) Aluminum Lithium 2195

NASA Technical Reports Server (NTRS)

Ding, R. Jeffrey; Oelgoetz, Peter A.

1999-01-01

The "Auto-Adjustable Pin Tool for Friction Stir Welding", was developed at The Marshall Space Flight Center to address process deficiencies unique to the FSW process. The auto-adjustable pin tool, also called the retractable pin-tool (R.PT) automatically withdraws the welding probe of the pin-tool into the pin-tool's shoulder. The primary function of the auto-adjustable pin-tool is to allow for keyhole closeout, necessary for circumferential welding and localized weld repair, and, automated pin-length adjustment for the welding of tapered material thickness. An overview of the RPT hardware is presented. The paper follows with studies conducted using the RPT. The RPT was used to simulate two capabilities; welding tapered material thickness and closing out the keyhole in a circumferential weld. The retracted pin-tool regions in aluminum- lithium 2195 friction stir weldments were studied through mechanical property testing and metallurgical sectioning. Correlation's can be =de between retractable pin-tool programmed parameters, process parameters, microstructure, and resulting weld quality.

Dissimilar Impact Welding of 6111-T4, 5052-H32 Aluminum Alloys to 22MnB5, DP980 Steels and the Structure-Property Relationship of a Strongly Bonded Interface

NASA Astrophysics Data System (ADS)

Liu, Bert; Vivek, Anupam; Presley, Michael; Daehn, Glenn S.

2018-03-01

The ability to weld high-strength aluminum to high-strength steel is highly desired for vehicle lightweighting but difficult to attain by conventional means. In this work, vaporizing foil actuator welding was used to successfully weld four Al/Fe combinations consisting of high-strength alloys: AA5052-H32, AA6111-T4, DP980, and 22MnB5. Flyer velocities up to 727 m/s were reached using 10 kJ input energy. In lap-shear testing, samples primarily failed in base aluminum near the aluminum's native strength, showing that the welds were stronger than a base metal and that the base metal was not significantly weakened by the welding process. A particularly strong weld area was studied by transmission electron microscopy to shed light on the microstructural features of strong impact welds. It was found to be characterized by a continuously bonded, fully crystalline interface, extremely fine (nanoscale) grains, mesoscopic as well as microscopic wavy features, and lack of large continuous intermetallic compounds.

Multiple pass and multiple layer friction stir welding and material enhancement processes

DOEpatents

Feng, Zhili [Knoxville, TN; David, Stan A [Knoxville, TN; Frederick, David Alan [Harriman, TN

2010-07-27

Processes for friction stir welding, typically for comparatively thick plate materials using multiple passes and multiple layers of a friction stir welding tool. In some embodiments a first portion of a fabrication preform and a second portion of the fabrication preform are placed adjacent to each other to form a joint, and there may be a groove adjacent the joint. The joint is welded and then, where a groove exists, a filler may be disposed in the groove, and the seams between the filler and the first and second portions of the fabrication preform may be friction stir welded. In some embodiments two portions of a fabrication preform are abutted to form a joint, where the joint may, for example, be a lap joint, a bevel joint or a butt joint. In some embodiments a plurality of passes of a friction stir welding tool may be used, with some passes welding from one side of a fabrication preform and other passes welding from the other side of the fabrication preform.

Gas tungsten arc welding of aluminum alloys 6XXX. Welding procedure specification. Supplement 1. Records of procedure qualification tests. [6061 and 6063

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wodtke, C.H.; Frizzell, D.R.; Plunkett, W.A.

1986-06-01

Procedure WPS-1003 is qualified under Section IX of the ASME Boiler and Pressure Vessel Code for gas tungsten arc welding of aluminum alloys 6061 and 6063 (P-23), in thickness range 0.035 to 0.516 inch; filler metal is ER4043 (F-23) or ER5356 (F-22); shielding gas is argon.

Dye penetrant indications caused by superficial surface defects in 2014 aluminum alloy welds.

NASA Technical Reports Server (NTRS)

Hocker, R. G.; Wilson, K. R.

1971-01-01

Demonstration that dye penetrant indications on the heat-affected zone of 2014-T6 aluminum GMA weldments are frequently caused by superficial surface conditions and are less than 0.007 in. deep. The following methods are suggested for minimization of these surface defects: stabilization of the arc, application of dc ?GTA' welding procedures, reduction of the caustic etch time, and use of fine grain materials.

Thermal Management in Friction-Stir Welding of Precipitation-Hardened Aluminum Alloys

NASA Astrophysics Data System (ADS)

Upadhyay, Piyush; Reynolds, Anthony P.

2015-05-01

Process design and implementation in friction-stir welding (FSW) is mostly dependent on empirical information. Basic science of FSW and processing can only be complete when fundamental interrelationships between the process control parameters and response variables and the resulting weld microstructure and properties are established to a reasonable extent. It is known that primary process control parameters such as tool rotation, translation rates, and forge axis force have complicated and interactive relationships to process-response variables such as peak temperature and time at temperature. Of primary influence on the other process-response parameters are temperature and its gradient in the deformation and heat-affected zones. Through a review of pertinent works in the literature and results from boundary condition experiments performed in precipitation-hardening aluminum alloys, this article partially elucidates the nature and effects of temperature transients caused by variation of thermal boundaries in FSW.

Special Features of Structure Formation in an Explosion-Welded Magnesium-Aluminum Composite Under Deformation and Subsequent Heat Treatment

NASA Astrophysics Data System (ADS)

Gurevich, L. M.; Arisova, V. N.; Trykov, Yu. P.; Ponomareva, I. A.; Trudov, A. F.

2016-07-01

The effect of bending deformation and subsequent heat treatment on the variation of microhardness and structure of explosion-welded magnesium-aluminum layered composite material MA2-1 - AD1 is studied.

Effects of fabrication procedures and weld melt-through on fatigue resistance of orthotropic steel deck welds.

DOT National Transportation Integrated Search

2008-12-01

A common practice for the fabrication of orthotropic bridge deck in the US involves using 80% partial-joint-penetration groove welds (PJP) to join : closed ribs to a deck plate. Avoiding weld melt-through with the thin rib plate may be difficult to a...

Experimental Research on Fatigue Failure for 2219-T6 Aluminum Alloy Friction Stir-Welded Joints

NASA Astrophysics Data System (ADS)

Sun, Guo-Qin; Niu, Jiang-Pei; Chen, Ya-Jing; Sun, Feng-Yang; Shang, De-Guang; Chen, Shu-Jun

2017-08-01

The fatigue experiment was executed for the 2219-T6 aluminum alloy friction stir-welded joints at the rotation speed of 800 r/min and the welding velocity of 150 mm/min. Most fatigue failures occurred in the weld nugget zone (WNZ), the thermo-mechanical affected zone and the nearby areas. The experimental results demonstrated that the sudden hardness gradient increases sites corresponding to the fatigue failure locations. The high-angle grain boundaries with the highest concentration were scattered within the WNZ. The microcracks initiated at the intersection of the soft grains. More than one crack initiation site was observed within the WNZ and the thermo-mechanical affected zone, when the fracture occurred in these areas. The rough surface of the welding area should be one of the main reasons for the fatigue failure occurrence. The fatigue crack growth rate in the WNZ at the first stage was fastest in comparison with the fatigue crack growth rate in the other areas of the joint.

Nondestructive Evaluation of Friction Stir-Welded Aluminum Alloy to Coated Steel Sheet Lap Joint

NASA Astrophysics Data System (ADS)

Das, H.; Kumar, A.; Rajkumar, K. V.; Saravanan, T.; Jayakumar, T.; Pal, Tapan Kumar

2015-11-01

Dissimilar lap joints of aluminum sheet (AA 6061) of 2 mm thickness and zinc-coated steel sheet of 1 mm thickness were produced by friction stir welding with different combinations of rotational speed and travel speed. Ultrasonic C- and B-scanning, and radiography have been used in a complementary manner for detection of volumetric (cavity and flash) and planar (de bond) defects as the defects are in micron level. Advanced ultrasonic C-scanning did not provide any idea about the defects, whereas B-scanning cross-sectional image showed an exclusive overview of the micron-level defects. A digital x-ray radiography methodology is proposed for quality assessment of the dissimilar welds which provide three-fold increase in signal-to-noise ratio with improved defect detection sensitivity. The present study clearly shows that the weld tool rotational speed and travel speed have a decisive role on the quality of the joints obtained by the friction stir welding process. The suitability of the proposed NDE techniques to evaluate the joint integrity of dissimilar FSW joints is thus established.

Material Interactions in a Novel Pinless Tool Approach to Friction Stir Spot Welding Thin Aluminum Sheet

NASA Astrophysics Data System (ADS)

Bakavos, Dimitrios; Chen, Yingchun; Babout, Laurent; Prangnell, Phil

2011-05-01

The requirement for a probe, or pin, in friction stir spot welding (FSSW) leads to an undesirable keyhole and "hooking," which can influence the fracture path and weld strength. Furthermore, the full weld cycle for FSSW is typically longer than ideal for the automotive industry, being 2 to 5 seconds. Here, it is shown that using a novel pinless tool design it is possible to achieve high lap shear strength (~3.4 kN) in thin aluminum sheet (~1 mm thick), with short weld cycle times (<1 second). Several techniques have been exploited to study the material flow and mechanisms of weld formation in pinless FSSW, including high-resolution X-ray tomography, to understand the role of the tool design and weld parameters. Despite the "simple" nature of a pinless tool, material flow in the weld zone was found to be surprisingly complex and strongly influenced by surface features on the tool, which greatly increased the penetration of the plastic zone into the bottom sheet. Because of the rapid thermal cycle and high level of grain refinement, the weld zone was found to develop a higher strength than the parent material with little evidence of a heat affected zone (HAZ) after postweld natural aging.

B218 Weld Filler Wire Characterization for Al-Li Alloy 2195

NASA Technical Reports Server (NTRS)

Bjorkman, Gerry; Russell, Carolyn

2000-01-01

NASA Marshall Space Flight Center, Lockheed Martin Space Systems- Michoud Operations, and McCook Metals have developed an aluminum-copper weld filler wire for fusion welding aluminum lithium alloy 2195. The aluminum-copper based weld filler wire has been identified as B218, a McCook Metals designation. B218 is the result of six years of weld filler wire development funded by NASA, Lockheed Martin, and McCook Metals. The filler wire chemistry was developed to produce enhanced 2195 weld and repair weld mechanical properties over the 4043 aluminum-silicon weld filler wire, which is currently used to weld 2195 on the Super Lightweight External Tank for the NASA Space Shuttle Program. An initial characterization was performed consisting of a repair weld evaluation using B218 and 4043 weld filler wires. The testing involved room temperature and cryogenic repair weld tensile testing along with fracture toughness testing. From the testing, B218 weld filler wire produce enhanced repair weld tensile strength, ductility, and fracture properties over 4043. B218 weld filler wire has proved to be a superior weld filler wire for welding aluminum lithium alloy 2195 over 4043.

Study of mechanical joint strength of aluminum alloy 7075-T6 and dual phase steel 980 welded by friction bit joining and weld-bonding under corrosion medium

DOE PAGES

Lim, Yong Chae; Squires, Lile; Pan, Tsung-Yu; ...

2014-12-30

We have employed a unique solid-sate joining process, called friction bit joining (FBJ), to spot weld aluminum alloy (AA) 7075-T6 and dual phase (DP) 980 steel. Static joint strength was studied in the lap shear tension configuration. In addition, weld-bonding (adhesive + FBJ) joints were studied in order to evaluate the ability of adhesive to mitigate the impact of corrosion on joint properties. Accelerated laboratory cyclic corrosion tests were carried out for both FBJ only and weld-bonding joints. Furthermore, the FBJ only joints that emerged from corrosion testing had lap shear failure loads that were significantly lower than freshly preparedmore » joints. However, weld-bonding specimens retained more than 80% of the lap shear failure load of the freshly prepared weld-bonding specimens. Moreover, examination of joint cross sections confirmed that the presence of adhesive in the weld-bonding joints mitigated the effect of the corrosion environment, compared to FBJ only joints.« less

Fabrication of Aluminum Foam-Filled Thin-Wall Steel Tube by Friction Welding and Its Compression Properties.

PubMed

Hangai, Yoshihiko; Saito, Masaki; Utsunomiya, Takao; Kitahara, Soichiro; Kuwazuru, Osamu; Yoshikawa, Nobuhiro

2014-09-19

Aluminum foam has received considerable attention in various fields and is expected to be used as an engineering material owing to its high energy absorption properties and light weight. To improve the mechanical properties of aluminum foam, combining it with dense tubes, such as aluminum foam-filled tubes, was considered necessary. In this study, an aluminum foam-filled steel tube, which consisted of ADC12 aluminum foam and a thin-wall steel tube, was successfully fabricated by friction welding. It was shown that a diffusion bonding layer with a thickness of approximately 10 μm was formed, indicating that strong bonding between the aluminum foam and the steel tube was realized. By the X-ray computed tomography observation of pore structures, the fabrication of an aluminum foam-filled tube with almost uniform pore structures over the entire specimen was confirmed. In addition, it was confirmed that the aluminum foam-filled steel tube exhibited mechanical properties superior to those of the ADC12 aluminum foam and steel tube. This is considered to be attributed to the combination of the aluminum foam and steel tube, which particularly prevents the brittle fracture and collapse of the ADC12 foam by the steel tube, along with the strong metal bonding between the aluminum foam and the steel tube.

Characterization of disk-laser dissimilar welding of titanium alloy Ti-6Al-4V to aluminum alloy 2024

NASA Astrophysics Data System (ADS)

Caiazzo, Fabrizia; Alfieri, Vittorio; Cardaropoli, Francesco; Corrado, Gaetano; Sergi, Vincenzo

2013-02-01

Both technical and economic reasons suggest to join dissimilar metals, benefiting from the specific properties of each material in order to perform flexible design. Adhesive bonding and mechanical joining have been traditionally used although adhesives fail to be effective in high-temperature environments and mechanical joining are not adequate for leak-tight joints. Friction stir welding is a valid alternative, even being difficult to perform for specific joint geometries and thin plates. The attention has therefore been shifted to laser welding. Interest has been shown in welding titanium to aluminum, especially in the aviation industry, in order to benefit from both corrosive resistance and strength properties of the former, and low weight and cost of the latter. Titanium alloy Ti-6Al-4V and aluminum alloy 2024 are considered in this work, being them among the most common ones in aerospace and automotive industries. Laser welding is thought to be particularly useful in reducing the heat affected zones and providing deep penetrative beads. Nevertheless, many challenges arise in welding dissimilar metals and the aim is further complicated considering the specific features of the alloys in exam, being them susceptible to oxidation on the upper surface and porosity formation in the fused zone. As many variables are involved, a systematic approach is used to perform the process and to characterize the beads referring to their shape and mechanical features, since a mixture of phases and structures is formed in the fused zone after recrystallization.

Effect of welding position on porosity formation in aluminum alloy welds

NASA Technical Reports Server (NTRS)

Haryung, J.; Wroth, R. S.

1967-01-01

Program investigates the effects of varied welding positions on weld qualities. Progressive changes in bead geometry occur as the weld plane angle is varied from upslope to downslope. The gravitational effect on the weld puddle varies greatly with welding position.

Automatic hot wire GTA welding of pipe offers speed and increased deposition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sykes, I.; Digiacomo, J.

1995-07-01

Heavy-wall pipe welding for the power and petrochemical industry must meet code requirements. Contractors strive to meet these requirements in the most productive way possible. The challenge put to orbital welding equipment manufacturers is to produce pipe welding equipment that cost-effectively produces code-quality welds. Orbital welding equipment using the GTA process has long produced outstanding quality results but has lacked the deposition rate to compete cost effectively with other manual and semiautomatic processes such as SMAW, FCAW and GMAW. In recent years, significant progress has been made with the use of narrow-groove weld joint designs to reduce weld joint volumemore » and improve welding times. Astro Arc Polysoude, an orbital welding equipment manufacturer based in Sun Valley, Calif., and Nantes, France, has combined the hot wire GTAW process with orbital welding equipment using a narrow-groove weld joint design. Field test results show this process and procedure is a good alternative for many heavy-wall-pipe welding applications.« less

Microstructural variation through weld thickness and mechanical properties of peened friction stir welded 6061 aluminum alloy joints

DOE Office of Scientific and Technical Information (OSTI.GOV)

Abdulstaar, Mustafa A., E-mail: mustafa.abdulstaar

The current study examined the effect of microstructure variation on the development of mechanical properties in friction stir welded joints of 6061-T6 aluminum alloy, which were subsequently processed by shot peening (SP). Following to FSW, fatigue specimens were extracted perpendicularly to the welding direction. Surface Skimming to 0.5 mm from crown and root sides of the joint was made and SP was later applied on the two sides using ceramic shots of two different Almen intensities of 0.18 mmA and 0.24 mmA. Microstructural examination by electron back scattered diffraction (EBSD) indicated variation in the grain refinement of the weld zone,more » with coarsest grains (5 μm) at the crown side and finest grains (2 μm) at the root side. Reduction of microhardness to 60 HV occurred in the weld zone for samples in FSW condition. Application of SP promoted significant strain hardening at the crown side, with Almen intensities of 0.24 mmA providing maximum increase in microhardness to 120 HV. On the contrary, only a maximum microhardness of 75 HV was obtained at the root side. The difference in strain hardening capability at the two sides was strongly dependent on grain size. The two Almen intensities produced similar distribution of compressive residual stresses in the subsurface regions that led to enhance the fatigue strength to the level of base metal for N ≥ 10{sup 5} cycles. Yet, the increase in fatigue strength was more pronounced with increasing Almen intensity to 0.24 mmA, demonstrating further enhancement by strain hardening. - Highlights: • Grain refinement was observed after friction stir welding of AA 6061-T6. • Reduction in microhardness and fatigue strength were obtained after welding. • Variation in grain refinement led to different hardening behavior after peening. • Shot peening induced beneficial compressive residual stresses. • Shot peening and surface skimming markedly improved the fatigue performance.« less

Technology of welding aluminum alloys-IV

NASA Technical Reports Server (NTRS)

Ginez, R.; Lewis, J. R.; Millett, A. U.; Saenger, K. A.; Skelly, J. K.; Standiford, V. E.; Whiteman, J. O.

1978-01-01

Skate-weld carriage and track assembly were developed for controlled fusion welding on compound-curvature surfaces. Unlike fixed-position carriage used for vertical, horizontal, and circumferential welding, carriage has suspension system that permits angular positioning of weld head on carriage. It also has carriage-and-drive track mechanism capable of traveling over compound curvatures. Carriage is designed with universal mounting platform so that slim tools, weld heads, or X-ray units can be interchanged without need for realinement.

Upgraded HFIR Fuel Element Welding System

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sease, John D

2010-02-01

The welding of aluminum-clad fuel plates into aluminum alloy 6061 side plate tubing is a unique design feature of the High Flux Isotope Reactor (HFIR) fuel assemblies as 101 full-penetration circumferential gas metal arc welds (GMAW) are required in the fabrication of each assembly. In a HFIR fuel assembly, 540 aluminum-clad fuel plates are assembled into two nested annular fuel elements 610 mm (24-inches) long. The welding process for the HFIR fuel elements was developed in the early 1960 s and about 450 HFIR fuel assemblies have been successfully welded using the GMAW process qualified in the 1960 s. Inmore » recent years because of the degradation of the electronic and mechanical components in the old HFIR welding system, reportable defects in plate attachment or adapter welds have been present in almost all completed fuel assemblies. In October 2008, a contract was awarded to AMET, Inc., of Rexburg, Idaho, to replace the old welding equipment with standard commercially available welding components to the maximum extent possible while maintaining the qualified HFIR welding process. The upgraded HFIR welding system represents a major improvement in the welding system used in welding HFIR fuel elements for the previous 40 years. In this upgrade, the new inner GMAW torch is a significant advancement over the original inner GMAW torch previously used. The innovative breakthrough in the new inner welding torch design is the way the direction of the cast in the 0.762 mm (0.030-inch) diameter aluminum weld wire is changed so that the weld wire emerging from the contact tip is straight in the plane perpendicular to the welding direction without creating any significant drag resistance in the feeding of the weld wire.« less

Weldability of extruded aluminum-alumina composites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gedeon, S.A.; Lane, C.; Altshuller, B.

1994-12-31

Acceptable procedure were developed for welding the following types of aluminum particle-reinforced aluminum: 6061/Al{sub 2}O{sub 3}/10p-T6, 6061/Al{sub x}/O{sub 3}20p-T6, and 7005Al{sub 2}O{sub 3}/10p-T6,. Automated and manual procedures were developed and using both gas tungsten arc welding (GTAW), with a cold wire feed, and gas metal arc welding (GMAW). The effect of welding procedures on porosity, reinforcing particulate distribution, and mechanical properties was determined. Postweld heat treatment and microhardness testing were used to understand the effect of the welded microstructure on the strength and ductility of the joint. Fracture surfaces and transverse microsections of mechanical test specimens were examined to determinemore » the origins and mechanisms of failure. Cleanliness of the joint and weld wire were found to be essential to eliminate porosity. Based on these experimentally determined data, general guidelines for welding aluminum oxide particle-reinforced aluminum composites are proposed. Discussion includes proper selection of weld joint geometry, filler metals, travel speed, voltage, and current ranges. These parameters are compared to those used in an actual production environment for composite products. Distinctions between welding these composites and others produced via powder metallurgy or with silicon carbide reinforcements are also discussed.« less

Friction Stir Welding for Aluminum Metal Matrix Composites (MMC's) (Center Director's Discretionary Fund, Project No. 98-09)

NASA Technical Reports Server (NTRS)

Lee, J. A.; Carter, R. W.; Ding, J.

1999-01-01

This technical memorandum describes an investigation of using friction stir welding (FSW) process for joining a variety of aluminum metal matrix composites (MMC's) reinforced with discontinuous silicon-carbide (SiC) particulate and functional gradient materials. Preliminary results show that FSW is feasible to weld aluminum MMC to MMC or to aluminum-lithium 2195 if the SiC reinforcement is <25 percent by volume fraction. However, a softening in the heat-affected zone was observed and is known to be one of the major limiting factors for joint strength. The pin tool's material is made from a low-cost steel tool H-13 material, and the pin tool's wear was excessive such that the pin tool length has to be manually adjusted for every 5 ft of weldment. Initially, boron-carbide coating was developed for pin tools, but it did not show a significant improvement in wear resistance. Basically, FSW is applicable mainly for butt joining of flat plates. Therefore, FSW of cylindrical articles such as a flange to a duct with practical diameters ranging from 2-5 in. must be fully demonstrated and compared with other proven MMC joining techniques for cylindrical articles.

Role of Tool Shoulder End Features on Friction Stir Weld Characteristics of 6082 Aluminum Alloy

NASA Astrophysics Data System (ADS)

Mugada, Krishna Kishore; Adepu, Kumar

2018-03-01

Understanding the temperature generation around the tool shoulder contact is one of the important aspects of the friction stir welding process. In the present study, the effects of various tool shoulder end feature on the temperature and mechanical properties of the 6082 aluminum alloy were investigated. The experimental results show that the axial force during the welding is considerably reduced by using tools with shoulder end features. The detailed observation revealed that around the tool shoulder contact, the amount of heat generation is higher between trialing edge (TE) to retreating side-leading edge corner (RS-LE) counter clockwise direction and lower between RS-LE to TE clockwise direction. Out of the four shoulder end featured tools, the welds produced with ridges shoulder tool resulted in superior properties with significantly lower axial force (approximately 32%) compared to plane shoulder tool.

The Effects of Laser Peening and Shot Peening on Mechanical Properties in Friction Stir Welded 7075-T7351 Aluminum

NASA Technical Reports Server (NTRS)

Hatamleh, Omar

2006-01-01

Peening techniques like laser peening and shot peening were used to modify the surface of friction stir welded 7075-T7351 Aluminum Alloy specimens. The tensile coupons were machined such as the loading was applied in a direction perpendicular to the weld direction. The peening effects on the global and local mechanical properties through the different regions of the weld were characterized and assessed. The surface hardness levels resulting from various peening techniques were also investigated for both sides of the welds. Shot peening resulted in an increase to surface hardness levels, but no improvement was noticed on the mechanical properties. In contrast, mechanical properties were improved by laser peening when compared to the unpeened material.

Nd:YAG laser welding of coated sheet steel

DOE Office of Scientific and Technical Information (OSTI.GOV)

Graham, M.P.; Kerr, H.W.; Weckman, D.C.

