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Sample records for investment casting process

  1. Prediction of ALLOY SHRINKAGE FACTORS FOR THE INVESTMENT CASTING PROCESS

    SciTech Connect

    Sabau, Adrian S

    2006-01-01

    This study deals with the experimental measurements and numerical predictions of alloy shrinkage factors (SFs) related to the investment casting process. The dimensions of the A356 aluminum alloy casting were determined from the numerical simulation results of solidification, heat transfer, fluid dynamics, and deformation phenomena. The investment casting process was carried out using wax patterns of unfilled wax and shell molds that were made of fused silica with a zircon prime coat. The dimensions of the die tooling, wax pattern, and casting were measured, in order to determine the actual tooling allowances. Several numerical simulations were carried out, to assess the level of accuracy for the casting shrinkage. The solid fraction threshold, at which the transition from the fluid dynamics to the solid dynamics occurs, was found to be important in predicting shrinkage factors (SFs). It was found that accurate predictions were obtained for all measued dimensions when the shell mold was considered a deformable material.

  2. Recent advances in the application of modeling to the investment casting process

    SciTech Connect

    Foran, R.K.; Hansen, T.; Mueller, B.

    1995-12-31

    Process modeling is being used to reduce development cycle time and cost, and improve the quality of investment castings. A critical component of modeling development is to improve model accuracy. Accuracy improvements are necessary not only for basic solutions such as fluid flow and thermal gradients, but they are also a prerequisite for more sophisticated analysis such as thermal stress and nonfill. This paper discusses accuracy improvements resulting from more complete and accurate thermophysical databases, improved estimates of the contact conductance between different materials, and more metallurgically correct methods to track latent heat evolution. Nonfill prediction techniques have been developed for the case of metal freeze off and applied to titanium castings. These results are being used to develop economical, high quality products and investment casting processes.

  3. Mineral processing techniques for recycling investment casting shell

    SciTech Connect

    Dahlin, Cheryl L.; Nilsen, David N.; Dahlin, David C.; Hunt, Alton H.; Collins, W. Keith

    2002-01-01

    The Albany Research Center of the U.S. Department of Energy used materials characterization and minerals beneficiation methods to separate and beneficially modify spent investment-mold components to identify recycling opportunities and minimize environmentally sensitive wastes. The physical and chemical characteristics of the shell materials were determined and used to guide bench-scale research to separate reusable components by mineral-beneficiation techniques. Successfully concentrated shell materials were evaluated for possible use in new markets.

  4. Friction Stir Processing of Investment-Cast Ti-6Al-4V: Microstructure and Properties

    NASA Astrophysics Data System (ADS)

    Pilchak, A. L.; Norfleet, D. M.; Juhas, M. C.; Williams, J. C.

    2008-07-01

    Investment-cast titanium components are becoming increasingly common in the aerospace industry due to the ability to produce large, complex, one-piece components that were previously fabricated by mechanically fastening multiple pieces together. The fabricated components are labor-intensive and the fastener holes are stress concentrators and prime sites for fatigue crack initiation. The castings are typically hot-isostatically-pressed (HIP) to close internal porosity, but have a coarse, fully lamellar structure that has low resistance to fatigue crack initiation. The as-cast + HIP material exhibited 1- to 1.5-mm prior β grains containing a fully lamellar α + β microstructure consistent with slow cooling from above the β transus. Friction stir processing (FSP) was used to locally modify the microstructure on the surface of an investment-cast Ti-6Al-4V plate. Friction stir processing converted the as-cast microstructure to fine (1- to 2-μm) equiaxed α grains. Using micropillars created with a dual-beam focused ion beam device, it was found that the fine-grained equiaxed structure has about a 12 pct higher compressive yield stress. In wrought products, higher strength conditions are more resistant to fatigue crack initiation, while the coarse lamellar microstructure in the base material has better fatigue crack growth resistance. In combination, these two microstructures can increase the fatigue life of titanium alloy castings by increasing the number of cycles prior to crack initiation while retaining the same low-crack growth rates of the colony microstructure in the remainder of the component. In the current study, high-cycle fatigue testing of investment-cast Ti-6Al-4V was performed on four-point bend specimens. Early results show that FSP can increase fatigue strength dramatically.

  5. Investment casting design of experiment. Final report

    SciTech Connect

    Owens, R.