1994-12-31

Coated sheet steels are used extensively in the automotive industry for the fabrication of automobile body components; however, their reduced weldability by the traditional welding processes has led to numerous studies into the use of alternate process such as laser welding. In this paper, we present a modified joint geometry which allows high quality lap welds of coated sheet steels to be made by laser welding processes. Hot-dipped galvanized sheet (16 gauge), with a 60 g/m zinc coating was used in this study. A groove was created in the top sheet of a specimen pair by pressing piano wires ofmore » various diameters into the sheet. The specimens were clamped together in a lag-joint configuration such that they were in contacted only along the grove projection. A parametric study was conducted using the variables of welding speed, laser mean power (685 W, 1000 W and 1350 W), and grove size. Weld quality and weld pool dimensions were assessed using metallurgical cross-sections and image analysis techniques. Acceptable quality seam welds were produced in the galvanized sheet steel with both grove sizes when using 1000 W and 1350 W laser mean powers and a range of welding speeds. Results of the shear-tensile tests showed that high loads to failure, with failure occurring in the parent material, were predominately found in welds produced at speeds over 1.2 m/min and when using the high mean laser powers: 1000 W and 1350 W. A modified lap joint geometry, in which a groove is pre-placed in the top sheet of the lap-joint configuration, has been developed which permits laser welding of coated sheet steels. Good quality seam welds have been produced in 16 gauge galvanized sheet steels at speeds up to 2.7 m/min using a 2 kW CW Nd:YAG laser operating at 1350 W laser mean power. Weld quality was not affected by changes in groove size.« less

Multihole Arc-Welding Orifice

NASA Technical Reports Server (NTRS)

Swaim, Benji D.

1989-01-01

Modified orifice for variable-polarity plasma-arc welding directs welding plume so it creates clean, even welds on both Inconel(R) and aluminum alloys. Includes eight holes to relieve back pressure in plasma. Quality of welds on ferrous and nonferrous alloys improved as result.

Effect of Heat Treatment on Mechanical Properties and Phase Composition of Magnesium-Aluminum Composite Prepared by Explosive Welding

NASA Astrophysics Data System (ADS)

Arisova, V. N.; Trykov, Yu. P.; Slautin, O. V.; Ponomareva, I. A.; Kondakov, A. E.

2015-09-01

Results are given for a study of the effect of heat treatment regimes on the nature of change in micromechanical properties and phase composition of magnesium-aluminum composite material AD1-MA2-1 prepared by explosive welding.

Fabrication of Aluminum Foam-Filled Thin-Wall Steel Tube by Friction Welding and Its Compression Properties

PubMed Central

Hangai, Yoshihiko; Saito, Masaki; Utsunomiya, Takao; Kitahara, Soichiro; Kuwazuru, Osamu; Yoshikawa, Nobuhiro

2014-01-01

Aluminum foam has received considerable attention in various fields and is expected to be used as an engineering material owing to its high energy absorption properties and light weight. To improve the mechanical properties of aluminum foam, combining it with dense tubes, such as aluminum foam-filled tubes, was considered necessary. In this study, an aluminum foam-filled steel tube, which consisted of ADC12 aluminum foam and a thin-wall steel tube, was successfully fabricated by friction welding. It was shown that a diffusion bonding layer with a thickness of approximately 10 μm was formed, indicating that strong bonding between the aluminum foam and the steel tube was realized. By the X-ray computed tomography observation of pore structures, the fabrication of an aluminum foam-filled tube with almost uniform pore structures over the entire specimen was confirmed. In addition, it was confirmed that the aluminum foam-filled steel tube exhibited mechanical properties superior to those of the ADC12 aluminum foam and steel tube. This is considered to be attributed to the combination of the aluminum foam and steel tube, which particularly prevents the brittle fracture and collapse of the ADC12 foam by the steel tube, along with the strong metal bonding between the aluminum foam and the steel tube. PMID:28788213

A Precise Visual Method for Narrow Butt Detection in Specular Reflection Workpiece Welding

PubMed Central

Zeng, Jinle; Chang, Baohua; Du, Dong; Hong, Yuxiang; Chang, Shuhe; Zou, Yirong

2016-01-01

During the complex path workpiece welding, it is important to keep the welding torch aligned with the groove center using a visual seam detection method, so that the deviation between the torch and the groove can be corrected automatically. However, when detecting the narrow butt of a specular reflection workpiece, the existing methods may fail because of the extremely small groove width and the poor imaging quality. This paper proposes a novel detection method to solve these issues. We design a uniform surface light source to get high signal-to-noise ratio images against the specular reflection effect, and a double-line laser light source is used to obtain the workpiece surface equation relative to the torch. Two light sources are switched on alternately and the camera is synchronized to capture images when each light is on; then the position and pose between the torch and the groove can be obtained nearly at the same time. Experimental results show that our method can detect the groove effectively and efficiently during the welding process. The image resolution is 12.5 μm and the processing time is less than 10 ms per frame. This indicates our method can be applied to real-time narrow butt detection during high-speed welding process. PMID:27649173

A Precise Visual Method for Narrow Butt Detection in Specular Reflection Workpiece Welding.

PubMed

Zeng, Jinle; Chang, Baohua; Du, Dong; Hong, Yuxiang; Chang, Shuhe; Zou, Yirong

2016-09-13

During the complex path workpiece welding, it is important to keep the welding torch aligned with the groove center using a visual seam detection method, so that the deviation between the torch and the groove can be corrected automatically. However, when detecting the narrow butt of a specular reflection workpiece, the existing methods may fail because of the extremely small groove width and the poor imaging quality. This paper proposes a novel detection method to solve these issues. We design a uniform surface light source to get high signal-to-noise ratio images against the specular reflection effect, and a double-line laser light source is used to obtain the workpiece surface equation relative to the torch. Two light sources are switched on alternately and the camera is synchronized to capture images when each light is on; then the position and pose between the torch and the groove can be obtained nearly at the same time. Experimental results show that our method can detect the groove effectively and efficiently during the welding process. The image resolution is 12.5 μm and the processing time is less than 10 ms per frame. This indicates our method can be applied to real-time narrow butt detection during high-speed welding process.

Alternating-Polarity Arc Welding

NASA Technical Reports Server (NTRS)

Schwinghamer, R. J.

1987-01-01

Brief reversing polarity of welding current greatly improves quality of welds. NASA technical memorandum recounts progress in art of variable-polarity plasma-arc (VPPA) welding, with emphasis on welding of aluminum-alloy tanks. VPPA welders offer important advantages over conventional single-polarity gas/tungsten arc welders.

Design for low-cost gas metal arc weld-based aluminum 3-D printing

NASA Astrophysics Data System (ADS)

Haselhuhn, Amberlee S.

Additive manufacturing, commonly known as 3-D printing, has the potential to change the state of manufacturing across the globe. Parts are made, or printed, layer by layer using only the materials required to form the part, resulting in much less waste than traditional manufacturing methods. Additive manufacturing has been implemented in a wide variety of industries including aerospace, medical, consumer products, and fashion, using metals, ceramics, polymers, composites, and even organic tissues. However, traditional 3-D printing technologies, particularly those used to print metals, can be prohibitively expensive for small enterprises and the average consumer. A low-cost open-source metal 3-D printer has been developed based upon gas metal arc weld (GMAW) technology. Using this technology, substrate release mechanisms have been developed, allowing the user to remove a printed metal part from a metal substrate by hand. The mechanical and microstructural properties of commercially available weld alloys were characterized and used to guide alloy development in 4000 series aluminum-silicon alloys. Wedge casting experiments were performed to screen magnesium, strontium, and titanium boride alloying additions in hypoeutectic aluminum-silicon alloys for their properties and the ease with which they could be printed. Finally, the top performing alloys, which were approximately 11.6% Si modified with strontium and titanium boride were cast, extruded, and drawn into wire. These wires were printed and the mechanical and microstructural properties were compared with those of commercially available alloys. This work resulted in an easier-to-print aluminum-silicon-strontium alloy that exhibited lower porosity, equivalent yield and tensile strengths, yet nearly twice the ductility compared to commercial alloys.

Microhardness Testing of Aluminum Alloy Welds

NASA Technical Reports Server (NTRS)

Bohanon, Catherine

2009-01-01

A weld is made when two pieces of metal are united or fused together using heat or pressure, and sometimes both. There are several different types of welds, each having their own unique properties and microstructure. Strength is a property normally used in deciding which kind of weld is suitable for a certain metal or joint. Depending on the weld process used and the heat required for that process, the weld and the heat-affected zone undergo microstructural changes resulting in stronger or weaker areas. The heat-affected zone (HAZ) is the region that has experienced enough heat to cause solid-state microstructural changes, but not enough to melt the material. This area is located between the parent material and the weld, with the grain structure growing as it progresses respectively. The optimal weld would have a short HAZ and a small fluctuation in strength from parent metal to weld. To determine the strength of the weld and decide whether it is suitable for the specific joint certain properties are looked at, among these are ultimate tensile strength, 0.2% offset yield strength and hardness. Ultimate tensile strength gives the maximum load the metal can stand while the offset yield strength gives the amount of stress the metal can take before it is 0.2% longer than it was originally. Both of these are good tests, but they both require breaking or deforming the sample in some way. Hardness testing, however, provides an objective evaluation of weld strengths, and also the difference or variation in strength across the weld and HAZ which is difficult to do with tensile testing. Hardness is the resistance to permanent or plastic deformation and can be taken at any desired point on the specimen. With hardness testing, it is possible to test from parent metal to weld and see the difference in strength as you progress from parent material to weld. Hardness around grain boundaries and flaws in the material will show how these affect the strength of the metal while still

Welding procedure specification. Supplement 1. Records of procedure qualification tests. Gas tungsten arc welding of aluminum alloys 3004, 5052, and 5X54

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wodtke, C.H.; Frizzell, D.R.; Plunkett, W.A.

1986-06-01

Procedure WPS-1002 is qualified under Section IX of the ASME Boiler and Pressure Vessel Code for gas tungsten arc welding of aluminum alloys 3004, 5052, 5154, and 5454 (P-22), in thickness range 0.062 to 0.5 inches; filler metal is ER4043 (F-23) for 3004, and ER5356 (F-22) for other alloys; shielding gas is argon.

The effect of laser surface melting on microstructure and corrosion behavior of friction stir welded aluminum alloy 2219

NASA Astrophysics Data System (ADS)

Ma, Shengchong; Zhao, Yong; Zou, Jiasheng; Yan, Keng; Liu, Chuan

2017-11-01

This study aimed to explore the electrochemical properties and microstructure of friction stir welds to understand the correlation between their properties and processing. Friction stir welding is a promising solid-state joining process for high-strength aluminum alloys (AA). Although friction stir welding (FSW) eliminates the problems of fusion welding due to the fact that it is performed below Tm, it causes severe plastic deformation in the material. Some AA welded by FSW exhibit relatively poor corrosion resistance. In this research, the corrosion resistance of such welds was enhanced through laser surface melting. A friction stir weld of AA 2219 was laser melted. The melt depth and microstructure were observed using optical and scanning electron microscopy. The melt zone exhibited epitaxially grown columnar grains. The redistribution of elemental composition was analyzed using energy-dispersive spectroscopy. The anticorrosion properties of both laser-melted and original welds were studied in aqueous 3.5% NaCl solution using cyclic potentiodynamic polarization. The results indicated a noticeable increase in the pitting corrosion resistance after the laser treatment on the surface. The repassivation potential was nobler than the corrosion potential after the laser treatment, confirming that the resistance to pitting growth improved.

Filler Wire Development for 2195 Aluminum-Lithium

NASA Technical Reports Server (NTRS)

Bjorkman, Gerry; Cho, Alex; Russell, Carolyn; Zimmerman, Frank

1998-01-01

The presentation outline summarizes activities supporting the development of filler wire for 215 aluminum-lithium. The specific objective of the research was to identify an Al-Cu based filler wire chemistry which reduces weld susceptibility in 2195 Aluminum-Lithium welds and repairs welds along with providing adequate mechanical properties. This report is in viewgraph form.

Welding rework data acquisition and automation

NASA Technical Reports Server (NTRS)

Romine, Peter L.

1996-01-01

Aluminum-Lithium is a modern material that NASA MSFC is evaluating as an option for the aluminum alloys and other aerospace metals presently in use. The importance of aluminum-lithium is in it's superior weight to strength characteristics. However, aluminum-lithium has produced many challenges in regards to manufacturing and maintenance. The solution to these problems are vital to the future uses of the shuttle for delivering larger payloads into earth orbit and are equally important to future commercial applications of aluminum-lithium. The Metals Processes Branch at MSFC is conducting extensive tests on aluminum-lithium which includes the collection of large amounts of data. This report discusses the automation and data acquisition for two processes: the initial weld and the repair. The new approach reduces the time required to collect the data, increases the accuracy of the data, and eliminates several types of human errors during data collection and entry. The same material properties that enhance the weight to strength characteristics of aluminum-lithium contribute to the problems with cracks occurring during welding, especially during the repair/rework process. The repairs are required to remove flaws or defects discovered in the initial weld, either discovered by x-ray, visual inspection, or some other type of nondestructive evaluation. It has been observed that cracks typically appear as a result of or beyond the second repair. MSFC scientists have determined that residual mechanical stress introduced by the welding process is a primary cause of the cracking. Two obvious solutions are to either prevent or minimize the stress introduced during the welding process, or remove or reduce the stress after the welding process and MSFC is investigating both of these.

Advanced Welding Applications

NASA Technical Reports Server (NTRS)

Ding, Robert J.

2010-01-01

Some of the applications of advanced welding techniques are shown in this poster presentation. Included are brief explanations of the use on the Ares I and Ares V launch vehicle and on the Space Shuttle Launch vehicle. Also included are microstructural views from four advanced welding techniques: Variable Polarity Plasma Arc (VPPA) weld (fusion), self-reacting friction stir welding (SR-FSW), conventional FSW, and Tube Socket Weld (TSW) on aluminum.

Effect of friction stir welding on microstructure and corrosion behavior of LF6 aluminum alloy

NASA Astrophysics Data System (ADS)

Ghauri, Faizan Ali; Farooq, A.; Ahmad, A.; Deen, K. M.

2017-03-01

The LF6 aluminum alloy plates were joined by friction stir welding method. The tool rotational (1180 rpm) and transverse speed (0.56 mm s-1) were kept constant during welding of 4 mm thick plates. The microstructural features, hardness and tensile properties of the welded samples were determined to evaluate the structural integrity in comparison with the base metal. The electrochemical behavior of base metal (BM), thermo-mechanically affected zone (TMAZ) and weld nugget zone (WNZ) was also investigated by potentiodynamic polarization and electrochemical impedance spectroscopy in 3.5% NaCl solution. The microstructural study revealed significant grain refinement and agglomeration of β (Mg2Al3) intermetallic precipitates in the WNZ. The relatively higher hardness and a decrease in the ductility (3%) also assured the formation of precipitates β precipitates in the WNZ welded samples. The fracture surface of welded sample also revealed the existence of β precipitates within the elongated dimples which may be considered as the crack initiation sites. The relatively lower corrosion rate (23.68 mpy) and higher charge transfer resistance (403 Ω cm2) of BM compared to WNZ could be associated with the galvanic dissolution of Al-matrix through competitive charge transfer and relaxation (adsorption/desorption of intermediate species) processes specifically at the vicinity of the β precipitates.

Shielded Metal Arc Pipe Welding. Teacher Edition. Second Edition.

ERIC Educational Resources Information Center

Fortney, Clarence; And Others

This second edition of the shielded metal arc pipe welding curriculum guide presents both basic and advanced pipe welding skills. All specifications for procedure and welder qualification are presented according to national standards. The standards also include the test position for both groove and fillet pipe welding. The guide contains three…

APPARATUS FOR ARC WELDING

DOEpatents

Lingafelter, J.W.

1960-04-01

An apparatus is described in which a welding arc created between an annular electrode and a workpiece moves under the influence of an electromagnetic field about the electrode in a closed or annular path. This mode of welding is specially suited to the enclosing of nuclear-fuel slugs in a protective casing. For example, a uranium slug is placed in an aluminum can, and an aluminum closure is welded to the open end of the can along a closed or annular path conforming to the periphery of the end closure.

Earth boring apparatus with multiple welds

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bolton, J.B.; Crews, S.T.

1981-06-16

A box tool joint member of generally tubular configuration is adapted for securement by welding to one end of a steel tube to form a drill pipe. The box tool joint member comprises a body having a cylindrical outer periphery, an internally threaded socket at one end of the body, and a weld neck of smaller outer diameter than the body adjacent to the other end of the body. A tapered transition piece connecting the neck with the adjacent end of the body provides an elevator shoulder. A correlative pin tool joint member is welded to the opposite end ofmore » the tube to complete the drill pipe. The box tool joint member has an annular band of hard facing over the outer periphery of the transition piece and extending down over the adjacent part of the weld neck and up around the adjacent part of the body. The hard facing is corrosion resistant and has a smooth finished surface. Underneath the hard facing and extending beyond both ends of the hard facing is an annular butter layer of non-hardenable steel. The tool joint member is hardened and tempered after the butter layer is welded into a body groove and before the hard facing is welded on .The butter layer is grooved before the hard facing is welded on.« less

Nugget Structure Evolution with Rotation Speed for High-Rotation-Speed Friction-Stir-Welded 6061 Aluminum Alloy

NASA Astrophysics Data System (ADS)

Zhang, H. J.; Wang, M.; Zhu, Z.; Zhang, X.; Yu, T.; Wu, Z. Q.

2018-03-01

High-rotation-speed friction stir welding (HRS-FSW) is a promising technique to reduce the welding loads during FSW and thus facilitates the application of FSW for in situ fabrication and repair. In this study, 6061 aluminum alloy was friction stir welded at high-rotation speeds ranging from 3000 to 7000 rpm at a fixed welding speed of 50 mm/min, and the effects of rotation speed on the nugget zone macro- and microstructures were investigated in detail in order to illuminate the process features. Temperature measurements during HRS-FSW indicated that the peak temperature did not increase consistently with rotation speed; instead, it dropped remarkably at 5000 rpm because of the lowering of material shear stress. The nugget size first increased with rotation speed until 5000 rpm and then decreased due to the change of the dominant tool/workpiece contact condition from sticking to sliding. At the rotation speed of 5000 rpm, where the weld material experienced weaker thermal effect and higher-strain-rate plastic deformation, the nugget exhibited relatively small grain size, large textural intensity, and high dislocation density. Consequently, the joint showed superior nugget hardness and simultaneously a slightly low tensile ductility.

Experimental Investigation on Friction Stir Welding of Cryorolled AA2219 Aluminum Alloy Joints

NASA Astrophysics Data System (ADS)

Babu, K. Kamal; Panneerselvam, K.; Sathiya, P.; Haq, A. Noorul; Sundarrajan, S.; Mastanaiah, P.; Murthy, C. V. Srinivasa

2017-07-01

In this paper, experimental investigation on cryorolled aluminum AA2219-T87 plate by using friction stir welding (FSW) process is carried out. AA2219-T87 plates with a size of 200×100×22.4 mm were rolled and reduced to 12.2mm thickness (more than 45% of reduction in total thickness of the base material) at cryogenic temperature (operating temperature range -90--30∘C). The cryorolled (CR) plates have reduced grain size, improved hardness and increased corrosion resistance property compared with the uncryorolled AA2219-T87 plates. FSW joints of cryorolled AA2219-T87 plates were prepared using cylindrical threaded FSW tool pin profile. Mechanical and metallurgical behaviors of friction stir welded joints were analyzed and the effects of the FSW process parameters are discussed in this paper. The variation of microhardness in the FSW joint regions were correlated with the microstructure of FSW joints. Cryorolled plate and FSW joints were tested for corrosion resistance using potentiodynamic polarization test. FSW joints shows better result during the corrosion resistance analysis compared to base AA2219-T87. The X-ray diffraction (XRD) test results showed that fine α-Al grains with eutectic phase (Al2Cu) were present in the weld nugget (WN). The large clusters of strengthening precipitates were reduced in size and merged with the weld nugget portion.

Friction Stir Welding of Steel Alloys

NASA Technical Reports Server (NTRS)

Ding, R. Jeffrey; Munafo, Paul M. (Technical Monitor)

2001-01-01

The friction stir welding process has been developed primarily for the welding of aluminum alloys. Other higher melting allows such, as steels are much more difficult to join. Special attention must be given to pin tool material selection and welding techniques. This paper addresses the joining of steels and other high melting point materials using the friction stir welding process. Pin tool material and welding parameters will be presented. Mechanical properties of weldments will also be presented. Significance: There are many applications for the friction stir welding process other than low melting aluminum alloys. The FSW process can be expanded for use with high melting alloys in the pressure vessel, railroad and ship building industries.

The Microstructure and Pitting Resistance of Weld Joints of 2205 Duplex Stainless Steel

NASA Astrophysics Data System (ADS)

Wu, Mingfang; Liu, Fei; Pu, Juan; Anderson, Neil E.; Li, Leijun; Liu, Dashuang

2017-11-01

2205 duplex stainless steel (DSS) was welded by submerged arc welding. The effects of both heat input and groove type on the ferrite/austenite ratio and elemental diffusion of weld joints were investigated. The relationships among welding joint preparation, ferrite/austenite ratio, elemental diffusion, and pitting corrosion resistance of weld joints were analyzed. When the Ni content of the weld wire deposit was at minimum 2-4% higher than that of 2205 DSS base metal, the desired ratio of ferrite/austenite and elemental partitioning between the austenite and ferrite phases were obtained. While the pitting sensitivity of weld metal was higher than that of base metal, the self-healing capability of the passive film of weld metal was better than that of the base metal when a single V-type groove was used. Furthermore, the heat input should be carefully controlled since pitting corrosion occurred readily in the coarse-grained heat-affected zone near the fusion line of welded joints.

Effects of stress concentration on the fatigue strength of 7003-T5 aluminum alloy butt joints with weld reinforcement

NASA Astrophysics Data System (ADS)

Zhu, Zongtao; Li, Yuanxing; Zhang, Mingyue; Hui, Chen

2015-03-01

7003-T5 Aluminum (Al) alloy plates with a thickness of 5 mm are welded by gas metal arc welding (GMAW) method in this work. In order to investigate the influence of stress concentration introduced by weld reinforcement on fatigue strength, the stress concentration factor of the butt joint is calculated. Microscopic and X-ray techniques were utilized to make sure there are no weld defects with large size in butt weld, which can induce extra stress concentration. The cyclic stress - number of cycles to failure (S-N) curves of the joints with and without the welder were obtained by fatigue testing, and the results show that the fatigue strength of 7003-T5 Al alloy butt joints with the weld reinforcement is 50 MPa, which is only 45% of the joints without the weld reinforcement. Fracture surface observation indicated that the fatigue source and propagation are dissimilar for the specimens with and without the welder due to the stress concentration at the weld root. The stress concentration with a factor of 1.7 has great effect on the fatigue strength, but little influence on the tensile strength.

Laser Spot Welding of Copper-aluminum Joints Using a Pulsed Dual Wavelength Laser at 532 and 1064 nm

NASA Astrophysics Data System (ADS)

Stritt, Peter; Hagenlocher, Christian; Kizler, Christine; Weber, Rudolf; Rüttimann, Christoph; Graf, Thomas

A modulated pulsed laser source emitting green and infrared laser light is used to join the dissimilar metals copper and aluminum. The resultant dynamic welding process is analyzed using the back reflected laser light and high speed video observations of the interaction zone. Different pulse shapes are applied to influence the melt pool dynamics and thereby the forming grain structure and intermetallic phases. The results of high-speed images and back-reflections prove that a modulation of the pulse shape is transferred to oscillations of the melt pool at the applied frequency. The outcome of the melt pool oscillation is shown by the metallurgically prepared cross-section, which indicates different solidification lines and grain shapes. An energy-dispersivex-ray analysis shows the mixture and the resultant distribution of the two metals, copper and aluminum, within the spot weld. It can be seen that the mixture is homogenized the observed melt pool oscillations.

Looking north at uing press of the submerged arc weld ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Looking north at u-ing press of the submerged arc weld (saw) line of the main pipe mill building, bay 7. - U.S. Steel National Tube Works, Main Pipe Mill Building, Along Monongahela River, McKeesport, Allegheny County, PA

Effects of Fusion Tack Welds on Self-Reacting Friction Stir Welds

NASA Technical Reports Server (NTRS)

Nunes, A. C., Jr.; Pendleton, M. L.; Brooke, S. A.; Russell, C. K.

2012-01-01

In order to know whether fusion tack welds would affect the strength of self-reacting friction stir seam welds in 2195-T87 aluminum alloy, the fracture stresses of 144 tensile test coupons cut from 24 welded panels containing segments of friction stir welds were measured. Each of the panels was welded under unique processing conditions. A measure of the effect of the tack welds for each panel was devised. An analysis of the measures of the tack weld effect supported the hypothesis that fusion tack welds do not affect the strength of self-reacting friction stir welds to a 5% level of confidence.

Hybrid/Tandem Laser-Arc Welding of Thick Low Carbon Martensitic Stainless Steel Plates =

NASA Astrophysics Data System (ADS)

Mirakhorli, Fatemeh

High efficiency and long-term life of hydraulic turbines and their assemblies are of utmost importance for the hydropower industry. Usually, hydroelectric turbine components are made of thick-walled low carbon martensitic stainless steels. The assembly of large hydroelectric turbine components has been a great challenge. The use of conventional welding processes involves typical large groove design and multi-pass welding to fill the groove which exposes the weld to a high heat input creating relatively large fusion zone and heat affected zone. The newly-developed hybrid/tandem laser-arc welding technique is believed to offer a highly competitive solution to improve the overall hydro-turbine performance by combining the high energy density and fast welding speed of the laser welding technology with the good gap bridging and feeding ability of the gas metal arc welding process to increase the productivity and reduce the consumable material. The main objective of this research work is to understand different challenges appearing during hybrid laser-arc welding (HLAW) of thick gauge assemblies of low carbon 13%Cr- 4%Ni martensitic stainless steel and find a practical solution by adapting and optimizing this relatively new welding process in order to reduce the number of welding passes necessary to fill the groove gap. The joint integrity was evaluated in terms of microstructure, defects and mechanical properties in both as-welded and post-welded conditions. A special focus was given to the hybrid and tandem laser-arc welding technique for the root pass. Based on the thickness of the low carbon martensitic stainless steel plates, this work is mainly focused on the following two tasks: • Single pass hybrid laser-arc welding of 10-mm thick low carbon martensitic stainless steel. • Multi-pass hybrid/tandem laser-arc welding of 25-mm thick martensitic stainless steel.

The effect of postprocessing on tensile property and microstructure evolution of friction stir welding aluminum alloy joint

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hu, Z.L., E-mail: zhilihuhit@163.com; State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin 150001; State Key Laboratory of Materials Processing and Die & Mould Technology, Huazhong University of Science and Technology

Friction stir welding is an efficient manufacturing method for joining aluminum alloy and can dramatically reduce grain size conferring excellent plastic deformation properties. Consequently, friction stir welding is used to manufacture tailor welded blanks to optimize weight or performance in the final component. In the study, the microstructural evolution and mechanical properties of friction stir welding joint during plastic forming and subsequent heat treatment were investigated. The microstructural characteristics of the friction stir welding joints were studied by Electron Backscattered Diffraction and Transmission Electron Microscopy. The mechanical properties were evaluated by tensile and microhardness tests. It is found that themore » tensile and yield strengths of friction stir welding joints are significantly improved after severe plastic deformation due to the grain refinement. Following heat treatment, the strength of the friction stir welding joints significantly decrease due to the obvious abnormal grain growth. Careful attention must be given to the processing route of any friction stir welding joint intended for plastic forming, especially the annealing between forming passes. Severe plastic deforming of the friction stir welding joint leads to a high level of stored energy/dislocation density, which causes the abnormal grain growth during subsequent heat treatment, and consequently reduce the mechanical properties of the friction stir welding joint. - Highlights: • Great changes are observed in the microstructure of FSW joint after postprocessing. • Postprocessing shows great effect on the microstructure stability of FSW joint. • The weld shows more significant decrease in strength than the BM due to the AGG. • Attention must be given to the processing route of FSW joint for plastic forming.« less

Saturn S-2 production operations techniques: Production welding. Volume 1: Bulkhead welding

NASA Technical Reports Server (NTRS)

Abel, O. G.

1970-01-01

The complex Saturn S-2 welding processes and procedures required considerable development and refinement to establish a production capability that could consistently produce aluminum alloy welds within specified requirements. The special processes and techniques are defined that were established for the welding of gore-to-gore and manhole- or closeout-to-gore.

Surface preparation effects on GTA weld shape in JBK-75 stainless steel

DOE Office of Scientific and Technical Information (OSTI.GOV)

Campbell, R.D.; Robertson, A.M.; Heiple, C.R.

1993-02-01

The results of a study are reported here on the effects of surface preparation on the shape of autogenous gas tungsten arc (GTA) welds in JBK-75, an austenitic precipitation hardenable stainless steel similar to A286. Minor changes in surface preparation produced substantial changes in the fusion zone shape and welding behavior of this alloy. Increased and more consistent depth of fusion (higher d/w ratios) along with improved arc stability and less arc wander resulted from wire brushing and other abrasive surface preparations, although chemical and machining methods did not produce any increase in depth of fusion. Abrasive treatments roughen themore » surface, increase the surface area, increase the surface oxide thickness, and entrap oxide. The increased weld d/w ratio is attributed to oxygen added to the weld pool from the surface oxide on the base metal. The added oxygen alters the surface-tension-driven fluid flow pattern in the weld pool. Increased depth of fusion in wire-fed U-groove weld joints also resulted when welding wire with a greater surface oxide thickness was used. Increasing the amount of wire brushing produced even deeper welds. However, a maximum in depth of fusion was observed with further wire brushing, beyond which weld fusion depth decreased.« less

Advanced Process Possibilities in Friction Crush Welding of Aluminum, Steel, and Copper by Using an Additional Wire

NASA Astrophysics Data System (ADS)

Besler, Florian A.; Grant, Richard J.; Schindele, Paul; Stegmüller, Michael J. R.

2017-12-01

Joining sheet metal can be problematic using traditional friction welding techniques. Friction crush welding (FCW) offers a high speed process which requires a simple edge preparation and can be applied to out-of-plane geometries. In this work, an implementation of FCW was employed using an additional wire to weld sheets of EN AW5754 H22, DC01, and Cu-DHP. The joint is formed by bringing together two sheet metal parts, introducing a wire into the weld zone and employing a rotating disk which is subject to an external force. The requirements of the welding preparation and the fundamental process variables are shown. Thermal measurements were taken which give evidence about the maximum temperature in the welding center and the temperature in the periphery of the sheet metals being joined. The high welding speed along with a relatively low heat input results in a minimal distortion of the sheet metal and marginal metallurgical changes in the parent material. In the steel specimens, this FCW implementation produces a fine grain microstructure, enhancing mechanical properties in the region of the weld. Aluminum and copper produced mean bond strengths of 77 and 69 pct to that of the parent material, respectively, whilst the steel demonstrated a strength of 98 pct. Using a wire offers the opportunity to use a higher-alloyed additional material and to precisely adjust the additional material volume appropriate for a given material alignment and thickness.

Taguchi Optimization of Pulsed Current GTA Welding Parameters for Improved Corrosion Resistance of 5083 Aluminum Welds

NASA Astrophysics Data System (ADS)

Rastkerdar, E.; Shamanian, M.; Saatchi, A.

2013-04-01

In this study, the Taguchi method was used as a design of experiment (DOE) technique to optimize the pulsed current gas tungsten arc welding (GTAW) parameters for improved pitting corrosion resistance of AA5083-H18 aluminum alloy welds. A L9 (34) orthogonal array of the Taguchi design was used, which involves nine experiments for four parameters: peak current ( P), base current ( B), percent pulse-on time ( T), and pulse frequency ( F) with three levels was used. Pitting corrosion resistance in 3.5 wt.% NaCl solution was evaluated by anodic polarization tests at room temperature and calculating the width of the passive region (∆ E pit). Analysis of variance (ANOVA) was performed on the measured data and S/ N (signal to noise) ratios. The "bigger is better" was selected as the quality characteristic (QC). The optimum conditions were found as 170 A, 85 A, 40%, and 6 Hz for P, B, T, and F factors, respectively. The study showed that the percent pulse-on time has the highest influence on the pitting corrosion resistance (50.48%) followed by pulse frequency (28.62%), peak current (11.05%) and base current (9.86%). The range of optimum ∆ E pit at optimum conditions with a confidence level of 90% was predicted to be between 174.81 and 177.74 mVSCE. Under optimum conditions, the confirmation test was carried out, and the experimental value of ∆ E pit of 176 mVSCE was in agreement with the predicted value from the Taguchi model. In this regard, the model can be effectively used to predict the ∆ E pit of pulsed current gas tungsten arc welded joints.

Homogeneity of Mechanical Properties of Underwater Friction Stir Welded 2219-T6 Aluminum Alloy

NASA Astrophysics Data System (ADS)

Liu, H. J.; Zhang, H. J.; Yu, L.

2011-11-01

Underwater friction stir welding (FSW) has been demonstrated to be available for the improvement in tensile strength of normal FSW joints. In order to illuminate the intrinsic reason for strength improvement through underwater FSW, a 2219 aluminum alloy was underwater friction stir welded and the homogeneity of mechanical properties of the joint was investigated by dividing the joint into three layers. The results indicate that the tensile strength of the three layers of the joint is all improved by underwater FSW, furthermore, the middle and lower layers have larger extent of strength improvement than the upper layer, leading to an increase in the homogeneity of mechanical properties of the joint. The minimum hardness value of each layer, especially the middle and lower layers, is improved under the integral water cooling effect, which is the intrinsic reason for the strength improvement of underwater joint.

Analysis and Prediction of the Billet Butt and Transverse Weld in the Continuous Extrusion Process of a Hollow Aluminum Profile

NASA Astrophysics Data System (ADS)

Lou, Shumei; Wang, Yongxiao; Liu, Chuanxi; Lu, Shuai; Liu, Sujun; Su, Chunjian

2017-08-01

In continuous extrusions of aluminum profiles, the thickness of the billet butt and the length of the discarded extrudate containing the transverse weld play key roles in reducing material loss and improving product quality. The formation and final distribution of the billet butt and transverse weld depend entirely on the flow behavior of the billet skin material. This study examined the flow behavior of the billet skin material as well as the formation and evolution of the billet butt and the transverse weld in detail through numerical simulation and a series of experiments. In practical extrusions, even if the billet skin is removed by lathe turning shortly before extrusion, billet skin impurities are still distributed around the transverse weld and in the billet butt. The thickness of the scrap billet butt and the length of the discarded extrudate containing the transverse weld can be exactly predicted via simulation.

Special Features of the Structure of Laser-Welded Joints of Dissimilar Alloys Based on Titanium and Aluminum

NASA Astrophysics Data System (ADS)

Nikulina, A. A.; Smirnov, A. I.; Turichin, G. A.; Klimova-Korsmik, O. G.; Babkin, K. D.

2017-11-01

The structure of laser-welded joints of parts having different thicknesses fabricated from alloys based on aluminum and titanium has been studied. Results of transmission and scanning electron microscopy measurements and x-ray diffraction analysis show that the diffusion interaction of microvolumes of two alloys in the weld leads to the formation of two interlayers: (i) a continuous intermetallic TiAl layer with thickness below 1 μm adjacent to the titanium alloy and (ii) a layer consisting of TiAl3 intermetallic dendrites with thickness of 2 - 6 μm adjacent to the TiAl layer. The average microhardness of the intermetallic layer is about 490 HV.

Comparison of the Effects of Tool Geometry for Friction Stir Welding Thin Sheet Aluminum Alloys for Aerospace Applications

NASA Technical Reports Server (NTRS)

Merry, Josh; Takeshita, Jennifer; Tweedy, Bryan; Burford, Dwight

2006-01-01

In this presentation, the results of a recent study on the effect of pin tool design for friction stir welding thin sheets (0.040") of aluminum alloys 2024 and 7075 are provided. The objective of this study was to investigate and document the effect of tool shoulder and pin diameter, as well as the presence of pin flutes, on the resultant microstructure and mechanical properties at both room temperature and cryogenic temperature. Specifically, the comparison between three tools will include: FSW process load analysis (tool forces required to fabricate the welds), Static Mechanical Properties (ultimate tensile strength, yield strength, and elongation), and Process window documenting the range of parameters that can be used with the three pin tools investigated. All samples were naturally aged for a period greater than 10 days. Prior research has shown 7075 may require post weld heat treatment. Therefore, an additional pair of room temperature and cryogenic temperature samples was post-weld aged to the 7075-T7 condition prior to mechanical testing.

Influence of friction stir welding parameters on titanium-aluminum heterogeneous lap joining configuration

NASA Astrophysics Data System (ADS)

Picot, Florent; Gueydan, Antoine; Hug, Éric

2017-10-01

Lap joining configuration for Friction Stir Welding process is a methodology mostly dedicated to heterogeneous bonding. This welding technology was applied to join pure titanium with pure aluminum by varying the rotation speed and the movement speed of the tool. Regardless of the process parameters, it was found that the maximum strength of the junction remains almost constant. Microstructural observations by means of Scanning Electron Microscopy and Energy Dispersive Spectrometry analysis enable to describe the interfacial join and reveal asymmetric Cold Lap Defects on the sides of the junction. Chemical analysis shows the presence of one exclusive intermetallic compound through the interface identified as TiAl3. This compound is responsible of the crack spreading of the junction during the mechanical loading. The original version of this article supplied to AIP Publishing contained an accidental inversion of the authors, names. An updated version of this article, with the authors names formatted correctly was published on 20 October 2017.

Microstructure and Fatigue Properties of Ultrasonic Spot Welded Joints of Aluminum 5754 Alloy

NASA Astrophysics Data System (ADS)

Mirza, F. A.; Macwan, A.; Bhole, S. D.; Chen, D. L.

2016-05-01

The purpose of this investigation was to evaluate the microstructural change, lap shear tensile load, and fatigue resistance of ultrasonic spot welded joints of aluminum 5754 alloy for automotive applications. A unique "necklace"-type structure with very fine equiaxed grains was observed to form along the weld line due to the mechanical interlocking coupled with the occurrence of dynamic recrystallization. The maximum lap shear tensile strength of 85 MPa and the fatigue limit of about 0.5 kN (at 1 × 107 cycles) were achieved. The tensile fracture occurred at the Al/Al interface in the case of lower energy inputs, and at the edge of nugget zone in the case of higher energy inputs. The maximum cyclic stress for the transition of fatigue fracture mode from the transverse through-thickness crack growth to the interfacial failure increased with increasing energy input. Fatigue crack propagation was mainly characterized by the formation of fatigue striations, which usually appeared perpendicular to the fatigue crack propagation.

The Effectiveness of Surface Coatings on Preventing Interfacial Reaction During Ultrasonic Welding of Aluminum to Magnesium

NASA Astrophysics Data System (ADS)

Panteli, Alexandria; Robson, Joseph D.; Chen, Ying-Chun; Prangnell, Philip B.

2013-12-01

High power ultrasonic spot welding (USW) is a solid-state joining process that is advantageous for welding difficult dissimilar material couples, like magnesium to aluminum. USW is also a useful technique for testing methods of controlling interfacial reaction in welding as the interface is not greatly displaced by the process. However, the high strain rate deformation in USW has been found to accelerate intermetallic compound (IMC) formation and a thick Al12Mg17 and Al3Mg2 reaction layer forms after relatively short welding times. In this work, we have investigated the potential of two approaches for reducing the IMC reaction rate in dissimilar Al-Mg ultrasonic welds, both involving coatings on the Mg sheet surface to (i) separate the join line from the weld interface, using a 100- μm-thick Al cold spray coating, and (ii) provide a diffusion barrier layer, using a thin manganese physical vapor deposition (PVD) coating. Both methods were found to reduce the level of reaction and increase the failure energy of the welds, but their effectiveness was limited due to issues with coating attachment and survivability during the welding cycle. The effect of the coatings on the joint's interface microstructure, and the fracture behavior have been investigated in detail. Kinetic modeling has been used to show that the benefit of the cold spray coating can be attributed to the reaction rate reverting to that expected under static conditions. This reduces the IMC growth rate by over 50 pct because at the weld line, the high strain rate dynamic deformation in USW normally enhances diffusion through the IMC layer. In comparison, the thin PVD barrier coating was found to rapidly break up early in USW and become dispersed throughout the deformation layer reducing its effectiveness.

Friction welding.

NASA Technical Reports Server (NTRS)

Moore, T. J.

1972-01-01

Results of an exploratory study of the structure and properties of friction welds in Udimet 700 (U-700) and TD-nickel (TD-Ni) bar materials, as well as dissimilar U-700/TD-Ni friction welds. Butt welds were prepared by friction welding 12.7-mm-diam U-700 bars and TD-Ni bars. Specimens for elevated temperature tensile and stress rupture testing were machined after a postweld heat treatment. Friction welding of U-700 shows great potential because the welds were found to be as strong as the parent metal in stress rupture and tensile tests at 760 and 980 C. In addition, the weld line was not detectable by metallographic examination after postheating. Friction welds in TD-Ni or between U-700 and TD-Ni were extremely weak at elevated temperatures. The TD-Ni friction welds could support only 9% as much stress as the base metal for 10-hour stress rupture life at 1090 C. The U-700/TD-Ni weld could sustain only 15% as much stress as the TD-Ni parent metal for a 10-hour stress rupture life at 930 C. Thus friction welding is not a suitable joining method for obtaining high-strength TD-Ni or U-700/TD-Ni weldments.

Local-scale stratigraphy of grooved terrain on Ganymede

NASA Technical Reports Server (NTRS)

Murchie, Scott L.; Head, James W.; Helfenstein, Paul; Plescia, Jeffrey B.

1987-01-01

The surface of the Jovian satellite, Ganymede, is divided into two main units, dark terrain cut by arcuate and subradial furrows, and light terrain consisting largely of areas with pervasive U-shaped grooves. The grooved terrain may be subdivided on the basis of pervasive morphology of groove domains into four terrain types: (1) elongate bands of parallel grooves (groove lanes); (2) polygonal domains of parallel grooves (grooved polygons); (3) polygonal domains of two orthogonal groove sets (reticulate terrain); and (4) polygons having two to several complexly cross-cutting groove sets (complex grooved terrain). Reticulate terrain is frequently dark and not extensively resurfaced, and grades to a more hummocky terrain type. The other three grooved terrain types have almost universally been resurfaced by light material during their emplacement. The sequence of events during grooved terrain emplacement has been investigated. An attempt is made to integrate observed geologic and tectonic patterns to better constrain the relative ages and styles of emplacement of grooved terrain types. A revised model of grooved terrain emplacement is proposed and is tested using detailed geologic mapping and measurement of crater density.

Silver-free solar cell interconnection by laser spot welding of thin aluminum layers: analysis of process limits for ns- and μs-lasers

NASA Astrophysics Data System (ADS)

Schulte-Huxel, H.; Blankemeyer, S.; Kajari-Schröder, S.; Brendel, R.

2014-03-01

We investigate a laser welding process for contacting aluminum metallized crystalline silicon solar cells to a 10-μm-thick aluminum layers on a glass substrate. The reduction of the solar cell metallization thickness is analyzed with respect to laser induced damage using SiNx passivated silicon wafers. Additionally, we measure the mechanical stress of the laser welds by perpendicular tear-off as well as the electrical contact resistance. We apply two types of laser processes; one uses one to eight 20-ns-laser pulses at 355 nm with fluences between 12 and 40 J/cm2 and the other single 1.2-μs-laser pulses at 1064 nm with 33 to 73 J/cm2. Ns laser pulses can contact down to 1-μm-thick aluminum layers on silicon without inducing laser damage to the silicon and lead to sufficient strong mechanical contact. In case of μs laser pulses the limiting thickness is 2 μm.

Addressing the Limit of Detectability of Residual Oxide Discontinuities in Friction Stir Butt Welds of Aluminum using Phased Array Ultrasound

NASA Technical Reports Server (NTRS)

Johnston, P. H.

2008-01-01

This activity seeks to estimate a theoretical upper bound of detectability for a layer of oxide embedded in a friction stir weld in aluminum. The oxide is theoretically modeled as an ideal planar layer of aluminum oxide, oriented normal to an interrogating ultrasound beam. Experimentally-measured grain scattering level is used to represent the practical noise floor. Echoes from naturally-occurring oxides will necessarily fall below this theoretical limit, and must be above the measurement noise to be potentially detectable.

Evolution of the Structure of Local Regions of Fused Metal in Explosion-Welded Nickel-Aluminum Composites Under Heat Treatment

NASA Astrophysics Data System (ADS)

Shmorgun, V. G.; Bogdanov, A. I.; Gurevich, L. M.

2016-03-01

The methods of electron, optical, and atomic force microscopy are used to study the structure, morphology and phase composition of local regions of fused metal in an explosion-welded nickel-aluminum composite. It is shown that the diffusion zone formed due to the heat treatment repeats the contour of the fuse in the first stage and then "absorbs" it upon duration of the hold thus leveling the phase composition. ANi2Al3 Aluminide layer forms on the side of nickel and a NiAl3 layer forms on the side of aluminum.

Interfacial Microstructure and Mechanical Properties of Friction Stir Welded Joints of Commercially Pure Aluminum and 304 Stainless Steel

NASA Astrophysics Data System (ADS)

Murugan, Balamagendiravarman; Thirunavukarasu, Gopinath; Kundu, Sukumar; Kailas, Satish V.; Chatterjee, Subrata

2018-05-01

In the present investigation, friction stir welding of commercially pure aluminum and 304 stainless steel was carried out at varying tool rotational speeds from 200 to 1000 rpm in steps of 200 rpm using 60 mm/min traverse speed at 2 (degree) tool tilt angle. Microstructural characterization of the interfacial zone was carried out using optical microscope and scanning electron microscope. Energy-dispersive spectroscopy indicated the presence of FeAl3 intermetallic phase. Thickness of the intermetallic layer increased with the increase in tool rotational speed. X-ray diffraction studies indicated the formation of intermetallic phases like FeAl2, Fe4Al13, Fe2Al5, and FeAl3. A maximum tensile strength of 90% that of aluminum along with 4.5% elongation was achieved with the welded sample at tool rotational speed of 400 rpm. The stir zone showed higher hardness as compared to base metals, heat affected zone, and thermo-mechanically affected zone due to the presence of intermetallics. The maximum hardness value at the stir zone was achieved at 1000 rpm tool rotational speed.

Influence of shielding gas on the mechanical and metallurgical properties of DP-GMA-welded 5083-H321 aluminum alloy

NASA Astrophysics Data System (ADS)

Koushki, Amin Reza; Goodarzi, Massoud; Paidar, Moslem

2016-12-01

In the present research, 6-mm-thick 5083-H321 aluminum alloy was joined by the double-pulsed gas metal arc welding (DP-GMAW) process. The objective was to investigate the influence of the shielding gas composition on the microstructure and properties of GMA welds. A macrostructural study indicated that the addition of nitrogen and oxygen to the argon shielding gas resulted in better weld penetration. Furthermore, the tensile strength and bending strength of the welds were improved when oxygen and nitrogen (at concentrations as high as approximately 0.1vol%) were added to the shielding gas; however, these properties were adversely affected when the oxygen and nitrogen contents were increased further. This behavior was attributed to the formation of excessive brown and black oxide films on the bead surface, the formation of intermetallic compounds in the weld metal, and the formation of thicker oxide layers on the bead surface with increasing nitrogen and oxygen contents in the argon-based shielding gas. Analysis by energy-dispersive X-ray spectroscopy revealed that most of these compounds are nitrides or oxides.

Wide Panel Testing Technique for Evaluating Repair Weld Strengths

NASA Technical Reports Server (NTRS)

Rogers, Patrick R.; Bynum, Julian E.; Shah, Sandeep R.

1998-01-01

This paper describes a new tensile testing technique for evaluating the overall effect of a repair weld on the strength of a welded joint. Previously, repair weld strengths have been evaluated using one-inch width tensile specimens, but this technique does not capture all of the effects that result from a repair. The new technique involves testing of "wide panel" tensile specimens which contain the full length of a repair weld within a longer initial weld, allowing the specimen to capture the combined effects of residual stresses, local strength degradation, and load redistribution around a repair. The development of strains in the repair area of standard aluminum alloy specimens and new high-performance aluminum-lithium alloy specimens was observed and evaluated using photoelastic material. The results of this evaluation show an increased sensitivity to repair welding residual stresses in the aluminum-lithium alloy specimens.

Role of the micro/macro structure of welds in crack nucleation and propagation in aerospace aluminum-lithium alloy

NASA Technical Reports Server (NTRS)

Talia, George E.

1996-01-01

Al-Li alloys offer the benefits of increased strength, elastic modulus and lower densities as compared to conventional aluminum alloys. Martin Marietta Laboratories has developed an Al-Li alloy designated 2195 which is designated for use in the cryogenic tanks of the space shuttle. The Variable Polarity Plasma Arc (VPPA) welding process is currently being used to produce these welds [1]. VPPA welding utilizes high temperature ionized gas (plasma) to transfer heat to the workpiece. An inert gas, such as Helium, is used to shield the active welding zone to prevent contamination of the molten base metal with surrounding reactive atmospheric gases. [1] In the Space Shuttle application, two passes of the arc are used to complete a butt-type weld. The pressure of the plasma stream is increased during the first pass to force the arc entirely through the material, a practice commonly referred to as keyholing. Molten metal forms on either side of the arc and surface tension draws this liquid together as the arc passes. 2319 Al alloy filler material may also be fed into the weld zone during this pass. During the second pass, the plasma stream pressure is reduced such that only partial penetration of the base material is obtained. Al 2319 filler material is added during this pass to yield a uniform, fully filled welded joint. This additional pass also acts to alter the grain structure of the weld zone to yield a higher strength joint.

Picosecond laser welding of similar and dissimilar materials.

PubMed

Carter, Richard M; Chen, Jianyong; Shephard, Jonathan D; Thomson, Robert R; Hand, Duncan P

2014-07-01

We report picosecond laser welding of similar and dissimilar materials based on plasma formation induced by a tightly focused beam from a 1030 nm, 10 ps, 400 kHz laser system. Specifically, we demonstrate the welding of fused silica, borosilicate, and sapphire to a range of materials including borosilicate, fused silica, silicon, copper, aluminum, and stainless steel. Dissimilar material welding of glass to aluminum and stainless steel has not been previously reported. Analysis of the borosilicate-to-borosilicate weld strength compares well to those obtained using similar welding systems based on femtosecond lasers. There is, however, a strong requirement to prepare surfaces to a high (10-60 nm Ra) flatness to ensure a successful weld.

Effect of dual laser beam on dissimilar welding-brazing of aluminum to galvanized steel

NASA Astrophysics Data System (ADS)

Mohammadpour, Masoud; Yazdian, Nima; Yang, Guang; Wang, Hui-Ping; Carlson, Blair; Kovacevic, Radovan

2018-01-01

In this investigation, the joining of two types of galvanized steel and Al6022 aluminum alloy in a coach peel configuration was carried out using a laser welding-brazing process in dual-beam mode. The feasibility of this method to obtain a sound and uniform brazed bead with high surface quality at a high welding speed was investigated by employing AlSi12 as a consumable material. The effects of alloying elements on the thickness of intermetallic compound (IMC) produced at the interface of steel and aluminum, surface roughness, edge straightness and the tensile strength of the resultant joint were studied. The comprehensive study was conducted on the microstructure of joints by means of a scanning electron microscopy and EDS. Results showed that a dual-beam laser shape and high scanning speed could control the thickness of IMC as thin as 3 μm and alter the failure location from the steel-brazed interface toward the Al-brazed interface. The numerical simulation of thermal regime was conducted by the Finite Element Method (FEM), and simulation results were validated through comparative experimental data. FEM thermal modeling evidenced that the peak temperatures at the Al-steel interface were around the critical temperature range of 700-900 °C that is required for the highest growth rate of IMC. However, the time duration that the molten pool was placed inside this temperature range was less than 1 s, and this duration was too short for diffusion-control based IMC growth.

Microstructure Evolution and Mechanical Properties of High-Speed Friction Stir Welded Aluminum Alloy Thin Plate Joints

NASA Astrophysics Data System (ADS)

Liu, Fenjun; Fu, Li; Chen, Haiyan

2018-06-01

Sound friction stir welded (FSW) joints of 6061-T6 aluminum alloy sheets with an 0.8 mm thickness were obtained at conventional speed (2000 rpm, 300 mm/min) and high speed (11,000 rpm, 1500 mm/min). The recrystallization mechanism, precipitate evolution, mechanical properties and fracture behavior were investigated in detail. Microstructure analyses revealed that the grain structure evolution in the nugget zone (NZ) was dominated by continuous dynamic recrystallization. In the process of FSW, high speed facilitates the formation of finer equiaxed recrystallized grains, higher density of dislocations and substructures, and a larger number of precipitates in the NZ compared to the conventional speed, which further significantly improves the hardness and tensile strength of the joints. The maximum tensile strength was obtained with 292.6 MPa, 83.2% for the 6061-T6 aluminum alloy and 122.6% for the conventional-speed FSW joints. This work provides an effective method for preparing FSW aluminum alloy thin plate joints with excellent mechanical properties.

Effects of Variables in Welding Technique on the Strength of Direct-Current Metal-Arc-Welded Joints in Aircraft Steel. 1 - Static Tension and Bending Fatigue Tests of Joints in SAE 4130 Steel Sheet

DTIC Science & Technology

1947-07-01

specimen melting through. Neither metallic nor refrac- tory strips were used to hack up the weld groove. The single-head weld was used, rather than a...fr>J NACA TN No. 1361 co m > m d O •P CM CO s o In «3 § • rH 8 g 8 "S| « a> rH ^ j5 r— "-1 rH +» » • • • rH d VX> vo o in i-i J- K...01 5 o d 4> 01 4> J5 oi g 4> 4> 4» C -Ö P Q, O 5- 5 o g. o 8> II 2 - u d •do *» a, d 2

Reinforcement with alumina particles at the interface region of AA6101-T6 and AA1350 alloys during friction stir welding

NASA Astrophysics Data System (ADS)

Ashok Kumar, R.; Thansekhar, M. R.

2018-04-01

This paper deals the combinational effect of friction stir welding and friction stir processing on dissimilar AA6101-T6 and AA1350 aluminium alloys. For that, alumina particles are reinforced at interface region of AA6101-T6 and AA1350 aluminium alloys. Friction Stir Welding and Friction Stir Processing are done simultaneously for various sizes of groove. To analyze the welding quality and surface modifications, mechanical, wear and microstructural tests are carried out. Among these, smallest groove of 0.5 mm width and 1 mm depth reveals highest tensile and bending strengths and largest groove of 2 mm width and 3 mm depth gives maximum hardness and wear resistance. Taguchi technique shows that groove width is most influencing parameter. Developed second order models with interaction predict the responses with minimum error.

Numerical simulation of spatter formation during fiber laser welding of 5083 aluminum alloy at full penetration condition

NASA Astrophysics Data System (ADS)

Wu, Dongsheng; Hua, Xueming; Huang, Lijin; Zhao, Jiang

2018-03-01

The droplet escape condition in laser welding is established in this paper. A three-dimensional numerical model is developed to study the weld pool convection and spatter formation at full penetration during the fiber laser welding of 5083 aluminum alloy. It is found that when laser power is 9 kW, the bottom of the keyhole is dynamically opened and closed. When the bottom of the keyhole is closed, the molten metal at the bottom of the back keyhole wall flows upwards along the fusion line. When the bottom of the keyhole is opened, few spatters can be seen around the keyhole at the top surface, two flow patterns exists in the rear part of the keyhole: a portion of molten metal flows upwards along the fusion line, other portion of molten metal flows to the bottom of the keyhole, which promote the spatter formation at the bottom of the keyhole rear wall.

Low-Temperature Friction-Stir Welding of 2024 Aluminum

NASA Technical Reports Server (NTRS)

Benavides, S.; Li, Y.; Murr, L. E.; Brown, D.; McClure, J. C.

1998-01-01

Solid state friction-stir welding (FSW) has been demonstrated to involve dynamic recrystallization producing ultra-fine, equiaxed grain structures to facilitate superplastic deformation as the welding or joining mechanism. However, the average residual, equiaxed, grain size in the weld zone has ranged from roughly 0.5 micron to slightly more than 10 micron, and the larger weld zone grain sizes have been characterized as residual or static grain growth as a consequence of the temperatures in the weld zone (where center-line temperatures in the FSW of 6061 Al have been shown to be as high as 480C or -0.8 T(sub M) where T(sub M) is the absolute melting temperature)). In addition, the average residual weld zone grain size has been observed to increase near the top of the weld, and to decrease with distance on either side of the weld-zone centerline, an d this corresponds roughly to temperature variations within the weld zone. The residual grain size also generally decreases with decreasing FSW tool rotation speed. These observations are consistent with the general rules for recrystallization where the recrystallized grain size decreases with increasing strain (or deformation) at constant strain rate, or with increasing strain-rate, or with increasing strain rate at constant strain; especially at lower ambient temperatures, (or annealing temperatures). Since the recrystallization temperature also decreases with increasing strain rate, the FSW process is somewhat complicated because the ambient temperature, the frictional heating fraction, and the adiabatic heating fraction )proportional to the product of strain and strain-rate) will all influence both the recrystallization and growth within the FSW zone. Significantly reducing the ambient temperature of the base metal or work pieces to be welded would be expected to reduce the residual weld-zone grain size. The practical consequences of this temperature reduction would be the achievement of low temperature welding. This

Microstructure Evolution during Friction Stir Welding of Mill-Annealed Ti-6Al-4V (Preprint)

DTIC Science & Technology

2011-05-01

welding . One of the primary concerns regarding FSW of higher temperature materials like titanium is the welding tool. High temperature materials... welds as compared to aluminum alloys. This is related to the low thermal conductivity of titanium alloys which is typically lower than that of the...of the tools and workpieces in aluminum and titanium friction stir welds . Aluminum has a greater conductivity and thermal diffusivity than the tool

Fusion welding experiments under low-gravity conditions using aircraft

NASA Astrophysics Data System (ADS)

Masubuchi, Koichi; Nayama, Michisuke

A series of gas tungsten arc welding experiments under low-gravity conditions created using parabolic flight of aircraft were performed. The materials used were aluminum and 2219 aluminum alloy. Welding was conducted in a small chamber filled with 100 percent argon gas, and the power source was a set of storage batteries. While welding was conducted, CCD image of welding phenomena, welding current, voltage, and the gravity level of the welding table were recorded continuously. It was found that sound welds can be obtained under low-gravity conditions. The bead appearance of the weld bead made under low-gravity conditions was very smooth and flat with no ripple lines which normally exist in welds made on the earth. The observed shape of the arc plasma under low-gravity conditions was larger than that made under normal gravity condition, but the difference was not so significant. Welds made under low-gravity conditions tend to contain more porosity compared with welds made under the earth conditions.

Stability of Full Penetration, Flat Position Weld Pools

NASA Technical Reports Server (NTRS)

Nunes, Arthur C., Jr.; Coan, Al. B.

1999-01-01

The dynamics of the dropthrough distance of a full penetration, flat position weld pool is described. Close to incipient root side penetration the dropthrough is metastable, so that a small drop in power can cause a loss of penetration if not followed soon enough by a compensating rise in power. The SPA (Soft Plasma Arc) process with higher pressure on top of the weld pool loses penetration more quickly than the GTA (Gas Tungsten Arc) process. 2195 aluminum-lithium alloy with a lower surface tension loses penetration more quickly than 2219 aluminum alloy. An instance of loss of penetration of a SPA weld in 2195 aluminum-lithium alloy is discussed in the light of the model.

Laser welding aluminum without filler metal using continuous wave and pulsed Nd:YAG lasers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bransch, H.N.

1994-12-31

A problem with automotive aluminum tubing applications, particularly for air conditioning heat exchanger assemblies, is terminating the tube reliably and inexpensively. An alternative to upsetting and mchining threads to the tube end is welding a nut (made from a stronger, easily machinable alloy such as Al 5456 or Al 6061) to lengths of tubing (made from a softer alloy such as Al 3003). Laser welding was investigated in order to reduce heat input and increase process speeds copared to brazing or gas metal arc welding (GMAW). Nd:YAG lasers were selected as beam source because of better absorptivity of the wavelengthmore » compared to CO{sub 2} lasers and simplified tooling with fiber optic beam delivery. It wa determined that a pulsed Nd:YAG laser produced 1.0 mm penetration at 0.3 m/min with 400 W average power, and 1.0 mm penetration at 0.75 m/min with 1000 W average power, however, an Al 4047 filler metal was required to eliminate solidification cracking. A 1900 W CW laser could weld the Al 3003 tube to the Al 5456 nut without filler metal, however, there was insufficient penetration (0.25 mm) to meet the mechanical and hermeticity requirements. To enhance penetration, but still reduce the tendency for hot cracking, the 1900 W average power beam was sine wave modulated from 400 W to 3600 W at 250 Hz and usd to weld the Al 3003 directly to the Al 5456. These parameters produced 1.2 mm penetration at 1.2 m/min without significant cracking and without using a filler metal. In addition, the welds passed all hermeticity and tensile strength tests. This combination of materials, joint design, and laser parameters produced tube assemblies that passed a leak check (300 psi nitrogen in 60{degrees}C water for 1 min) and tensile (tube breakage 100 mm from the joint, 5.2 kN tensile strength).« less

Tool Forces Developed During Friction Stir Welding

NASA Technical Reports Server (NTRS)

Melendez, M.; Tang, W.; Schmidt, C.; McClure, J. C.; Nunes, A. C.; Murr, L. E.

2003-01-01

This paper will describe a technique for measuring the various forces and the torque that exist on the Friction Stir Welding pin tool. Results for various plunge depths, weld speeds, rotational speed, and tool configurations will be presented. Welds made on 6061 aluminum with typical welding conditions require a downward force of 2800 lbs. (12.5 kN) a longitudinal force in the direction of motion of 300 lbs (1.33 kN), a transverse force in the omega x v direction of 30 lbs (135 N). Aluminum 2195 under typical weld conditions requires a downward force of 3100 lbs. (1.38 kN), a longitudinal force of 920 lbs. (4.1 kN), and a transverse force of 45 lbs. (200 N) in the omega x v direction.

Method of forming grooves in the [011] crystalline direction

NASA Technical Reports Server (NTRS)

Marinelli, Donald Paul (Inventor)

1977-01-01

An A-B etchant is applied to a (100) surface of a body of semiconductor material, a portion of which along the (100) surface of the body is either gallium arsenide or gallium aluminum arsenide. The etchant is applied for at least 15 seconds at a temperature of approximately 80.degree. C. The A-B etchant is a solution by weight percent of 47.5%, water, 0.2% silver nitrate, 23.8% chromium trioxide and 28.5% of a 48% aqueous solution of hydrofluoric acid. As a result of the application of the A-B etchant a pattern of elongated etch pits form having their longitudinal axes along the [011] crystalline direction. Grooves are formed in the body at a surface opposite the (100) surface on which was applied the etchant. The grooves are formed along the [011] crystalline direction by aligning the longitudinal axes of the grooves with the longitudinal axes of the etch pits.

2195 Aluminum-Copper-Lithium Friction Plug Welding Development

NASA Technical Reports Server (NTRS)

Takeshita, Rike P.; Hartley, Paula J.; Baker, Kent S.

1997-01-01

Technology developments and applications of friction plug welding is presented. This friction repair welding technology is being studied for implementation on the Space Transportation System's Super Light Weight External Tank. Single plug repairs will be used on a vast majority of weld defects, however, linear defects of up to several inches can be repaired by overlapping plug welds. Methods and results of tensile, bend, simulated service, surface crack tension and other tests at room and cryogenic temperatures is discussed. Attempts to implement Friction Plug Welding has led to both tool and process changes in an attempt to minimize expansive tooling and lengthy implementation times. Process control equipment and data storage methods intended for large scale production will also be addressed. Benefits include increased strength and toughness, decreased weld repair time, automated and highly reliable process, and a lower probability of having to re-repair defect locations.

Influence of Filler Alloy Composition and Process Parameters on the Intermetallic Layer Thickness in Single-Sided Cold Metal Transfer Welding of Aluminum-Steel Blanks

NASA Astrophysics Data System (ADS)

Silvayeh, Zahra; Vallant, Rudolf; Sommitsch, Christof; Götzinger, Bruno; Karner, Werner; Hartmann, Matthias

2017-11-01

Hybrid components made of aluminum alloys and high-strength steels are typically used in automotive lightweight applications. Dissimilar joining of these materials is quite challenging; however, it is mandatory in order to produce multimaterial car body structures. Since especially welding of tailored blanks is of utmost interest, single-sided Cold Metal Transfer butt welding of thin sheets of aluminum alloy EN AW 6014 T4 and galvanized dual-phase steel HCT 450 X + ZE 75/75 was experimentally investigated in this study. The influence of different filler alloy compositions and welding process parameters on the thickness of the intermetallic layer, which forms between the weld seam and the steel sheet, was studied. The microstructures of the weld seam and of the intermetallic layer were characterized using conventional optical light microscopy and scanning electron microscopy. The results reveal that increasing the heat input and decreasing the cooling intensity tend to increase the layer thickness. The silicon content of the filler alloy has the strongest influence on the thickness of the intermetallic layer, whereas the magnesium and scandium contents of the filler alloy influence the cracking tendency. The layer thickness is not uniform and shows spatial variations along the bonding interface. The thinnest intermetallic layer (mean thickness < 4 µm) is obtained using the silicon-rich filler Al-3Si-1Mn, but the layer is more than twice as thick when different low-silicon fillers are used.

Metallic glass coating on metals plate by adjusted explosive welding technique

NASA Astrophysics Data System (ADS)

Liu, W. D.; Liu, K. X.; Chen, Q. Y.; Wang, J. T.; Yan, H. H.; Li, X. J.

2009-09-01

Using an adjusted explosive welding technique, an aluminum plate has been coated by a Fe-based metallic glass foil in this work. Scanning electronic micrographs reveal a defect-free metallurgical bonding between the Fe-based metallic glass foil and the aluminum plate. Experimental evidence indicates that the Fe-based metallic glass foil almost retains its amorphous state and mechanical properties after the explosive welding process. Additionally, the detailed explosive welding process has been simulated by a self-developed hydro-code and the bonding mechanism has been investigated by numerical analysis. The successful welding between the Fe-based metallic glass foil and the aluminum plate provides a new way to obtain amorphous coating on general metal substrates.

Microstructure characterization and charpy toughness of P91 weldment for as-welded, post-weld heat treatment and normalizing & tempering heat treatment

NASA Astrophysics Data System (ADS)

Pandey, Chandan; Mahapatra, M. M.; Kumar, Pradeep; Giri, A.

2017-09-01

The effect of weld groove design and heat treatment on microstructure evolution and Charpy toughness of P91 pipe weldments was studied. The P91 pipe weldments were subjected to subcritical post weld heat treatment (760 °C-2 h) and normalizing/tempering conditions (normalized-1040 °C/40 min, air cooled; tempered 760 °C/2 h, air cooled) were employed. The influence of subsequent PWHT and N&T treatment on the microstructure of various zone of P91 pipe weldments were also investigated. The present investigation also described the effect of PWHT and N&T treatment on hardness, grain size, precipitate size, inter-particle spacing and fraction area of precipitates present in each zone of P91 pipe weldments. The result indicated great impact of heat treatment on the Charpy toughness and microstructure evolution of P91 weldments. The N&T treatment was found to be more effective heat treatment compared to subsequent PWHT. Charpy toughness value was found to be higher for narrow-groove design as compared to conventional V-groove design.

Computational Analysis of Material Flow During Friction Stir Welding of AA5059 Aluminum Alloys

NASA Astrophysics Data System (ADS)

Grujicic, M.; Arakere, G.; Pandurangan, B.; Ochterbeck, J. M.; Yen, C.-F.; Cheeseman, B. A.; Reynolds, A. P.; Sutton, M. A.

2012-09-01

Workpiece material flow and stirring/mixing during the friction stir welding (FSW) process are investigated computationally. Within the numerical model of the FSW process, the FSW tool is treated as a Lagrangian component while the workpiece material is treated as an Eulerian component. The employed coupled Eulerian/Lagrangian computational analysis of the welding process was of a two-way thermo-mechanical character (i.e., frictional-sliding/plastic-work dissipation is taken to act as a heat source in the thermal-energy balance equation) while temperature is allowed to affect mechanical aspects of the model through temperature-dependent material properties. The workpiece material (AA5059, solid-solution strengthened and strain-hardened aluminum alloy) is represented using a modified version of the classical Johnson-Cook model (within which the strain-hardening term is augmented to take into account for the effect of dynamic recrystallization) while the FSW tool material (AISI H13 tool steel) is modeled as an isotropic linear-elastic material. Within the analysis, the effects of some of the FSW key process parameters are investigated (e.g., weld pitch, tool tilt-angle, and the tool pin-size). The results pertaining to the material flow during FSW are compared with their experimental counterparts. It is found that, for the most part, experimentally observed material-flow characteristics are reproduced within the current FSW-process model.

Numerical analysis on temperature field in single-wire flux-aided backing-submerged arc welding

NASA Astrophysics Data System (ADS)

Pu, Juan; Wu, Ming Fang; Pan, Haichao

2017-07-01

Single-wire flux-aided backing-submerged arc welding (FAB-SAW) technology has been widely used to weld thick steel plate due to its easy assembly and high heat input. The microstructure and property of welded joint are closely related to the thermal field of FAB-SAW process. In this research, the feature of thermal field for single-wire FAB-SAW was investigated. Based on the heat transfer mechanism, a three-dimensional transient model for thermal field was developed based on the influence of steel thickness, groove angle and ceramic backing. The temperature profile in single-wire FAB-SAW of D36 steel under different welding conditions was simulated by ANSYS. The characteristic of thermal field was analyzed and the influences of groove angle on temperature field for different plate thicknesses were discussed. The calculated geometries and dimensions of weld cross-section under different conditions show a good agreement with the experimental results. This newly built model can describe the thermal field accurately, which would be helpful to understanding the thermophysical mechanism of FAB-SAW and optimizing the welding process.

Internal Stress Distribution Measurement of TIG Welded SUS304 Samples Using Neutron Diffraction Technique

NASA Astrophysics Data System (ADS)

Muslih, M. Refai; Sumirat, I.; Sairun; Purwanta

2008-03-01

The distribution of residual stress of SUS304 samples that were undergone TIG welding process with four different electric currents has been measured. The welding has been done in the middle part of the samples that was previously grooved by milling machine. Before they were welded the samples were annealed at 650 degree Celsius for one hour. The annealing process was done to eliminate residual stress generated by grooving process so that the residual stress within the samples was merely produced from welding process. The calculation of distribution of residual stress was carried out by measuring the strains within crystal planes of Fe(220) SUS304. Strain, Young modulus, and Poisson ratio of Fe(220) SUS304 were measured using DN1-M neutron diffractometer. Young modulus and Poisson ratio of Fe(220) SUS304 sample were measured in-situ. The result of calculations showed that distribution of residual stress of SUS304 in the vicinity of welded area is influenced both by treatments given at the samples-making process and by the electric current used during welding process.

Effect of thermal exposure, forming, and welding on high-temperature, dispersion-strengthened aluminum alloy: Al-8Fe-1V-2Si

NASA Technical Reports Server (NTRS)

Kennedy, J. R.; Gilman, P. S.; Zedalis, M. S.; Skinner, D. J.; Peltier, J. M.

1991-01-01

The feasibility of applying conventional hot forming and welding methods to high temperature aluminum alloy, Al-8Fe-1V-2Si (FVS812), for structural applications and the effect of thermal exposure on mechanical properties were determined. FVS812 (AA8009) sheet exhibited good hot forming and resistance welding characteristics. It was brake formed to 90 deg bends (0.5T bend radius) at temperatures greater than or equal to 390 C (730 F), indicating the feasibility of fabricating basic shapes, such as angles and zees. Hot forming of simple contoured-flanged parts was demonstrated. Resistance spot welds with good static and fatigue strength at room and elevated temperatures were readily produced. Extended vacuum degassing during billet fabrication reduced porosity in fusion and resistance welds. However, electron beam welding was not possible because of extreme degassing during welding, and gas-tungsten-arc welds were not acceptable because of severely degraded mechanical properties. The FVS812 alloy exhibited excellent high temperature strength stability after thermal exposures up to 315 C (600 F) for 1000 h. Extended billet degassing appeared to generally improve tensile ductility, fatigue strength, and notch toughness. But the effects of billet degassing and thermal exposure on properties need to be further clarified. The manufacture of zee-stiffened, riveted, and resistance-spot-welded compression panels was demonstrated.

Diode lasers for direct application by utilizing a trepanning optic for remote oscillation welding of aluminum and copper

NASA Astrophysics Data System (ADS)

Fritsche, Haro; Müller, Norbert; Ferrario, Fabio; Fetissow, Sebastian; Grohe, Andreas; Hagen, Thomas; Steger, Ronny; Katzemaikat, Tristan; Ashkenasi, David; Gries, Wolfgang

2017-02-01

We report the first direct diode laser module integrated with a trepanning optic for remote oscillation welding. The trepanning optic is assembled with a collimated DirectProcess 900 laser engine. This modular laser is based on single emitters and beam combiners to achieve fiber coupled modules with a beam parameter product or BPP < 8 mm mrad at all power levels up to 1 kW, as well as free space collimated outputs with even lower BPP. The initial design consists in vertically stacking several diodes in the fast axis which leads to a rectangular output of about 100 W with BPP of <3.5 mm*mrad in the fast axis and <5 mm*mrad in the slow axis. Next, further power scaling is accomplished by polarization combining and wavelength multiplexing yielding high optical efficiencies of more than 80% and resulting in a building block module with over 500 W launched into a 100 μm fiber with 0.15 NA. The beam profile of the free space module remains rectangular, with a nearly flat top and conserves the beam parameter product of the original vertical stack without the power loss of fiber coupling. The 500 W building blocks feature a highly flexible emitting wavelength bandwidth. New wavelengths can be configured by simply exchanging parts and without modifying the production process. This design principle provides the option to adapt the wavelength configuration to match a broad set of applications, from the UV to the visible and to the far IR depending on the commercial availability of laser diodes. This opens numerous additional applications like laser pumping, scientific and medical applications, as well as materials processing applications such as cutting and welding of copper aluminum or steel. Furthermore, the module's short lead lengths enable very short pulses. Integrated with electronics, the module's pulse width can be adjusted from micro-seconds to cw mode operation by simple software commands. An optical setup can be directly attached instead of a fiber to the laser

Neural Network Prediction of Aluminum-Lithium Weld Strengths from Acoustic Emission Amplitude Data

NASA Technical Reports Server (NTRS)

Hill, Eric v. K.; Israel, Peggy L.; Knotts, Gregory L.

1993-01-01

Acoustic Emission (AE) flaw growth activity was monitored in aluminum-lithium weld specimens from the onset tensile loading to failure. Data on actual ultimate strengths together with AE data from the beginning of loading up to 25 percent of the expected ultimate strength were used to train a backpropagation neural network to predict ultimate strengths. Architecturally, the fully interconnected network consisted of an input layer for the AE amplitude data, a hidden layer to accommodate failure mechanism mapping, and an output layer for ultimate strength prediction. The trained network was the applied to the prediction of ultimate strengths in the remaining six specimens. The worst case prediction error was found to be +2.6 percent.

Development of method to remove weld scallop and ceramic backing material of wedge type and its application

NASA Astrophysics Data System (ADS)

Kang, Sung-Koo; Yang, Jong-Soo; Kim, Ho-Kyung

2015-06-01

The weld scallop has been used for joining T-bars. There are a lot of weld scallops in shipbuilding. It is difficult to perform scallop welding due to the inconvenient welding position. This results in many problems such as porosity, slag inclusion, etc. In this study, a new method is devised to remove weld scallops by incorporating a Ceramic Backing Material (CBM). The weld scallop is removed by an elongation of the v groove. In order to insert a CBM into the groove without a weld scallop, a wedge-shaped CBM is developed. The top side of the developed CBM is similar to the shape of a general back bead. The bottom surface has a saw-toothed shape for cutting at a suitable length. This can be attached to the root side of a face plate using adhesive tape, just like a general CBM. Welding experiments in normal and abnormal conditions are carried out and the possibility of burn-through is examined. This CBM's applicability to shipbuilding is verified.

Intermetallic alloy welding wires and method for fabricating the same

DOEpatents

Santella, M.L.; Sikka, V.K.

1996-06-11

Welding wires for welding together intermetallic alloys of nickel aluminides, nickel-iron aluminides, iron aluminides, or titanium aluminides, and preferably including additional alloying constituents are fabricated as two-component, clad structures in which one component contains the primary alloying constituent(s) except for aluminum and the other component contains the aluminum constituent. This two-component approach for fabricating the welding wire overcomes the difficulties associated with mechanically forming welding wires from intermetallic alloys which possess high strength and limited ductilities at elevated temperatures normally employed in conventional metal working processes. The composition of the clad welding wires is readily tailored so that the welding wire composition when melted will form an alloy defined by the weld deposit which substantially corresponds to the composition of the intermetallic alloy being joined. 4 figs.

Intermetallic alloy welding wires and method for fabricating the same

DOEpatents

Santella, Michael L.; Sikka, Vinod K.

1996-01-01

Welding wires for welding together intermetallic alloys of nickel aluminides, nickel-iron aluminides, iron aluminides, or titanium aluminides, and preferably including additional alloying constituents are fabricated as two-component, clad structures in which one component contains the primary alloying constituent(s) except for aluminum and the other component contains the aluminum constituent. This two-component approach for fabricating the welding wire overcomes the difficulties associated with mechanically forming welding wires from intermetallic alloys which possess high strength and limited ductilities at elevated temperatures normally employed in conventional metal working processes. The composition of the clad welding wires is readily tailored so that the welding wire composition when melted will form an alloy defined by the weld deposit which substantially corresponds to the composition of the intermetallic alloy being joined.

Automatic orbital GTAW welding: Highest quality welds for tomorrow's high-performance systems

NASA Technical Reports Server (NTRS)

Henon, B. K.

1985-01-01

Automatic orbital gas tungsten arc welding (GTAW) or TIG welding is certain to play an increasingly prominent role in tomorrow's technology. The welds are of the highest quality and the repeatability of automatic weldings is vastly superior to that of manual welding. Since less heat is applied to the weld during automatic welding than manual welding, there is less change in the metallurgical properties of the parent material. The possibility of accurate control and the cleanliness of the automatic GTAW welding process make it highly suitable to the welding of the more exotic and expensive materials which are now widely used in the aerospace and hydrospace industries. Titanium, stainless steel, Inconel, and Incoloy, as well as, aluminum can all be welded to the highest quality specifications automatically. Automatic orbital GTAW equipment is available for the fusion butt welding of tube-to-tube, as well as, tube to autobuttweld fittings. The same equipment can also be used for the fusion butt welding of up to 6 inch pipe with a wall thickness of up to 0.154 inches.

Investigation of the material flow and texture evolution in friction-stir welded aluminum alloy

NASA Astrophysics Data System (ADS)

Kang, Suk Hoon; Han, Heung Nam; Oh, Kyu Hwan; Cho, Jae-Hyung; Lee, Chang Gil; Kim, Sung-Joon

2009-12-01

The material flow and crystallographic orientation in aluminum alloy sheets joined by friction stir welding (FSW) were investigated by electron back scattered diffraction (EBSD). The microstructure and microtexture of the material near the stir zone was found to be influenced by the rotational behavior of the tool pin. It was found that, during FSW, the forward movement of the tool pin resulted in loose contact between the tool pin and the receding material at the advancing side. This material behavior inside the joined aluminum plates was also observed by an X-ray micrograph by inlaying a gold marker into the plates. As the advancing speed of the tool increases at a given rotation speed, the loose contact region widens. As the microtexture of the material near the stir zone is very close to the simple shear texture on the basis of the frame of the tool pin in the normal and tangent directions, the amount of incompletely rotated material due to the loose contact could be estimated from the tilt angle of the shear texture in the pole figure around the key hole.

Industrial laser welding evaluation study

NASA Technical Reports Server (NTRS)

Hella, R.; Locke, E.; Ream, S.

1974-01-01

High power laser welding was evaluated for fabricating space vehicle boosters. This evaluation was made for 1/4 in. and 1/2 in. aluminum (2219) and 1/4 in. and 1/2 in. D6AC steel. The Avco HPL 10 kW industrial laser was used to perform the evaluation. The objective has been achieved through the completion of the following technical tasks: (1) parameter study to optimize welding and material parameters; (2) preparation of welded panels for MSFC evaluation; and (3) demonstration of the repeatability of laser welding equipment. In addition, the design concept for a laser welding system capable of welding large space vehicle boosters has been developed.

Fume generation rates for stainless steel, nickel and aluminum alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Castner, H.R.

1996-12-01

This paper describes a study of the effects of pulsed welding current on fume produced during gas metal arc welding (GMAW) of stainless steel, nickel, and aluminum alloys. This is an extension of earlier studies of mild steel electrode wire. Reduction of welding fume is important because steady current GMAW of stainless steels and nickel alloys may produce fume that exceeds recommended worker exposure limits for some of the fume constituents. Fume generation from aluminum alloy ER5356 was studied because steady current welding with this alloy produces much higher fume generation rates than ER4043 alloy electrode wire. This work showsmore » that pulsed current can reduce GMAW fume generation rates for Er308L, ER310, and ER312 stainless steel, ERNiCr-3 nickel alloy, and ER5356 aluminum-magnesium alloy electrode wires.« less

Colossal super saturation of oxygen at the iron-aluminum interfaces fabricated using solid state welding

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sridharan, Niyanth; Isheim, D.; Seidman, David N.

Solid state joining is achieved in three steps, (i) interface asperity deformation, (ii) oxide dispersion, followed by (iii) atomic contact and bonding. Atomically clean metallic surfaces without an oxide layer bond spontaneously. Despite its importance the oxide dispersion mechanism is not well studied. In this work the first ever atom probe study of iron-aluminum solid state welds show that the oxygen concentration at the interface is 20 at.%. This is significantly lower than any equilibrium oxide concentration. Here, we therefore propose that the high-strain rate deformation at the interfaces renders the oxide unstable resulting in the observed concentration of oxygen.

Colossal super saturation of oxygen at the iron-aluminum interfaces fabricated using solid state welding

DOE PAGES

Sridharan, Niyanth; Isheim, D.; Seidman, David N.; ...

2016-12-14

Solid state joining is achieved in three steps, (i) interface asperity deformation, (ii) oxide dispersion, followed by (iii) atomic contact and bonding. Atomically clean metallic surfaces without an oxide layer bond spontaneously. Despite its importance the oxide dispersion mechanism is not well studied. In this work the first ever atom probe study of iron-aluminum solid state welds show that the oxygen concentration at the interface is 20 at.%. This is significantly lower than any equilibrium oxide concentration. Here, we therefore propose that the high-strain rate deformation at the interfaces renders the oxide unstable resulting in the observed concentration of oxygen.

Gravitational effects on weld pool shape and microstructural evolution during gas tungsten arc and laser beam welding on 304 stainless steel, nickel, and aluminum-4 wt.% copper alloy

NASA Astrophysics Data System (ADS)

Kang, Namhyun

The objective of the present work was to investigate effects of gravitational (acceleration) level and orientation on Ni 200 alloy (99.5% Ni purity), 304 stainless steel, and Al-4 wt.% Cu alloy during gas tungsten arc welding (GTAW) and laser beam welding (LBW). Main characterization was focused on the weld pool shape, microstructure, and solute distribution as a function of gravitational level and orientation. The welds were divided into two classes, i.e., 'stable' and 'unstable' welds, in view of the variation of weld pool shape as a function of gravitational level and orientation. In general, higher arc current and translational GTAW produced more significant effects of gravitational orientation on the weld pool shape than the case of lower arc current and spot welding. Cross-sectional area (CSA) was a secondary factor in determining the stability of weld pool shape. For the 'stable' weld of 304 stainless steel GTAW, the II-U weld showed less convexity in the pool bottom and more depression of the free surface, therefore producing deeper penetration (10--20%) than the case of II-D weld. The II-D weld of 304 stainless steel showed 31% deeper penetration, 28% narrower width, and more hemispherical shape of the weld pool than the case of II-U weld. For GTAW on 304 stainless steel, gravitational level variation from low gravity (LG ≈ 1.2 go) to high gravity (HG ≈ 1.8 go) caused 10% increase in width and 10% decrease in depth while maintaining the overall weld pool volume. Furthermore, LBW on 304 stainless steels showed mostly constant shape of weld pool as a function of gravitational orientation. GTAW on Ni showed similar trends of weld pool shape compared with GTAW on 304 stainless steel, i.e., the weld pool became unstable by showing more penetration in the II-D weld for slower arc translational velocity (V a) and larger weld pool size. However, the Ni weld pool shape had greater stability of the weld pool shape with respect to the gravitational orientation

Superhydrophobic surface prepared by micro-milling and WEDM on aluminum alloy

NASA Astrophysics Data System (ADS)

Yanling, Wan; Jian, Yang; Huadong, Yu

2018-06-01

To simulate the hydrophobic microstructure of rice leaf surface, high-speed precision micro-milling machine was used to fabricate micro groove array structure on the surface of aluminum alloy. The micro-and nanostructure was constructed on the surface of the grooved convex platform by Wire Cut Electrical Discharge Machining (WEDM). The surface morphology and hydrophobic properties of the aluminum alloy microstructures fabricated by two processing methods were observed respectively, and the hydrophobic mechanism was analyzed. The results show that the contact angle was effectively improved from 49° up to 158.4° in the vertical direction, and 146.7° in the parallel direction. The change of surface wettability from hydrophilic to hydrophobic was realized. By comparison, the micro-and nanostructure fabricated by WEDM had improved the hydrophobic stability of the aluminum alloy surface while enlarging the contact Angle, and the micro-milling groove structure further amplified the contact angle and greatly reduced the contact area of the water droplet, it was also observed that the drop took longer to completely spread on the sample after WEDM.

Non-destructive three-dimensional evaluation of pores at different welded joints and their effects on joints strength.

PubMed

Nomoto, Rie; Takayama, Yasuko; Tsuchida, Fujio; Nakajima, Hiroyuki

2010-12-01

The purpose of this study was to measure the porosity in different laser welded cast alloys non-destructively using X-ray micro-focus computerized tomography (micro-CT) and to evaluate the effect of porosity on the tensile strength of the welded joints. The welding procedure was conducted in rectangular cast metals, CoCr, Ti and platinum added gold alloy (AuPt). The metal plates were butted CoCr to CoCr (CoCr/CoCr) or Ti to Ti (Ti/Ti) for welding of similar metals and Ti to AuPt (Ti/AuPt) for welding of dissimilar metals. Specimens were welded under several laser-welding conditions; with groove (normal), without groove (no groove), spatter, crack, or no overlapped welding (no overlap) (n=5). Porosity in the welded area was evaluated using a micro-CT. Tensile strength of the welded specimens was measured at a crosshead speed of 1mm/min. Multiple comparisons of the group means were performed using ANOVA and Fisher's multiple comparisons test (α=.05). The relationship between the porosity and the tensile strength was investigated with a regression analysis. Three-dimensional images of Ti/AuPt could not be obtained due to metal artifacts and the tensile specimens of Ti/AuPt were debonded prior to the tensile test. All other welded specimens had porosity in the welded area and the porosities ranged from 0.01% to 0.17%. The fractures of most of the CoCr/CoCr and Ti/Ti specimens occurred in the parent metals. Joint strength had no relationship with the porosity in the welded area (R(2)=0.148 for CoCr/CoCr, R(2)=0.088 for Ti/Ti, respectively). The small amount of porosity caused by the laser-welding procedures did not affect the joint strength. The joint strength of Ti/AuPt was too weak to be used clinically. Copyright © 2010 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Variable-Polarity Plasma Arc Welding Of Alloy 2219

NASA Technical Reports Server (NTRS)

Walsh, Daniel W.; Nunes, Arthur C., Jr.

1989-01-01

Report presents results of study of variable-polarity plasma arc (VPPA) welding of aluminum alloy 2219. Consists of two parts: Examination of effects of microsegregation and transient weld stress on macrosegregation in weld pool and, electrical characterization of straight- and reverse-polarity portions of arc cycle.

Efficient Welding Fabrication of Extruded Aluminum Mat Panels

DTIC Science & Technology

1991-09-01

3-34 Fig. 3-18 Measured hydrogen contents of 3003 and 2219 alloy welds deposited by GTAW with contaminated shielding gas...downhill, and (c) overhead welds (Ref. 34) ..................................... 3-37 Fig. 3-21 Effect of GTAW current on weld porosity and the rate of...radius, connecting a slight tapered section to a straight one at the metal exit point. AISI H Class, air hardening chromium hot work tool steel, is a

Stress Corrosion Cracking Behavior of Multipass TIG-Welded AA2219 Aluminum Alloy in 3.5 wt pct NaCl Solution

NASA Astrophysics Data System (ADS)

Venugopal, A.; Sreekumar, K.; Raja, V. S.

2012-09-01

The stress corrosion cracking (SCC) behavior of the AA2219 aluminum alloy in the single-pass (SP) and multipass (MP) welded conditions was examined and compared with that of the base metal (BM) in 3.5 wt pct NaCl solution using a slow-strain-rate technique (SSRT). The reduction in ductility was used as a parameter to evaluate the SCC susceptibility of both the BM and welded joints. The results showed that the ductility ratio ( ɛ NaCl/( ɛ air) was 0.97 and 0.96, respectively, for the BM and MP welded joint, and the same was marginally reduced to 0.9 for the SP welded joint. The fractographic examination of the failed samples revealed a typical ductile cracking morphology for all the base and welded joints, indicating the good environmental cracking resistance of this alloy under all welded conditions. To understand the decrease in the ductility of the SP welded joint, preexposure SSRT followed by microstructural observations were made, which showed that the decrease in ductility ratio of the SP welded joint was caused by the electrochemical pitting that assisted the nucleation of cracks in the form of corrosion induced mechanical cracking rather than true SCC failure of the alloy. The microstructural examination and polarization tests demonstrated a clear grain boundary (GB) sensitization of the PMZ, resulting in severe galvanic corrosion of the SP weld joint, which initiated the necessary conditions for the localized corrosion and cracking along the PMZ. The absence of PMZ and a refined fusion zone (FZ) structure because of the lesser heat input and postweld heating effect improved the galvanic corrosion resistance of the MP welded joint greatly, and thus, failure occurred along the FZ.

Residual Stresses and Critical Initial Flaw Size Analyses of Welds

NASA Technical Reports Server (NTRS)

Brust, Frederick W.; Raju, Ivatury, S.; Dawocke, David S.; Cheston, Derrick

2009-01-01

An independent assessment was conducted to determine the critical initial flaw size (CIFS) for the flange-to-skin weld in the Ares I-X Upper Stage Simulator (USS). A series of weld analyses are performed to determine the residual stresses in a critical region of the USS. Weld residual stresses both increase constraint and mean stress thereby having an important effect on the fatigue life. The purpose of the weld analyses was to model the weld process using a variety of sequences to determine the 'best' sequence in terms of weld residual stresses and distortions. The many factors examined in this study include weld design (single-V, double-V groove), weld sequence, boundary conditions, and material properties, among others. The results of this weld analysis are included with service loads to perform a fatigue and critical initial flaw size evaluation.

Effect of Multipass TIG and Activated TIG Welding Process on the Thermo-Mechanical Behavior of 316LN Stainless Steel Weld Joints

NASA Astrophysics Data System (ADS)

Ganesh, K. C.; Balasubramanian, K. R.; Vasudevan, M.; Vasantharaja, P.; Chandrasekhar, N.

2016-04-01

The primary objective of this work was to develop a finite element model to predict the thermo-mechanical behavior of an activated tungsten inert gas (ATIG)-welded joint. The ATIG-welded joint was fabricated using 10 mm thickness of 316LN stainless steel plates in a single pass. To distinguish the merits of ATIG welding process, it was compared with manual multipass tungsten inert gas (MPTIG)-welded joint. The ATIG-welded joint was fabricated with square butt edge configuration using an activating flux developed in-house. The MPTIG-welded joint was fabricated in thirteen passes with V-groove edge configuration. The finite element model was developed to predict the transient temperature, residual stress, and distortion of the welded joints. Also, microhardness, impact toughness, tensile strength, ferrite measurement, and microstructure were characterized. Since most of the recent publications of ATIG-welded joint was focused on the molten weld pool dynamics, this research work gives an insight on the thermo-mechanical behavior of ATIG-welded joint over MPTIG-welded joint.

An Assessment of Molten Metal Detachment Hazards During Electron Beam Welding in the Space Shuttle Bay at LEO for the International Space Welding Experiment

NASA Technical Reports Server (NTRS)

Fragomeni, James M.

1996-01-01

In 1997, the United States [NASA] and the Paton Electric Welding Institute are scheduled to cooperate in a flight demonstration on the U.S. Space Shuttle to demonstrate the feasibility of welding in space for a possible repair option for the International Space Station Alpha. This endeavor, known as the International Space Welding Experiment (ISWE), will involve astronauts performing various welding exercises such as brazing, cutting, welding, and coating using an electron beam space welding system that was developed by the E.O. Paton Electric Welding Institute (PWI), Kiev Ukraine. This electron beam welding system known as the "Universal Weld System" consists of hand tools capable of brazing, cutting, autogeneous welding, and coating using an 8 kV (8000 volts) electron beam. The electron beam hand tools have also been developed by the Paton Welding Institute with greater capabilities than the original hand tool, including filler wire feeding, to be used with the Universal Weld System on the U.S. Space Shuttle Bay as part of ISWE. The hand tool(s) known as the Ukrainian Universal Hand [Electron Beam Welding] Tool (UHT) will be utilized for the ISWE Space Shuttle flight welding exercises to perform welding on various metal alloy samples. A total of 61 metal alloy samples, which include 304 stainless steel, Ti-6AI-4V, 2219 aluminum, and 5456 aluminum alloys, have been provided by NASA for the ISWE electron beam welding exercises using the UHT. These samples were chosen to replicate both the U.S. and Russian module materials. The ISWE requires extravehicular activity (EVA) of two astronauts to perform the space shuttle electron beam welding operations of the 61 alloy samples. This study was undertaken to determine if a hazard could exist with ISWE during the electron beam welding exercises in the Space Shuttle Bay using the Ukrainian Universal Weld System with the UHT. The safety issue has been raised with regard to molten metal detachments as a result of several

Method for laser welding a fin and a tube

DOEpatents

Fuerschbach, Phillip W.; Mahoney, A. Roderick; Milewski, John O

2001-01-01

A method of laser welding a planar metal surface to a cylindrical metal surface is provided, first placing a planar metal surface into approximate contact with a cylindrical metal surface to form a juncture area to be welded, the planar metal surface and cylindrical metal surface thereby forming an acute angle of contact. A laser beam, produced, for example, by a Nd:YAG pulsed laser, is focused through the acute angle of contact at the juncture area to be welded, with the laser beam heating the juncture area to a welding temperature to cause welding to occur between the planar metal surface and the cylindrical metal surface. Both the planar metal surface and cylindrical metal surface are made from a reflective metal, including copper, copper alloys, stainless steel alloys, aluminum, and aluminum alloys.

Influence of Welding Process and Post Weld Heat Treatment on Microstructure and Pitting Corrosion Behavior of Dissimilar Aluminium Alloy Welds

NASA Astrophysics Data System (ADS)

Venkata Ramana, V. S. N.; Mohammed, Raffi; Madhusudhan Reddy, G.; Srinivasa Rao, K.

2018-03-01

Welding of dissimilar Aluminum alloy welds is becoming important in aerospace, shipbuilding and defence applications. In the present work, an attempt has been made to weld dissimilar aluminium alloys using conventional gas tungsten arc welding (GTAW) and friction stir welding (FSW) processes. An attempt was also made to study the effect of post weld heat treatment (T4 condition) on microstructure and pitting corrosion behaviour of these welds. Results of the present investigation established the differences in microstructures of the base metals in T4 condition and in annealed conditions. It is evident that the thickness of the PMZ is relatively more on AA2014 side than that of AA6061 side. In FS welds, lamellar like shear bands are well noticed on the top of the stir zone. The concentration profile of dissimilar friction stir weld in T4 condition revealed that no diffusion has taken place at the interface. Poor Hardness is observed in all regions of FS welds compared to that of GTA welds. Pitting corrosion resistance of the dissimilar FS welds in all regions was improved by post weld heat treatment.

Robotic Variable Polarity Plasma Arc (VPPA) Welding

NASA Technical Reports Server (NTRS)

Jaffery, Waris S.

1993-01-01

The need for automated plasma welding was identified in the early stages of the Space Station Freedom Program (SSFP) because it requires approximately 1.3 miles of welding for assembly. As a result of the Variable Polarity Plasma Arc Welding (VPPAW) process's ability to make virtually defect-free welds in aluminum, it was chosen to fulfill the welding needs. Space Station Freedom will be constructed of 2219 aluminum utilizing the computer controlled VPPAW process. The 'Node Radial Docking Port', with it's saddle shaped weld path, has a constantly changing surface angle over 360 deg of the 282 inch weld. The automated robotic VPPAW process requires eight-axes of motion (six-axes of robot and two-axes of positioner movement). The robot control system is programmed to maintain Torch Center Point (TCP) orientation perpendicular to the part while the part positioner is tilted and rotated to maintain the vertical up orientation as required by the VPPAW process. The combined speed of the robot and the positioner are integrated to maintain a constant speed between the part and the torch. A laser-based vision sensor system has also been integrated to track the seam and map the surface of the profile during welding.

Robotic Variable Polarity Plasma Arc (VPPA) welding

NASA Astrophysics Data System (ADS)

Jaffery, Waris S.

1993-02-01

The need for automated plasma welding was identified in the early stages of the Space Station Freedom Program (SSFP) because it requires approximately 1.3 miles of welding for assembly. As a result of the Variable Polarity Plasma Arc Welding (VPPAW) process's ability to make virtually defect-free welds in aluminum, it was chosen to fulfill the welding needs. Space Station Freedom will be constructed of 2219 aluminum utilizing the computer controlled VPPAW process. The 'Node Radial Docking Port', with it's saddle shaped weld path, has a constantly changing surface angle over 360 deg of the 282 inch weld. The automated robotic VPPAW process requires eight-axes of motion (six-axes of robot and two-axes of positioner movement). The robot control system is programmed to maintain Torch Center Point (TCP) orientation perpendicular to the part while the part positioner is tilted and rotated to maintain the vertical up orientation as required by the VPPAW process. The combined speed of the robot and the positioner are integrated to maintain a constant speed between the part and the torch. A laser-based vision sensor system has also been integrated to track the seam and map the surface of the profile during welding.

Microstructure and Mechanical Properties of Welds of Al - Mg - Si Alloys After Different Modes of Impulse Friction Stir Welding

NASA Astrophysics Data System (ADS)

Kondrat'ev, S. Yu.; Morozova, Yu. N.; Golubev, Yu. A.; Hantelmann, C.; Naumov, A. A.; Mikhailov, V. G.

2018-03-01

Welded joints of aluminum alloy 6082-T6 formed by the method of impulse friction stir welding are studied. The effect of the power and frequency of the pulses on the microstructure and mechanical properties of the welded joints is determined. Application of an additional pulse during the welding affects the surface quality and the shape of the weld, the distribution of the oxide layer and of particles of the hardening phase, and the grain size in the zone of dynamic recrystallization.

Mechanical Properties and Microstructural Evolution of Friction-Stir-Welded Thin Sheet Aluminum Alloys

NASA Astrophysics Data System (ADS)

Cerri, Emanuela; Leo, Paola; Wang, Xiang; Embury, J. D.

2011-05-01

Friction stir welding of thin aluminum sheets represents a potential goal for aircraft and automotive industries because of the advantages of using this new technological process. In the current work, the microstructural evolution and mechanical behavior of 6082T6-6082T6, 2024T3-2024T3, and 6082T6-2024T3 thin friction-stir-welded joints were investigated. Uniaxial tensile testing at room temperature, 443 K, 473 K, and 503 K (170 °C, 200 °C, and 230 °C) was used to determine the extent to which these ultra-thin joints can be used and deformed. The tensile stress-strain curves showed a decrease of the flow stress with increasing temperature and decreasing strain rate. The ductility of 6082T6-6082T6 joints generally improved when deformed at warm temperatures. It was almost constant for the 6082T6-2024T3 and reached the higher value in the 2024T3-2024T3 when deformed at 443 K and 473 K (170 °C and 200 °C) when compared with the room temperature value. Tensile specimens fractured in the middle of the weld zone in a ductile mode. The precipitation and growth of S' type phases strengthens 2024T3-2024T3 joints during deformation. In the 6082T6-6082T6, β″ precipitates show some increase in size but give a lower contribution to strength. At 503 K (230 °C), recovery mechanisms (dislocation reorganization inside the deformed grains) are initiated but the temperature was not enough high to produce a homogeneous subgrain structure.

Modelling of fluid flow phenomenon in laser+GMAW hybrid welding of aluminum alloy considering three phase coupling and arc plasma shear stress

NASA Astrophysics Data System (ADS)

Xu, Guoxiang; Li, Pengfei; Cao, Qingnan; Hu, Qingxian; Gu, Xiaoyan; Du, Baoshuai

2018-03-01

The present study aims to develop a unified three dimensional numerical model for fiber laser+GMAW hybrid welding, which is used to study the fluid flow phenomena in hybrid welding of aluminum alloy and the influence of laser power on weld pool dynamic behavior. This model takes into account the coupling of gas, liquid and metal phases. Laser heat input is described using a cone heat source model with changing peak power density, its height being determined based on the keyhole size. Arc heat input is modeled as a double ellipsoid heat source. The arc plasma flow and droplet transfer are simulated through the two simplified models. The temperature and velocity fields for different laser powers are calculated. The computed results are in general agreement with the experimental data. Both the peak and average values of fluid flow velocity during hybrid welding are much higher than those of GMAW. At a low level of laser power, both the arc force and droplet impingement force play a relatively large role on fluid flow in the hybrid welding. Keyhole depth always oscillates within a range. With an increase in laser power, the weld pool behavior becomes more complex. An anti-clockwise vortex is generated and the stability of keyhole depth is improved. Besides, the effects of laser power on different driving forces of fluid flow in weld pool are also discussed.

Interstitial pneumonitis after acetylene welding: a case report.

PubMed

Brvar, Miran

2014-01-01

Acetylene is a colorless gas commonly used for welding. It acts mainly as a simple asphyxiant. In this paper, however, we present a patient who developed a severe interstitial pneumonitis after acetylene exposure during aluminum welding. A 44-year old man was welding with acetylene, argon and aluminum electrode sticks in a non-ventilated aluminum tank for 2 h. Four hours after welding dyspnea appeared and 22 h later he was admitted at the Emergency Department due to severe respiratory insufficiency with pO2 = 6.7 kPa. Chest X-ray showed diffuse interstitial infiltration. Pulmonary function and gas diffusion tests revealed a severe restriction (55% of predictive volume) and impaired diffusion capacity (47% of predicted capacity). Toxic interstitial pneumonitis was diagnosed and high-dose systemic corticosteroid methylprednisolone and inhalatory corticosteroid fluticasone therapy was started. Computed Tomography (CT) of the lungs showed a diffuse patchy ground-glass opacity with no signs of small airway disease associated with interstitial pneumonitis. Corticosteroid therapy was continued for the next 8 weeks gradually reducing the doses. The patient's follow-up did not show any deterioration of respiratory function. In conclusion, acetylene welding might result in severe toxic interstitial pneumonitis that improves after an early systemic and inhalatory corticosteroid therapy.

Experimental and numerical studies on three dimensional GTA weld pool convection: Non-axisymmetric effects

DOE Office of Scientific and Technical Information (OSTI.GOV)

Joshi, Y.; Dutta, P.; Schupp, P.E.

1995-12-31

Observations of surface flow patterns of steel and aluminum GTAW pools have been made using a pulsed laser visualization system. The weld pool convection is found to be three dimensional, with the azimuthal circulation depending on the location of the clamp with respect to the torch. Oscillation of steel pools and undulating motion in aluminum weld pools are also observed even with steady process parameters. Current axisymmetric numerical models are unable to explain such phenomena. A three dimensional computational study is carried out in this study to explain the rotational flow in aluminum weld pools.

Effect of Repair Welding on Electrochemical Corrosion and Stress Corrosion Cracking Behavior of TIG Welded AA2219 Aluminum Alloy in 3.5 Wt Pct NaCl Solution

NASA Astrophysics Data System (ADS)

Venugopal, A.; Sreekumar, K.; Raja, V. S.

2010-12-01

The stress corrosion cracking (SCC) behavior of AA2219 aluminum alloy in the as-welded (AW) and repair-welded (RW) conditions was examined and compared with that of the base metal (BM) in 3.5 wt pct NaCl solution using the slow strain rate technique (SSRT). The reduction in ductility was used as a parameter to evaluate the SCC susceptibility of both BM and welded joints. The results show that the ductility ratio ( ɛ NaCl/( ɛ air)) of the BM was close to one (0.97) and reduced to 0.9 for the AW joint. This value further reduced to 0.77 after carrying out one repair welding operation. However, the RW specimen exhibited higher ductility than the single-weld specimens even in 3.5 wt pct NaCl solution. SSRT results obtained using pre-exposed samples followed by post-test metallographic observations clearly showed localized pitting corrosion along the partially melted zone (PMZ), signifying that the reduction in ductility ratio of both the AW and RW joints was more due to mechanical overload failure, caused by the localized corrosion and a consequent reduction in specimen thickness, than due to SCC. Also, the RW joint exhibited higher ductility than the AW joint both in air and the environment, although SCC index (SI) for the former is lower than that of the latter. Fractographic examination of the failed samples, in general, revealed a typical ductile cracking morphology for all the base and welded joints, indicating the good environmental cracking resistance of this alloy. Microstructural examination and polarization tests further demonstrate grain boundary melting along the PMZ, and that provided the necessary electrochemical condition for the preferential cracking on that zone of the weldment.

SLI Complex Curvature Friction Stir Weld Risk Reduction Program

NASA Technical Reports Server (NTRS)

Hartley, Paula J.; Schneider, Jules; Jones, Chip; Lawless, Kirby; Russell, Carolyn

2003-01-01

The Space Launch Initiative Program (SLI) in conjunction with the National Center for Advanced Manufacturing (NCAM) will demonstrate the ability to produce large-scale complex curvature hardware using the self-reacting friction stir welding process. This multi-phased risk reduction program includes friction stir welding process development and manufacture of a 22-ft diameter quarter dome using a conventional tooling approach; it culminates in a 27.5-ft diameter quarter dome demonstration performed on a 5-axis Universal Weld System. The design, fabrication, and installation of the Universal Weld System is made possible through a collaboration between the State of Louisiana, NASA, and the University of New Orleans. The Universal Weld System, manufactured by MTS Systems Corporation, will be installed at the Michoud Assembly Facility in New Orleans, Louisiana, and will be capable of manufacturing domes up to 30 ft in diameter. All welding will be accomplished using the Adaptable Adjustable Pin Tool (AdAPT) weld head and controller manufactured by MTS. Weld parameters will be developed for an aluminum alloy in gauges ranging from 0.320 to 0.400 in. thick. Weld quality will be verified through radiography, mechanical property testing at ambient and LN2 temperatures, and metallurgical analysis. The AdAPT weld head will then be mounted on a 22-ft diameter dome tool, which will be modified to include a welding track and drive system for moving the AdAPT weld head along the weld joint. This tool will then be used to manufacture a 22-ft diameter dome of an aluminum alloy, with 0.320-in. constant thickness joints, consisting of three individual gore panels. Finally, the 27.5-ft diameter quarter dome will be welded on the Universal Weld System. The quarter dome will consist of three individual gore panels with weld lands tapering from 0.320 to 0.360 in. in thickness. With the demonstration of these welds, the ability to manufacture large diameter domes using the friction stir

Effect of Steel Galvanization on the Microstructure and Mechanical Performances of Planar Magnetic Pulse Welds of Aluminum and Steel

NASA Astrophysics Data System (ADS)

Avettand-Fènoël, M.-N.; Khalil, C.; Taillard, R.; Racineux, G.

2018-07-01

For the first time, planar joints between pure aluminum and galvanized or uncoated DP450 steel joints have been developed via magnetic pulse welding. Both present a wavy interface. The microstructure of the interfacial zone differs according to the joint. With uncoated steel, the interface is composed of discrete 2.5- µm-thick FeAl3 intermetallic compounds and Fe penetration lamellae, whereas the interface of the pure Al-galvanized steel joint is bilayered and composed of a 10-nm-thick (Al)Zn solid solution and a few micrometers thick aggregate of Al- and Zn-based grains, arranged from the Al side to the Zn coating. Even if the nature of the interfacial zone differs with or without the steel coating, both welds present rather similar maximum tensile forces and ductility in shear lap testing.

Effect of Steel Galvanization on the Microstructure and Mechanical Performances of Planar Magnetic Pulse Welds of Aluminum and Steel

NASA Astrophysics Data System (ADS)

Avettand-Fènoël, M.-N.; Khalil, C.; Taillard, R.; Racineux, G.

2018-05-01

For the first time, planar joints between pure aluminum and galvanized or uncoated DP450 steel joints have been developed via magnetic pulse welding. Both present a wavy interface. The microstructure of the interfacial zone differs according to the joint. With uncoated steel, the interface is composed of discrete 2.5-µm-thick FeAl3 intermetallic compounds and Fe penetration lamellae, whereas the interface of the pure Al-galvanized steel joint is bilayered and composed of a 10-nm-thick (Al)Zn solid solution and a few micrometers thick aggregate of Al- and Zn-based grains, arranged from the Al side to the Zn coating. Even if the nature of the interfacial zone differs with or without the steel coating, both welds present rather similar maximum tensile forces and ductility in shear lap testing.

Effect of Traverse and Rotational Speeds on the Tensile Behavior of the Underwater Dissimilar Friction Stir Welded Aluminum Alloys

NASA Astrophysics Data System (ADS)

Bijanrostami, Kh.; Barenji, R. Vatankhah; Hashemipour, M.

2017-02-01

The tensile behavior of the underwater dissimilar friction stir welded AA6061 and AA7075 aluminum alloy joints was investigated for the first time. For this aim, the joints were welded at different conditions and tensile test was conducted for measuring the strength and elongation of them. In addition, the microstructure of the joints was characterized by means of optical and transmission electron microscopes. Scanning electron microscope was used for fractography of the joints. Furthermore, the process parameters and tensile properties of the joints were correlated and optimized. The results revealed that the maximum tensile strength of 237.3 MPa and elongation of 41.2% could be obtained at a rotational speed 1853 rpm and a traverse speed of 50 mm/min. In comparison with the optimum condition, higher heat inputs caused grain growth and reduction in dislocation density and hence led to lower strength. The higher elongations for the joints welded at higher heat inputs were due to lower dislocation density inside the grains, which was consistent with a more ductile fracture of them.

Nonchamber, Root-Side, Inert-Gas Purging During Welding

NASA Technical Reports Server (NTRS)

Mcgee, William F.; Rybicki, Daniel J.

1995-01-01

Improved apparatus distributes inert gas to protect against oxidation on root side of weld during welding and after welding while joint remains hot. Simple and lightweight; readily moved along weld path in synchronism with torch. Because it concentrates inert gas where needed, consumes gas at relatively low rate, and not necessary to monitor oxygen content of protective atmosphere. Apparatus does not obscure view of root side of weld. Used for full-penetration plasma-arc welding of such reactive metals as aluminum/lithium alloys and titanium.

Damage Tolerance Behavior of Friction Stir Welds in Aluminum Alloys

NASA Technical Reports Server (NTRS)

McGill, Preston; Burkholder, Jonathan

2012-01-01

Friction stir welding is a solid state welding process used in the fabrication of various aerospace structures. Self-reacting and conventional friction stir welding are variations of the friction stir weld process employed in the fabrication of cryogenic propellant tanks which are classified as pressurized structure in many spaceflight vehicle architectures. In order to address damage tolerance behavior associated with friction stir welds in these safety critical structures, nondestructive inspection and proof testing may be required to screen hardware for mission critical defects. The efficacy of the nondestructive evaluation or the proof test is based on an assessment of the critical flaw size. Test data describing fracture behavior, residual strength capability, and cyclic mission life capability of friction stir welds at ambient and cryogenic temperatures have been generated and will be presented in this paper. Fracture behavior will include fracture toughness and tearing (R-curve) response of the friction stir welds. Residual strength behavior will include an evaluation of the effects of lack of penetration on conventional friction stir welds, the effects of internal defects (wormholes) on self-reacting friction stir welds, and an evaluation of the effects of fatigue cycled surface cracks on both conventional and selfreacting welds. Cyclic mission life capability will demonstrate the effects of surface crack defects on service load cycle capability. The fracture data will be used to evaluate nondestructive inspection and proof test requirements for the welds.

Mechanical Properties of Aluminum-Based Dissimilar Alloy Joints by Power Beams, Arc and FSW Processes

NASA Astrophysics Data System (ADS)

Okubo, Michinori; Kon, Tomokuni; Abe, Nobuyuki

Dissimilar smart joints are useful. In this research, welded quality of dissimilar aluminum alloys of 3 mm thickness by various welding processes and process parameters have been investigated by hardness and tensile tests, and observation of imperfection and microstructure. Base metals used in this study are A1050-H24, A2017-T3, A5083-O, A6061-T6 and A7075-T651. Welding processes used are YAG laser beam, electron beam, metal inert gas arc, tungsten inert gas arc and friction stir welding. The properties of weld zones are affected by welding processes, welding parameters and combination of base metals. Properties of high strength aluminum alloy joints are improved by friction stir welding.

Thermographic Analysis of Stress Distribution in Welded Joints

NASA Astrophysics Data System (ADS)

Piršić, T.; Krstulović Opara, L.; Domazet, Ž.

2010-06-01

The fatigue life prediction of welded joints based on S-N curves in conjunction with nominal stresses generally is not reliable. Stress distribution in welded area affected by geometrical inhomogeneity, irregular welded surface and weld toe radius is quite complex, so the local (structural) stress concept is accepted in recent papers. The aim of this paper is to determine the stress distribution in plate type aluminum welded joints, to analyze the reliability of TSA (Thermal Stress Analysis) in this kind of investigations, and to obtain numerical values for stress concentration factors for practical use. Stress distribution in aluminum butt and fillet welded joints is determined by using the three different methods: strain gauges measurement, thermal stress analysis and FEM. Obtained results show good agreement - the TSA mutually confirmed the FEM model and stresses measured by strain gauges. According to obtained results, it may be stated that TSA, as a relatively new measurement technique may in the future become a standard tool for the experimental investigation of stress concentration and fatigue in welded joints that can help to develop more accurate numerical tools for fatigue life prediction.

FORMATION MECHANISM FOR THE NANOSCALE AMORPHOUS INTERFACE IN PULSE-WELDED AL/FE BIMETALLIC SYSTEM

DOE PAGES

Li, Jingjing; Yu, Qian; Zhang, Zijiao; ...

2016-05-20

Pulse or impact welding traditionally has been referred to as “solid-state” welding. By integrating advanced interface characterizations and diffusion calculations, we report that the nanoscale amorphous interface in the pulse-welded Al/Fe bimetallic system is formed by rapid heating and melting of a thin Al layer at the interface, diffusion of iron atoms in the liquid aluminum, and subsequent rapid quenching with diffused iron atoms in solution. This finding challenges the commonly held belief regarding the solid-state nature of the impact-based welding process for dissimilar metals. Elongated ultra-fine grains with high dislocation density and ultra-fine equiaxed grains also are observed inmore » the weld interface vicinity on the steel and aluminum sides, respectively, which further confirms that melting and the resulted recrystallization occurred on the aluminum side of the interface.« less

FORMATION MECHANISM FOR THE NANOSCALE AMORPHOUS INTERFACE IN PULSE-WELDED AL/FE BIMETALLIC SYSTEM

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Jingjing; Yu, Qian; Zhang, Zijiao

Pulse or impact welding traditionally has been referred to as “solid-state” welding. By integrating advanced interface characterizations and diffusion calculations, we report that the nanoscale amorphous interface in the pulse-welded Al/Fe bimetallic system is formed by rapid heating and melting of a thin Al layer at the interface, diffusion of iron atoms in the liquid aluminum, and subsequent rapid quenching with diffused iron atoms in solution. This finding challenges the commonly held belief regarding the solid-state nature of the impact-based welding process for dissimilar metals. Elongated ultra-fine grains with high dislocation density and ultra-fine equiaxed grains also are observed inmore » the weld interface vicinity on the steel and aluminum sides, respectively, which further confirms that melting and the resulted recrystallization occurred on the aluminum side of the interface.« less

Formation mechanism for the nanoscale amorphous interface in pulse-welded Al/Fe bimetallic systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Jingjing; Yu, Qian; Zhang, Zijiao

Pulse or impact welding traditionally has been referred to as “solid-state” welding. By integrating advanced interface characterizations and diffusion calculations, we report that the nanoscale amorphous interface in the pulse-welded Al/Fe bimetallic system is formed by rapid heating and melting of a thin Al layer at the interface, diffusion of iron atoms in the liquid aluminum, and subsequent rapid quenching with diffused iron atoms in solution. This finding challenges the commonly held belief regarding the solid-state nature of the impact-based welding process for dissimilar metals. Elongated ultra-fine grains with high dislocation density and ultra-fine equiaxed grains also are observed inmore » the weld interface vicinity on the steel and aluminum sides, respectively, which further confirms that melting and the subsequent recrystallization occurred on the aluminum side of the interface.« less

Melting Efficiency During Plasma Arc Welding

NASA Technical Reports Server (NTRS)

McClure, J.C.; Evans, D. M.; Tang, W.; Nunes, A. C.

1999-01-01

A series of partial penetration Variable Polarity Plasma Arc welds were made at equal power but various combinations of current and voltage on 2219 aluminum. Arc Efficiency was measured calorimetrically and ranged between 48% and 66%. Melting efficiency depends on the weld pool shape. Increased current increases the melting efficiency as it increases the depth to width ratio of the weld pool. Higher currents are thought to raise arc pressure and depress the liquid at the bottom of the weld pool causing a more nearly two dimensional heat flow condition.

A study of mechanical properties for aluminum GMA weldments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kluken, A.O.; Bjoerneklett, B.

1997-02-01

Medium- to high-strength aluminum alloys represent an attractive alternative to steel as a material for critical structural members. One area of great interest for their use is the transportation industry due to the increasing demands for less environmental impact through improved fuel efficiency, weight reductions, and increased load capacity. Fabrication of structural bodies involves, in most instances, the application of a joining process. Load-carrying members must be joined together or nonload-carrying parts attached to the primary structure. Although adhesive bonding, laser beam welding and friction stir welding are attractive processes for joining of aluminum, gas metal arc welding (GMAW) ismore » by far the most widely used process at present. Fusion welding of a heat-treatable aluminum alloy represents an additional local heat treatment of material that previously has been processed through tight temperature control to obtain the desired mechanical properties. Hence, great attention must be given to selection of alloy and temper condition, welding parameters, and postweld aging procedures for a given application. The objective of this investigation was to establish mechanical property data, i.e., tensile strength and impact toughness, for Al-Mg-Si and Al-Zn-Mg gas metal arc weldments applicable to the automotive and shipbuilding industries.« less

Evaluation of Surface Roughness by Image Processing of a Shot-Peened, TIG-Welded Aluminum 6061-T6 Alloy: An Experimental Case Study

PubMed Central

Rawashdeh, Nathir A.

2018-01-01

Visual inspection through image processing of welding and shot-peened surfaces is necessary to overcome equipment limitations, avoid measurement errors, and accelerate processing to gain certain surface properties such as surface roughness. Therefore, it is important to design an algorithm to quantify surface properties, which enables us to overcome the aforementioned limitations. In this study, a proposed systematic algorithm is utilized to generate and compare the surface roughness of Tungsten Inert Gas (TIG) welded aluminum 6061-T6 alloy treated by two levels of shot-peening, high-intensity and low-intensity. This project is industrial in nature, and the proposed solution was originally requested by local industry to overcome equipment capabilities and limitations. In particular, surface roughness measurements are usually only possible on flat surfaces but not on other areas treated by shot-peening after welding, as in the heat-affected zone and weld beads. Therefore, those critical areas are outside of the measurement limitations. Using the proposed technique, the surface roughness measurements were possible to obtain for weld beads, high-intensity and low-intensity shot-peened surfaces. In addition, a 3D surface topography was generated and dimple size distributions were calculated for the three tested scenarios: control sample (TIG-welded only), high-intensity shot-peened, and low-intensity shot-peened TIG-welded Al6065-T6 samples. Finally, cross-sectional hardness profiles were measured for the three scenarios; in all scenarios, lower hardness measurements were obtained compared to the base metal alloy in the heat-affected zone and in the weld beads even after shot-peening treatments. PMID:29748520

Evaluation of Surface Roughness by Image Processing of a Shot-Peened, TIG-Welded Aluminum 6061-T6 Alloy: An Experimental Case Study.

PubMed

Atieh, Anas M; Rawashdeh, Nathir A; AlHazaa, Abdulaziz N

2018-05-10

Visual inspection through image processing of welding and shot-peened surfaces is necessary to overcome equipment limitations, avoid measurement errors, and accelerate processing to gain certain surface properties such as surface roughness. Therefore, it is important to design an algorithm to quantify surface properties, which enables us to overcome the aforementioned limitations. In this study, a proposed systematic algorithm is utilized to generate and compare the surface roughness of Tungsten Inert Gas (TIG) welded aluminum 6061-T6 alloy treated by two levels of shot-peening, high-intensity and low-intensity. This project is industrial in nature, and the proposed solution was originally requested by local industry to overcome equipment capabilities and limitations. In particular, surface roughness measurements are usually only possible on flat surfaces but not on other areas treated by shot-peening after welding, as in the heat-affected zone and weld beads. Therefore, those critical areas are outside of the measurement limitations. Using the proposed technique, the surface roughness measurements were possible to obtain for weld beads, high-intensity and low-intensity shot-peened surfaces. In addition, a 3D surface topography was generated and dimple size distributions were calculated for the three tested scenarios: control sample (TIG-welded only), high-intensity shot-peened, and low-intensity shot-peened TIG-welded Al6065-T6 samples. Finally, cross-sectional hardness profiles were measured for the three scenarios; in all scenarios, lower hardness measurements were obtained compared to the base metal alloy in the heat-affected zone and in the weld beads even after shot-peening treatments.

Vaccum Gas Tungsten Arc Welding, phase 1

NASA Astrophysics Data System (ADS)

Weeks, J. L.; Krotz, P. D.; Todd, D. T.; Liaw, Y. K.

1995-03-01

This two year program will investigate Vacuum Gas Tungsten Arc Welding (VGTAW) as a method to modify or improve the weldability of normally difficult-to-weld materials. VGTAW appears to offer a significant improvement in weldability because of the clean environment and lower heat input needed. The overall objective of the program is to develop the VGTAW technology and implement it into a manufacturing environment that will result in lower cost, better quality and higher reliability aerospace components for the space shuttle and other NASA space systems. Phase 1 of this program was aimed at demonstrating the process's ability to weld normally difficult-to-weld materials. Phase 2 will focus on further evaluation, a hardware demonstration and a plan to implement VGTAW technology into a manufacturing environment. During Phase 1, the following tasks were performed: (1) Task 11000 Facility Modification - an existing vacuum chamber was modified and adapted to a GTAW power supply; (2) Task 12000 Materials Selection - four difficult-to-weld materials typically used in the construction of aerospace hardware were chosen for study; (3) Task 13000 VGTAW Experiments - welding experiments were conducted under vacuum using the hollow tungsten electrode and evaluation. As a result of this effort, two materials, NARloy Z and Incoloy 903, were downselected for further characterization in Phase 2; and (4) Task 13100 Aluminum-Lithium Weld Studies - this task was added to the original work statement to investigate the effects of vacuum welding and weld pool vibration on aluminum-lithium alloys.

Vaccum Gas Tungsten Arc Welding, phase 1

NASA Technical Reports Server (NTRS)

Weeks, J. L.; Krotz, P. D.; Todd, D. T.; Liaw, Y. K.

1995-01-01

This two year program will investigate Vacuum Gas Tungsten Arc Welding (VGTAW) as a method to modify or improve the weldability of normally difficult-to-weld materials. VGTAW appears to offer a significant improvement in weldability because of the clean environment and lower heat input needed. The overall objective of the program is to develop the VGTAW technology and implement it into a manufacturing environment that will result in lower cost, better quality and higher reliability aerospace components for the space shuttle and other NASA space systems. Phase 1 of this program was aimed at demonstrating the process's ability to weld normally difficult-to-weld materials. Phase 2 will focus on further evaluation, a hardware demonstration and a plan to implement VGTAW technology into a manufacturing environment. During Phase 1, the following tasks were performed: (1) Task 11000 Facility Modification - an existing vacuum chamber was modified and adapted to a GTAW power supply; (2) Task 12000 Materials Selection - four difficult-to-weld materials typically used in the construction of aerospace hardware were chosen for study; (3) Task 13000 VGTAW Experiments - welding experiments were conducted under vacuum using the hollow tungsten electrode and evaluation. As a result of this effort, two materials, NARloy Z and Incoloy 903, were downselected for further characterization in Phase 2; and (4) Task 13100 Aluminum-Lithium Weld Studies - this task was added to the original work statement to investigate the effects of vacuum welding and weld pool vibration on aluminum-lithium alloys.

Safety Grooving

NASA Technical Reports Server (NTRS)

1985-01-01

Safety grooving, the cutting of grooves in concrete to increase traction and prevent injury, was first developed to reduce aircraft accidents on wet runways. Represented by the International Grooving and Grinding Association (IG&GA), the industry expanded into highway and pedestrian applications. The technique originated at Langley, which assisted in testing the grooving at airports and on highways. Skidding was reduced, stopping distance decreased, and a vehicle's cornering ability on curves was increased. The process has been extended to animal holding pens, steps, parking lots and other potentially slippery surfaces.

Effect of rotation speed and welding speed on Friction Stir Welding of AA1100 Aluminium alloy

NASA Astrophysics Data System (ADS)

Raja, P.; Bojanampati, S.; Karthikeyan, R.; Ganithi, R.

2018-04-01

Aluminum AA1100 is the most widely used grade of Aluminium due to its excellent corrosion resistance, high ductility and reflective finish, the selected material was welded with Friction Stir Welding (FSW) process on a CNC machine, using a combination of different tool rotation speed (1500 rpm, 2500 rpm, 3500 rpm) and welding speed (10 mm/min, 30 mm/min, 50 mm/min) as welding parameters. The effect of FSW using this welding parameter was studied by measuring the ultimate tensile strength of the welded joints. A high-speed steel tool was prepared for welding the Aluminium AA1100 alloy having an 8mm shoulder diameter and pin dimension of 4mm diameter and 2.8 mm length. The welded joints were tested using the universal testing machine. It was found that Ultimate Tensile Strength of FSW specimen was highest with a value of 98.08 MPa when the weld was performed at rotation speed of 1500 RPM and welding speed of 50 mm/min.

Computer Tomography 3-D Imaging of the Metal Deformation Flow Path in Friction Stir Welding

NASA Technical Reports Server (NTRS)

Schneider, Judy; Beshears, Ronald; Nunes, Arthur C., Jr.

2004-01-01

In friction stir welding, a rotating threaded pin tool is inserted into a weld seam and literally stirs the edges of the seam together. This solid-state technique has been successfully used in the joining of materials that are difficult to fusion weld such as aluminum alloys. To determine optimal processing parameters for producing a defect free weld, a better understanding of the resulting metal deformation flow path is required. Marker studies are the principal method of studying the metal deformation flow path around the FSW pin tool. In our study, we have used computed tomography (CT) scans to reveal the flow pattern of a lead wire embedded in a FSW weld seam. At the welding temperature of aluminum, the lead becomes molten and thus tracks the aluminum deformation flow paths in a unique 3-dimensional manner. CT scanning is a convenient and comprehensive way of collecting and displaying tracer data. It marks an advance over previous more tedious and ambiguous radiographic/metallographic data collection methods.

Loading Considerations for Implementing Friction STIR Welding for Large Diameter Tank Fabrication

NASA Technical Reports Server (NTRS)

Adams, Glynn

1998-01-01

The main objectives of the research presented here are to determine the reaction loads associated with friction stir welding (FSW) and to determine the suitability of an existing welding fixture for implementing this welding process in the fabrication of large diameter tanks. Friction stir welding is a relatively new process which is being investigated as a method for joining aluminum alloys. The aluminum-lithium alloy, Al-Li 2195, which is being used to fabricate the super-light-weight shuttle external tank has proven difficult to join using fusion techniques. Therefore, FSW and its potential applicability to joining Al-Li 2195 are of particular interest to NASA.

73rd American Welding Society annual meeting

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1992-01-01

The volume includes the abstracts of papers presented at the 73rd American Welding Society Annual Meeting. Detailed summaries are given for 118 technical sessions papers discussing computer and control applications in welding, stainless steel, nickel and nickel alloys, weld metal microstructure, shipbuilding, consumables, structural welding, investigations in arc welding and cutting, arc welding processes, weldability testing, piping and tubing, high energy beam welding processes, welding metallurgy of structural steels, new applications, weld metal behavior, NDT certification, aluminum welding, submerged arc welding, modeling studies, resistance welding, friction welding, and safety and health. The 23rd International AWS Brazing and Soldering Conference wasmore » also held during this meeting. The topics presented in 24 papers included recent developments in soldering technology, brazing of stainless steel, brazing of ceramics and nickel material, filler metal developments for torch brazing, and developments in diffusion and induction brazing.« less

Application of Pre-heating to Improve the Consistency and Quality in AA5052 Resistance Spot Welding

NASA Astrophysics Data System (ADS)

Luo, Zhen; Ao, Sansan; Chao, Yuh Jin; Cui, Xuetuan; Li, Yang; Lin, Ye

2015-10-01

Making consistent resistance spot welds of aluminum alloy with good quality and at high volume has several obstacles in automotive industry. One of the difficult issues arises from the presence of a tough non-conducting oxide film on the aluminum sheet surface. The oxide film develops over time and often is non-uniform across the surface of the aluminum alloy sheet, which makes the contact resistance characteristics irregular at the faying interface during welding. The consistency in quality of the final spot welds is therefore problematic to control. To suppress the effect of the irregular oxide film on the spot weld quality, application of a pre-heating treatment in the welding schedule for aluminum alloy 5052 is investigated in this present work. The current level of the pre-heating required to reduce the scatter of the contact resistance at the W/W (workpiece-to-workpiece) faying interface is quantified experimentally. The results indicate that the contact resistance at the W/W faying interface with a pre-heating treatment becomes much consistent and can be reduced by two orders of magnitude. Having the uncertain variation of the contact resistance at the W/W faying surface virtually reduced or removed, the quality of the spot welds in terms of the peak load and nugget diameter is examined and shows a great improvement. The proposed method may provide a robust method for high-volume spot welding of aluminum alloy sheets in auto industry.

Automatic weld torch guidance control system

NASA Technical Reports Server (NTRS)

Smaith, H. E.; Wall, W. A.; Burns, M. R., Jr.

1982-01-01

A highly reliable, fully digital, closed circuit television optical, type automatic weld seam tracking control system was developed. This automatic tracking equipment is used to reduce weld tooling costs and increase overall automatic welding reliability. The system utilizes a charge injection device digital camera which as 60,512 inidividual pixels as the light sensing elements. Through conventional scanning means, each pixel in the focal plane is sequentially scanned, the light level signal digitized, and an 8-bit word transmitted to scratch pad memory. From memory, the microprocessor performs an analysis of the digital signal and computes the tracking error. Lastly, the corrective signal is transmitted to a cross seam actuator digital drive motor controller to complete the closed loop, feedback, tracking system. This weld seam tracking control system is capable of a tracking accuracy of + or - 0.2 mm, or better. As configured, the system is applicable to square butt, V-groove, and lap joint weldments.

Structure and phase composition of welded joints modified by different welding techniques

NASA Astrophysics Data System (ADS)

Smirnov, Aleksander; Popova, Natalya; Nikonenko, Elena; Ozhiganov, Eugeniy; Ababkov, Nikolay; Koneva, Nina

2017-12-01

The paper presents the results of transmission electron microscopy (TEM) during the study of structure and phase composition of heat-affected zone (HAZ) of welded joints modified via four welding techniques, namely: electrode welding and electropercussive welding both with and without artificial flaws. The artificial flows represent aluminum pieces. TEM studies are carried out within the heat-affected zone, i.e. between the deposited and base metal, at 0.5 mm distance to the former. The 0.09C-2Mn-1Si-Fe steel type is used for welding. It is shown how the type of welding affects steel morphology, phase composition, defect structure and its parameters. The type of carbide phase is detected as well as the shape and location of particles. Volume fractions are estimated for the structural steel components, alongside with such parameters as the size of α-phase fragments, scalar and excess dislocation densities, and bending-torsion amplitude of the crystal lattice. Based on these results, we determine the welding technique and the structural component thus launching a mechanism of microcrack nucleation.

Welding Penetration Control of Fixed Pipe in TIG Welding Using Fuzzy Inference System

NASA Astrophysics Data System (ADS)

Baskoro, Ario Sunar; Kabutomori, Masashi; Suga, Yasuo

This paper presents a study on welding penetration control of fixed pipe in Tungsten Inert Gas (TIG) welding using fuzzy inference system. The welding penetration control is essential to the production quality welds with a specified geometry. For pipe welding using constant arc current and welding speed, the bead width becomes wider as the circumferential welding of small diameter pipes progresses. Having welded pipe in fixed position, obviously, the excessive arc current yields burn through of metals; in contrary, insufficient arc current produces imperfect welding. In order to avoid these errors and to obtain the uniform weld bead over the entire circumference of the pipe, the welding conditions should be controlled as the welding proceeds. This research studies the intelligent welding process of aluminum alloy pipe 6063S-T5 in fixed position using the AC welding machine. The monitoring system used a charge-coupled device (CCD) camera to monitor backside image of molten pool. The captured image was processed to recognize the edge of molten pool by image processing algorithm. Simulation of welding control using fuzzy inference system was constructed to simulate the welding control process. The simulation result shows that fuzzy controller was suitable for controlling the welding speed and appropriate to be implemented into the welding system. A series of experiments was conducted to evaluate the performance of the fuzzy controller. The experimental results show the effectiveness of the control system that is confirmed by sound welds.

Analysis of thermal stresses and metal movement during welding

NASA Technical Reports Server (NTRS)

Muraki, T.; Pattee, F. M.; Masubuchi, K.

1974-01-01

Finite element computer programs were developed to determine thermal stresses and metal movement during butt welding of flat plates and bead-on-plate welding along the girth of a cylindrical shell. Circular cylindrical shells of 6061 aluminum alloy were used for the tests. Measurements were made of changes in temperature and thermal strains during the welding process.

Atomic-scale bonding of bulk metallic glass to crystalline aluminum

NASA Astrophysics Data System (ADS)

Liu, K. X.; Liu, W. D.; Wang, J. T.; Yan, H. H.; Li, X. J.; Huang, Y. J.; Wei, X. S.; Shen, J.

2008-08-01

A Ti40Zr25Cu12Ni3Be20 bulk metallic glass (BMG) was welded to a crystalline aluminum by the parallel plate explosive welding method. Experimental evidence and numerical simulation show that atomic-scale bonding between the BMG and the crystalline aluminum can be achieved, and the weldment on the BMG side can retain its amorphous state without any indication of crystallization in the welding process. Nanoindentation tests reveal that the interface of the explosive joints exhibits a significant increase in hardness compared to the matrix on its two sides. The joining of BMG and crystalline materials opens a window to the applications of BMGs in engineering.

Novel Method of Aluminum to Copper Bonding by Cold Spray

NASA Astrophysics Data System (ADS)

Fu, Si-Lin; Li, Cheng-Xin; Wei, Ying-Kang; Luo, Xiao-Tao; Yang, Guan-Jun; Li, Chang-Jiu; Li, Jing-Long

2018-04-01

Cold spray bonding (CSB) has been proposed as a new method for joining aluminum and copper. At high speeds, solid Al particles impacted the groove between the two substrates to form a bond between Al and Cu. Compared to traditional welding technologies, CSB does not form distinct intermetallic compounds. Large stainless steel particles were introduced into the spray powders as in situ shot peen particles to create a dense Al deposit and to improve the bond strength of joints. It was discovered that introducing shot peen particles significantly improved the flattening ratio of the deposited Al particles. Increasing the proportion of shot peen particles from 0 to 70 vol.% decreased the porosity of the deposits from 12.4 to 0.2%, while the shear strength of joints significantly increased. The tensile test results of the Al-Cu joints demonstrated that cracks were initiated at the interface between the Al and the deposit. The average tensile strength was 71.4 MPa and could reach 81% of the tensile strength of pure Al.

Improving Joint Formation and Tensile Properties of Dissimilar Friction Stir Welding of Aluminum and Magnesium Alloys by Solving the Pin Adhesion Problem

NASA Astrophysics Data System (ADS)

Liu, Zhenlei; Ji, Shude; Meng, Xiangchen

2018-03-01

Friction stir welding (FSW), as a solid-state welding technology invented by TWI in 1991, has potential to join dissimilar Al/Mg alloys. In this study, the pin adhesion phenomenon affecting joint quality during FSW of 6061-T6 aluminum and AZ31B magnesium alloys was investigated. The adhesion phenomenon induced by higher heat input easily transformed the tapered-and-screwed pin into a tapered pin, which greatly reduced the tool's ability to drive the plasticized materials and further deteriorated joint formation. Under the condition without the pin adhesion, the complex intercalated interlayer at the bottom of stir zone was beneficial to mechanical interlocking of Al/Mg alloys, improving tensile properties. However, the formation of intermetallic compounds was still the main reason of the joint fracture, significantly deteriorating tensile properties. Under the welding speed of 60 mm/min without the pin adhesion phenomenon, the maximum tensile strength of 107 MPa and elongation of 1.2% were achieved.

Effect of composition on the tensile properties and fracture toughness of A7N01S-T5 aluminum alloys welded joints

NASA Astrophysics Data System (ADS)

Liu, Yali; Gou, Guoqing; Chen, Jia; Chen, Hui; Wang, Wanjng; Li, Xiaodong; Che, Xiaoli; Wang, Yirong

2017-07-01

In this paper, welded joints of four types of A7N01S-T5 aluminum alloy with different chemical compositions were investigated. The welding process was under 70% environmental humidity conditions at 10∘C with single-pulse GMAW welding technology. The strength and fracture toughness of the four types of samples were tested, and the microstructures were investigated by micro-X-ray fluorescence (SR-LXRF) technology and backscattered electron diffraction (EBSD) technology. The results showed that the #2 alloy that is composed of Zn: 4.59 wt.%, Mg: 1.56 wt.% Mn: 0.22 wt.%, Cr: 0.14 wt.%, Zr: 0.01 wt.% and Ti: 0.027 wt.% had the best combination of tensile strength and elongation, with the values of 302.35 MPa and 3.74%, respectively. The better result for the combination of the strength and elongation was mainly determined by the volume fraction and size. The fine grain size and compositions played important roles to obtain high fracture toughness.

Microstructural analysis of the 2195 aluminum-lithium alloy welds

NASA Technical Reports Server (NTRS)

Talia, George E.

1993-01-01

The principal objective of this research was to explain a tendency of 2195 Al-Li alloy to crack at elevated temperature during welding. Therefore, a study was made on the effect of welding and thermal treatment on the microstructure of Al-Li Alloy 2195. The critical roles of precipitates, boundaries, phases, and other features of the microstructure were inferred from the crack propagation paths and the morphology of fracture surface of the alloy with different microstructures. Particular emphasis was placed on the microstructures generated by the welding process and the mechanisms of crack propagation in such structures. Variation of the welding parameters and thermal treatments were used to alter the micro/macro structures, and they were characterized by optical and scanning electron microscopy. A theoretical model is proposed to explain changes in the microstructure of welded material. This model proposes a chemical reaction in which gases from the air (i.e., nitrogen) release hydrogen inside the alloy. Such a reaction could generate large internal stresses capable to induce porosity and crack-like delamination in the material.

Building the Material Flow Networks of Aluminum in the 2007 U.S. Economy.

PubMed

Chen, Wei-Qiang; Graedel, T E; Nuss, Philip; Ohno, Hajime

2016-04-05

Based on the combination of the U.S. economic input-output table and the stocks and flows framework for characterizing anthropogenic metal cycles, this study presents a methodology for building material flow networks of bulk metals in the U.S. economy and applies it to aluminum. The results, which we term the Input-Output Material Flow Networks (IO-MFNs), achieve a complete picture of aluminum flow in the entire U.S. economy and for any chosen industrial sector (illustrated for the Automobile Manufacturing sector). The results are compared with information from our former study on U.S. aluminum stocks and flows to demonstrate the robustness and value of this new methodology. We find that the IO-MFN approach has the following advantages: (1) it helps to uncover the network of material flows in the manufacturing stage in the life cycle of metals; (2) it provides a method that may be less time-consuming but more complete and accurate in estimating new scrap generation, process loss, domestic final demand, and trade of final products of metals, than existing material flow analysis approaches; and, most importantly, (3) it enables the analysis of the material flows of metals in the U.S. economy from a network perspective, rather than merely that of a life cycle chain.

Laser-based welding of 17-4 PH martensitic stainless steel in a tubular butt joint configuration with a built-in backing bar

NASA Astrophysics Data System (ADS)

Ma, Junjie; Atabaki, Mehdi Mazar; Liu, Wei; Pillai, Raju; Kumar, Biju; Vasudevan, Unnikrishnan; Kovacevic, Radovan

2016-08-01

Laser-based welding of thick 17-4 precipitation hardening (PH) martensitic stainless steel (SS) plates in a tubular butt joint configuration with a built-in backing bar is very challenging because the porosity and cracks are easily generated in the welds. The backing bar blocked the keyhole opening at the bottom surface through which the entrapped gas could escape, and the keyhole was unstable and collapsed overtime in a deep partially penetrated welding conditions resulting in the formation of pores easily. Moreover, the fast cooling rate prompted the ferrite transform to austenite which induced cracking. Two-pass welding procedure was developed to join 17-4 PH martensitic SS. The laser welding assisted by a filler wire, as the first pass, was used to weld the groove shoulder. The added filler wire could absorb a part of the laser beam energy; resulting in the decreased weld depth-to-width ratio and relieved intensive restraint at the weld root. A hybrid laser-arc welding or a gas metal arc welding (GMAW) was used to fill the groove as the second pass. Nitrogen was introduced to stabilize the keyhole and mitigate the porosity. Preheating was used to decrease the cooling rate and mitigate the cracking during laser-based welding of 17-4 PH martensitic SS plates.

Assessment of the Sensitivity of Welded Joints of Al -Mg - Si Alloys to Liquation Cracks Under Laser Welding

NASA Astrophysics Data System (ADS)

Ivanov, S. Yu.; Karkhin, V. A.; Mikhailov, V. G.; Martikainen, J.; Hiltunen, E.

2018-03-01

The microstructure and the distribution of chemical elements in laser-welded joints of Al - Mg - Si alloy 6005-T6 are studied. Segregations of chemical elements are detected over grain boundaries in the heat-affected zones of the welded joints. The joints fracture by the intergrain mechanism. A Gleeble 3800 device is used to determine the temperature dependences of the mechanical properties of the alloy with allowance for the special features of the welding cycle. Amethod for evaluating the sensitivity of welded joints of aluminum alloys to formation of liquation cracks with allowance for the local properties of the metal, the welding conditions, and the rigidity of the construction is suggested.

Effect of friction stir welding parameters on defect formation

NASA Astrophysics Data System (ADS)

Tarasov, S. Yu.; Rubtsov, V. E.; Eliseev, A. A.; Kolubaev, E. A.; Filippov, A. V.; Ivanov, A. N.

2015-10-01

Friction stir welding is a perspective method for manufacturing automotive parts, aviation and space technology. One of the major problems is the formation of welding defects and weld around the welding zone. The formation of defect is the main reason failure of the joint. A possible way to obtain defect-free welded joints is the selection of the correct welding parameters. Experimental results describing the effect of friction stir welding process parameters on the defects of welded joints on aluminum alloy AMg5M have been shown. The weld joint defects have been characterized using the non-destructive radioscopic and ultrasound phase array methods. It was shown how the type and size of defects determine the welded joint strength.

Aluminum Lithium Alloy 2195 Fusion Welding Improvements with New Filler Wire

NASA Technical Reports Server (NTRS)

Russell, C.

2001-01-01

The objective of this research was to assess the B218 weld filler wire for Super Lightweight External Tank production, which could improve current production welding and repair productivity. We took the following approaches: (1) Perform a repair weld quick look evaluation between 4043/B218 and B218/B218 weld filler wire combinations and evaluation tensile properties for planished and unplanished conditions; and (2) Perform repair weld evaluation on structural simulation panel using 4043-B218 and B218/B218 weld filler wire combinations and evaluation tensile and simulated service fracture properties for planished and unplanished conditions.

Aluminum automotive space frames

DOE Office of Scientific and Technical Information (OSTI.GOV)

NONE

1995-08-01

Design of aluminum structures is to a new topic. Aircraft makers have successfully solved difficult structural problems with a high degree of understanding and reliability. Other transportation modes such as trucks, trailers, and railcars have faced structural problems with some emphasis on high- and low-cycle fatigue of welded aluminum structures. However, the automotive market places stringent engineering demands on materials and superimposes demanding cost constraints. A project was instituted at Reynolds Metals Co. to investigate the opportunities for the cost-effective application of aluminum to automotive spaceframes. Several areas were recognized as key to the success of this application. They were:more » equivalent or superior structural stiffness of the assembly to existing steel unibody and/or steel spaceframe vehicles; effective joining of spaceframe members; equivalent or superior crashworthiness of the assembly; weight savings; flexibility; and low-cost approach aimed at effective manufacturing. To gain experience with the key aspects in a practical environment, the experience of current builders of steel tube frame chassis was explored. These chassis are typically used in low-volume vehicles requiring torsional stiffness, excellent crashworthiness, and exterior body-style flexibility. A model was developed using finite element methods that accurately predicts mass and stiffness of frames. An effective aluminum space frame was generated which was 7.5% stiffer and more than 20% lighter than the steel frame, with stresses kept below the fatigue limit for aluminum welds.« less

Friction Stir Welding Development at NASA, Marshall Space Flight Center

NASA Technical Reports Server (NTRS)

McGill, Preston; Gentz, Steve (Technical Monitor)

2001-01-01

Friction stir welding (FSW) is a solid state process that pan be used to join materials without melting. The process was invented by The Welding Institute (TWI), Cambridge, England. Friction stir welding exhibits several advantages over fusion welding in that it produces welds with fewer defects and higher joint efficiency and is capable of joining alloys that are generally considered non-weldable with a fusion weld process. In 1994, NASA-Marshall began collaborating with TWI to transform FSW from a laboratory curiosity to a viable metal joining process suitable for manufacturing hardware. While teamed with TWI, NASA-Marshall began its own FSW research and development effort to investigate possible aerospace applications for the FSW process. The work involved nearly all aspects of FSW development, including process modeling, scale-up issues, applications to advanced materials and development of tooling to use FSW on components of the Space Shuttle with particular emphasis on aluminum tanks. The friction stir welding process involves spinning a pin-tool at an appropriate speed, plunging it into the base metal pieces to be joined, and then translating it along the joint of the work pieces. In aluminum alloys the rotating speed typically ranges from 200 to 400 revolutions per minute and the translation speed is approximately two to five inches per minute. The pin-tool is inserted at a small lead angle from the axis normal to the work piece and requires significant loading along the axis of the tool. An anvil or reaction structure is required behind the welded material to react the load along the axis of the pin tool. The process requires no external heat input, filler material, protective shielding gas or inert atmosphere typical of fusion weld processes. The FSW solid-state weld process has resulted in aluminum welds with significantly higher strengths, higher joint efficiencies and fewer defects than fusion welds used to join similar alloys.

Evaluation of occupational exposure to toxic metals released in the process of aluminum welding.

PubMed

Matczak, Wanda; Gromiec, Jan

2002-04-01

The objective of this study was to evaluate occupational exposure to welding fumes and its elements on aluminum welders in Polish industry. The study included 52 MIG/Al fume samples and 18 TIG/Al samples in 3 plants. Air samples were collected in the breathing zone of welders (total and respirable dust). Dust concentration was determined gravimetrically, and the elements in the collected dust were determined by AAS. Mean time-weighted average (TWA) concentrations of the welding dusts/fumes and their components in the breathing zone obtained for different welding processes were, in mg/m3: MIG/Al fumes mean 6.0 (0.8-17.8), Al 2.1 (0.1-7.7), Mg 0.2 (< 0.1-0.9), Mn 0.014 (0.002-0.049), Cu 0.011 (0.002-0.092), Zn 0.016 (0.002-0.14), Pb 0.009 (0.005-0.025), Cr 0.003 (0.002-0.007), and TIG/Al fumes 0.7 (0.3-1.4), Al 0.17 (0.07-0.50). A correlation has been found between the concentration of the main components and the fume/dust concentrations in MIG/Al and TIG/Al fumes. Mean percentages of the individual components in MIG/Al fumes/dusts were Al: 30 (9-56) percent; Mg: 3 (1-5.6) percent; Mn: 0.2 (0.1-0.3) percent; Cu: 0.2 (< 0.1-1.8) percent; Zn: 0.2 (< 0.1-0.8) percent; Pb: 0.2 (< 0.1-1) percent; Cr: < 0.1 percent. The proportion of the respirable fraction in the fumes and their constituents varied between 10 percent and 100 percent. The results showed that MIG/Al fumes concentration was 1.2 times higher than the American Conference of Governmental Industrial Hygienists (ACGIH) threshold limit value (TLV), and the index of the combined exposure to the determined agents was 2.3 (0.4-8.0), mostly because of high Al2O3 contribution. The background concentrations of the components (ca. 5-10 times lower than those in the breathing zone of the welders) did not exceed the Polish MAC value. The elemental composition of total and respirable fume/dust may differ considerably depending on welding methods, the nature of welding-related operations, and work environment conditions.

Influence of the welding temperature and the welding speed on the mechanical properties of friction stir welds in EN AW-2219-T87

NASA Astrophysics Data System (ADS)

Bachmann, A.; Krutzlinger, M.; Zaeh, M. F.

2018-06-01

Friction Stir Welding (FSW) is an innovative joining technique, which has proven to produce high quality joints in high strength aluminum alloys. Consequently, it is commonly used to manufacture lightweight aerospace structures with stringent requirements. For these structures, it is necessary to ensure a high ultimate tensile strength (UTS). Various studies have reported that the UTS is significantly influenced by the welding parameters. Samples welded with different parameter sets showed a considerably different UTS, despite being free from detectable welding defects (e.g. tunnel defect, voids, or lack of penetration). Based on the observations in the literature, a hypothesis was posed. The welding temperature along with the welding speed determine the UTS of the weld. This study aims to prove this hypothesis experimentally by using temperature-controlled FSW to join plates of EN AW-2219-T87 in butt joint configuration. The welded samples were examined using visual inspection, metallography, X-ray imaging, and uniaxial tensile tests. Finally, a statistical analysis was conducted. Hereby, the hypothesis was confirmed.

Weld leaks rapidly and safely detected

NASA Technical Reports Server (NTRS)

1965-01-01

Test method detects leaks that occur during hydrostatic pressure testing of welded joints in metal tanks. A strip of aluminum foil and a strip of water-soluble paper are placed over the weld. A voltage applied between the tank wall and the foil strip is monitored to detect a decrease in ohmic resistance caused by water leakage into the paper layer.

Small-scale explosive seam welding. [using ribbon explosive encased in lead sheath

NASA Technical Reports Server (NTRS)

Bement, L. J.

1972-01-01

A unique small scale explosive seam welding technique is reported that has successfully joined a variety of aluminum alloys and alloy combinations in thicknesses to 0.125 inch, as well as titanium in thicknesses to 0.056 inch. The explosively welded joints are less than one-half inch in width and apparently have no long length limitation. The ribbon explosive developed in this study contains very small quantities of explosive encased in a flexible thin lead sheath. The evaluation and demonstration of this welding technique was accomplished in three phases: evaluation and optimization of ten major explosive welding variables, the development of four weld joints, and an applicational analysis which included photomicrographs, pressure integrity tests, vacuum effects, and fabrication of some potentially useful structures in aluminum and titanium.

Friction stir scribe welding technique for dissimilar joining of aluminium and galvanised steel

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Tianhao; Sidhar, Harpreet; Mishra, Rajiv S.

Friction stir scribe technology, a derivative of friction stir welding, was applied for the dissimilar lap welding of an aluminum alloy and galvanized mild steel sheets. During the process, the rotating tool with a cobalt steel scribe first penetrated the top material — aluminum — and then the scribe cut the bottom material — steel. The steel was displaced into the upper material to produce a characteristic hook feature. Lap welds were shear tested, and their fracture paths were studied. Welding parameters affected the welding features including hook height, which turned out to be highly related to fracture position. Therefore,more » in this paper, the relationships among welding parameters, hook height, joint strength and fracture position are presented. In addition, influence of zinc coating on joint strength was also studied. Keywords: friction stir scribe technology; dissimilar material welding; zinc coating; hook height; joint strength; fracture position« less

46 CFR 160.035-6 - Construction of aluminum oar-, hand-, and motor-propelled lifeboats.

Code of Federal Regulations, 2010 CFR

2010-10-01

... is to be heat-treated and checked by X-ray to assure a satisfactory weld. When using 5086-H 112 aluminum, the welded area is to be checked by a nondestructive test method such as X-ray, ultrasonic waves...) Dissimilar metals. (1) Where in the construction of aluminum lifeboats the use of dissimilar metals are...

46 CFR 160.035-6 - Construction of aluminum oar-, hand-, and motor-propelled lifeboats.

Code of Federal Regulations, 2011 CFR

2011-10-01

... is to be heat-treated and checked by X-ray to assure a satisfactory weld. When using 5086-H 112 aluminum, the welded area is to be checked by a nondestructive test method such as X-ray, ultrasonic waves...) Dissimilar metals. (1) Where in the construction of aluminum lifeboats the use of dissimilar metals are...

Effect of Heat Treatment on Microstructure and Hot Impact Toughness of Various Zones of P91 Welded Pipes

NASA Astrophysics Data System (ADS)

Pandey, C.; Mahapatra, M. M.

2016-06-01

The new generation super critical thermal power plants are required to operate at enhanced thermal efficiency of over 50% to reduce the fuel consumption and environmental pollution. Creep strength-enhanced ferritic steels, commonly known as Cr-Mo alloys such as P91 (X10CrMoVNb 9-1) are such material of choice for the next generation power plants. The operating requirement of these next generation power plants is that steam temperature of around 650 °C is maintained. For such high-temperature application, creep strength of material is the primary consideration together with adequate weld heat-affected zone (HAZ) toughness. Present work deals with the effect of high service temperature on impact toughness of P91 (X10CrMoVNb 9-1) base material, weld fusion zone, and HAZ. The impact toughness of HAZ for conventional weld groove design and narrow weld groove design has been evaluated experimentally in as-welded and at different post-weld heat treatment conditions. Fractography of the impact toughness specimens of base metal, weld fusion zone, and HAZ was carried out using scanning electron microscope. The effects of heat treatment schemes on the percentage of element present at the fracture surface were also studied.

Friction-Stir Welding and Mathematical Modeling

NASA Technical Reports Server (NTRS)

Rostant, Victor D.

1999-01-01

The friction-stir welding process is a remarkable way for making butt and lap joints in aluminum alloys. This process operates by passing a rotating tool between two closely butted plates. Through this process it generates a lot of heat and heated material is stirred from both sides of the plates in which the outcome will one high quality weld. My research has been done to study the FSW through mathematical modeling, and using modeling to better understand what take place during the friction-stir weld.

Ultrasonic Welding of Hybrid Joints

NASA Astrophysics Data System (ADS)

Wagner, Guntram; Balle, Frank; Eifler, Dietmar

2012-03-01

A central research field of the Institute of Materials Science and Engineering at the University of Kaiserslautern (WKK), Germany, is the realization of innovative hybrid joints by ultrasonic metal welding. This article gives an overview of suitable ultrasonic welding systems as well as of essential machine and material parameters, which influence the quality of the welds. Besides the ultrasonic welding of dissimilar metals such as Al to Cu or Al to steels, the welds between newly developed materials like aluminum foam sandwiches or flat flexible cables also can be realized. Moreover, the joining of glass and ceramic to sheet metals is a point of interest at the WKK. By using the ultrasonic metal welding process, it is possible to realize metal/glass welds with tensile shear strengths of 50 MPa. For metal/ceramic joints, the shear strengths values up to 150 MPa were measured. Finally, selected results about the occurring bonding mechanisms will be discussed.

Theoretical Model of the Effect of Crack Tip Blunting on the Ultimate Tensile Strength of Welds in 2219-T87 Aluminum

NASA Technical Reports Server (NTRS)

Beil, R. J.

1982-01-01

A theoretical model representing blunting of a crack tip radius through diffusion of vacancies is presented. The model serves as the basis for a computer program which calculates changes, due to successive weld heat passes, in the ultimate tensile strength of 2219-T81 aluminum. In order for the model to yield changes of the same order in the ultimate tensile strength as that observed experimentally, a crack tip radius of the order of .001 microns is required. Such sharp cracks could arise in the fusion zone of a weld from shrinkage cavities or decohered phase boundaries between dendrites and the eutectic phase, or, possibly, from plastic deformation due to thermal stresses encountered during the welding process. Microstructural observations up to X2000 (resolution of about .1 micron) did not, in the fusion zone, show structural details which changed significantly under the influence of a heat pass, with the exception of possible small changes in the configuration of the interdendritic eutectic and in porosity build-up in the remelt zone.

Indentation Creep Behavior of Nugget Zone of Friction Stir Welded 2014 Aluminum Alloy

NASA Astrophysics Data System (ADS)

Das, Jayashree; Robi, P. S.; Sankar, M. Ravi

2018-04-01

The present study is aimed at evaluating the creep behavior of the nugget zone of friction welded 2014 Aluminum alloy by indentation creep tests. Impression creep testing was carried out at different temperatures of 300°C, 350°C and 400 °C with stress 124.77MPa, 187.16MPa, 249.55 MPa using a 1.0 mm diameter WC indenter. Experiments were conducted till the curve enters the steady state creep region. Constitutive modeling of creep behavior was carried out considering the temperature, stress and steady state creep rate. Microstructural investigation of the crept specimen at 400°C temperature and 187.16 MPa load was carried out and found that the small precipitates accumulate along the grain boundaries at the favorable conditions of the creep temperature and stress, new precipitates evolve due to the ageing. The grains are broken and deformed due to the creep phenomena.

Laser Ablation Cleaning of Self-Reacting Friction Stir Weld Seam Surfaces: A Preliminary Evaluation

NASA Technical Reports Server (NTRS)

Nunes, A. C., Jr.; Russell, C. K.; Brooke, S. A.; Parry, Q.; Lowrey, N. M.

2014-01-01

Anodized aluminum panels were cleaned by three lasers at three separate sites with a view to determining whether more economical laser cleaning might supplant current manual cleaning methods for preparation of surfaces to be welded by the self-reacting friction stir process. Uncleaned panels yielded welds exhibiting residual oxide defect (ROD) and failing at very low stresses along the trace of the weld seam. Manually cleaned panels yielded welds without ROD; these welds failed at nominal stress levels along an angled fracture surface not following the weld seam trace. Laser cleaned panels yielded welds failing at intermediate stress levels. The inadequacy of the laser cleaning processes leaves questions: Was the anodized aluminum test too stringent to represent actual cleaning requirements? Were the wrong laser cleaning techniques/parameters used for the study? Is the laser cleaning mechanism inadequate for effective preweld surface cleaning?

Physical and chemical characterization of airborne particles from welding operations in automotive plants.

PubMed

Dasch, Jean; D'Arcy, James

2008-07-01

Airborne particles were characterized from six welding operations in three automotive plants, including resistance spot welding, metal inert gas (MIG) welding and tungsten inert gas (TIG) welding of aluminum and resistance spot welding, MIG welding and weld-through sealer of galvanized steel. Particle levels were measured throughout the process area to select a sampling location, followed by intensive particle sampling over one working shift. Temporal trends were measured, and particles were collected on filters to characterize their size and chemistry. In all cases, the particles fell into a bimodal size distribution with very large particles >20 mum in diameter, possibly emitted as spatter or metal expulsions, and very small particles about 1 mum in diameter, possibly formed from condensation of vaporized metal. The mass median aerodynamic diameter was about 1 mum, with only about 7% of the particle mass present as ultrafine particles <100 nm. About half the mass of aluminum welding particles could be accounted for by chemical analysis, with the remainder possibly present as oxygen. Predominant species were organic carbon, elemental carbon, iron, and aluminum. More than 80% of the particle mass could be accounted for from steel welding, primarily present as iron, organic carbon, zinc, and copper. Particle concentrations and elemental concentrations were compared with allowable concentrations as recommended by the Occupational Safety and Health Administration and the American Conference of Governmental Industrial Hygienists. In all cases, workplace levels were at least 11 times lower than recommended levels.

Welding of Aluminum Alloys to Steels: An Overview

DTIC Science & Technology

2013-08-01

and deformations are a few examples of the unwanted consequences which somehow would lead to brittle fracture, fatigue fracture, shape instability...was made under the copper tips of the spot welding machine. The fatigue results showed higher fatigue strength of the joints with transition layer...kHz ultrasonic butt welding system with a vibration source applying eight bolt-clamped Langevin type PZT transducers and a 50 kW static induction

Grain refinement control in gas-shielded arc welding of aluminum tubing

NASA Technical Reports Server (NTRS)

Iceland, W. F.; Whiffen, E. L.

1974-01-01

When sections are being welded, operator varies pulse rate of power supply and simultaneously monitors signal on oscilloscope until rate is found which produces maximum arc gas voltage. Remainder of welding is performed with power supply set at this pulse rate, producing desired maximum weld puddle agitation and fine uniform weld of grain structure.

Femtosecond fiber laser welding of dissimilar metals.

PubMed

Huang, Huan; Yang, Lih-Mei; Bai, Shuang; Liu, Jian

2014-10-01

In this paper, welding of dissimilar metals was demonstrated for the first time, to the best of our knowledge, by using a high-energy high-repetition-rate femtosecond fiber laser. Metallurgical and mechanical properties were investigated and analyzed under various processing parameters (pulse energy, repetition rate, and welding speed). Results showed that the formation of intermetallic brittle phases and welding defects could be effectively reduced. Strong welding quality with more than 210 MPa tensile strength for stainless steel-aluminum and 175 MPa tensile strength for stainless steel-magnesium has been demonstrated. A minimal heat affected zone and uniform and homogenous phase transformation in the welding region have been demonstrated. This laser-welding technique can be extended for various applications in semiconductor, automobile, aerospace, and biomedical industries.

Experimental Studies on Grooved Double Pipe Heat Exchanger with Different Groove Space

NASA Astrophysics Data System (ADS)

Sunu, P. W.; Arsawan, I. M.; Anakottapary, D. S.; Santosa, I. D. M. C.; Yasa, I. K. A.

2018-01-01

Experimental studies were performed on grooved double pipe heat exchanger (DPHE) with different groove space. The objective of this work is to determine optimal heat transfer parameter especially logarithmic mean temperature difference (LMTD). The document in this paper also provides the total heat observed by the cold fluid. The rectangular grooves were incised on outer surface of tube side with circumferential pattern and two different grooves space, namely 1 mm and 2 mm. The distance between grooves and the grooves high were kept constant, 8 mm and 0.3 mm respectively. The tube diameter is 20 mm and its made of aluminium. The shell is made of acrylic which has 28 mm in diameter. Water is used as the working fluid. Using counter flow scheme, the cold fluid flows in the annulus room of DPHE. The volume flowrate of hot fluid remains constant at 15 lpm. The volume flowrate of cold fluid were varied from 11 lpm to 15 lpm. Based on logarithmic mean temperature difference analysis, the LMTD of 1 mm grooves space was higher compared to that of 2 mm grooves space. The smaller grooves space has more advantage since the recirculating region are increased which essentially cause larger heat transfer enhancement.

Metallography of Battery Resistance Spot Welds

NASA Technical Reports Server (NTRS)

Martinez, J. E.; Johannes, L. B.; Gonzalez, D.; Yayathi, S.; Figuered, J. M.; Darcy, E. C.; Bilc, Z. M.

2015-01-01

Li-ion cells provide an energy dense solution for systems that require rechargeable electrical power. However, these cells can undergo thermal runaway, the point at which the cell becomes thermally unstable and results in hot gas, flame, electrolyte leakage, and in some cases explosion. The heat and fire associated with this type of event is generally violent and can subsequently cause damage to the surrounding system or present a dangerous risk to the personnel nearby. The space flight environment is especially sensitive to risks particularly when it involves potential for fire within the habitable volume of the International Space Station (ISS). In larger battery packs such as Robonaut 2 (R2), numerous Li-ion cells are placed in parallel-series configurations to obtain the required stack voltage and desired run-time or to meet specific power requirements. This raises a second and less obvious concern for batteries that undergo certification for space flight use: the joining quality at the resistance spot weld of battery cells to component wires/leads and battery tabs, bus bars or other electronic components and assemblies. Resistance spot welds undergo materials evaluation, visual inspection, conductivity (resistivity) testing, destructive peel testing, and metallurgical examination in accordance with applicable NASA Process Specifications. Welded components are cross-sectioned to ensure they are free of cracks or voids open to any exterior surface. Pore and voids contained within the weld zone but not open to an exterior surface, and are not determined to have sharp notch like characteristics, shall be acceptable. Depending on requirements, some battery cells are constructed of aluminum canisters while others are constructed of steel. Process specific weld schedules must be developed and certified for each possible joining combination. The aluminum canisters' positive terminals were particularly difficult to weld due to a bi-metal strip that comes ultrasonically

Zn2+ selectively stabilizes FdU-substituted DNA through a unique major groove binding motif

PubMed Central

Ghosh, Supratim; Salsbury, Freddie R.; Horita, David A.; Gmeiner, William H.

2011-01-01

We report, based on semi-empirical calculations, that Zn2+ binds duplex DNA containing consecutive FdU–dA base pairs in the major groove with distorted trigonal bipyramidal geometry. In this previously uncharacterized binding motif, O4 and F5 on consecutive FdU are axial ligands while three water molecules complete the coordination sphere. NMR spectroscopy confirmed Zn2+ complexation occurred with maintenance of base pairing while a slight hypsochromic shift in circular dichroism (CD) spectra indicated moderate structural distortion relative to B-form DNA. Zn2+ complexation inhibited ethidium bromide (EtBr) intercalation and stabilized FdU-substituted duplex DNA (ΔTm > 15°C). Mg2+ neither inhibited EtBr complexation nor had as strong of a stabilizing effect. DNA sequences that did not contain consecutive FdU were not stabilized by Zn2+. A lipofectamine preparation of the Zn2+–DNA complex displayed enhanced cytotoxicity toward prostate cancer cells relative to the individual components prepared as lipofectamine complexes indicating the potential utility of Zn2+–DNA complexes for cancer treatment. PMID:21296761

Weld-brazing - a new joining process. [combination resistance spot welding and brazing of titanium alloys

NASA Technical Reports Server (NTRS)

Bales, T. T.; Royster, D. M.; Arnold, W. E., Jr.

1972-01-01

A joining process designated weld brazing which combines resistance spot welding and brazing has been developed. Resistance spot welding is used to position and align the parts as well as to establish a suitable faying surface gap for brazing. Fabrication is then completed by capillary flow of the braze alloy into the joint. The process has been used successfully to fabricate Ti-6Al-4V titanium alloy joints using 3003 aluminum braze alloy. Test results obtained on single overlap and hat-stiffened structural specimens show that weld brazed joints are superior in tensile shear, stress rupture, fatigue, and buckling than joint fabricated by spotwelding or brazing. Another attractive feature of the process is that the brazed joints is hermetically sealed by the braze material.

Effects of porosity on weld-joint tensile strength of aluminum alloys

NASA Technical Reports Server (NTRS)

Lovoy, C. V.

1974-01-01

Tensile properties in defect-free weldments of aluminum alloys 2014-T6 and 2219-T87 (sheet and plate) are shown to be related to the level or concentration of induced simulated porosity. The scatter diagram shows that the ultimate tensile strength of the weldments displays the most pronounced linear relationship with the level of porosity. The relationships between yield strength or elongation and porosity are either trivial or inconsequential in the lower and intermediate levels of porosity content. In highly concentrated levels of porosity, both yield strength and elongation values decrease markedly. Correlation coefficients were obtained by simple straight line regression analysis between the variables of ultimate tensile strength and pore level. The coefficients were greater, indicating a better correlation, using a pore area accumulation concept or pore volume accumulation than the accumulation of the pore diameters. These relationships provide a useful tool for assessing the existing aerospace radiographic acceptance standards with respect to permissible porosity. In addition, these relationships, in combination with known design load requirements, will serve as an engineering guideline in determining when a weld repair is necessary based on accumulative pore level as detected by radiographic techniques.

Effects of surface preparation on quality of aluminum alloy weldments

NASA Technical Reports Server (NTRS)

Kizer, D.; Saperstein, Z.

1968-01-01

Study of surface preparations and surface contamination effects on the welding of 2014 aluminum involves several methods of surface analysis to identify surface properties conducive to weld defects. These methods are radioactive evaporation, spectral reflectance mass spectroscopy, gas chromatography and spark emission spectroscopy.