    1997-10-01

    Specific steps in the investment casting process were analyzed in a designed experiment. The casting`s sensitivity to changes in these process steps was experimentally determined Dimensional and radiographic inspection were used to judge the sensitivity of the casting. Thirty-six castings of different pedigrees were poured and measured. Some of the dimensional inspection was conducted during the processing. It was confirmed that wax fixturing, number of gates, gate location, pour and mold temperature, pour speed, and cooling profile all affected the radiographic quality of the casting. Gate and runner assembly techniques, number of gates, and mold temperature affect the dimensional quality of the casting.

  6. Effects of process variables on the properties of YBa2Cu3O(7-x) ceramics formed by investment casting

    NASA Technical Reports Server (NTRS)

    Hooker, M. W.; Taylor, T. D.; Leigh, H. D.; Wise, S. A.; Buckley, J. D.; Vasquez, P.; Buck, G. M.; Hicks, L. P.

    1993-01-01

    An investment casting process has been developed to produce net-shape, superconducting ceramics. In this work, a factorial experiment was performed to determine the critical process parameters for producing cast YBa2Cu3O7 ceramics with optimum properties. An analysis of variance procedure indicated that the key variables in casting superconductive ceramics are the particle size distribution and sintering temperature. Additionally, the interactions between the sintering temperature and the other process parameters (e.g., particle size distribution and the use of silver dopants) were also found to influence the density, porosity, and critical current density of the fired ceramics.

  7. Microstructural Changes Due to Friction Stir Processing of Investment-Cast Ti-6Al-4V

    NASA Astrophysics Data System (ADS)

    Pilchak, A. L.; Juhas, M. C.; Williams, J. C.

    2007-02-01

    Friction stir processing (FSP) was used to modify the coarse fully lamellar microstructure on the surface of investment-cast and hot isostatically pressed (HIP) Ti-6Al-4V plate. The α colony and platelet structure in the base material (BM) was refined such that the effective slip length was reduced from the α colony size of the BM, several hundred microns, to that of fine equiaxed primary α grains that are on the order of 1 μm. This change in the microstructure resulting from FSP is expected to increase fatigue crack initiation resistance making it beneficial for titanium components for aerospace applications. The as-cast coarse lamellar microstructure has superior fatigue crack growth resistance compared to other microstructures that can be obtained by thermomechanical processing. Thus, it is likely that an increase in fatigue life is obtainable by FSP. Given the growing interest in friction stir welding (FSW) and FSP of titanium alloys, we believe some consistent microstructural descriptors will help avoid confusion. Accordingly, we propose terminology to standardize the descriptions of the microstructures created during FSP and FSW of titanium alloys. We also describe the microstructure changes that occur in the stir zone (SZ), transition zone (TZ), and heat-affected zone (HAZ) during FSP of Ti-6Al-4V.

  8. Combination Of Investment And Centrifugal Casting

    NASA Technical Reports Server (NTRS)

    Creeger, Gordon A.

    1994-01-01

    Modifications, including incorporation of centrifugal casting, made in investment-casting process reducing scrap rate. Used to make first- and second-stage high-pressure-fuel-turbopump nozzles, containing vanes with thin trailing edges and other thin sections. Investment mold spun for short time while being filled, and stopped before solidification occurs. Centrifugal force drives molten metal into thin trailing edges, ensuring they are filled. With improved filling, preheat and pour temperatures reduced and solidification hastened so less hot tearing.

  9. Effect of Friction Stir Processing on Fatigue Behavior of an Investment Cast Al-7Si-0.6 Mg Alloy

    SciTech Connect

    Jana, Saumyadeep; Mishra, Rajiv S.; Baumann, John B.; Grant, Glenn J.

    2010-02-01

    Cast aluminum alloys in general show poor fatigue performance due to presence of defects. Friction stir processing (FSP) can be used as a tool for enhancing mechanical properties of cast alloys by eliminating such defects. In the present study FSP led to a five times improvement in fatigue life of an investment cast Al-7Si-0.6Mg hypoeutectic alloy. The reason for such enhancement was linked to closure of casting porosity which acted as crack nucleation sites in the as-cast condition. Porosity acted as notches in the as-cast alloy and led to an order of magnitude higher crack growth rate. As FSP eliminated the porosity and refined Si particles, crack growth rate dropped due to the elimination of the notch effect together with increased crack path tortuosity. Finally, short crack behavior was noted in both cast and FSP specimens. The critical crack length where transition from short crack to long crack behavior took place is related to respective microstructural characteristic dimensions.

  10. Advanced Pattern Material for Investment Casting Applications

    SciTech Connect

    F. Douglas Neece Neil Chaudhry

    2006-02-08

    Cleveland Tool and Machine (CTM) of Cleveland, Ohio in conjunction with Harrington Product Development Center (HPDC) of Cincinnati, Ohio have developed an advanced, dimensionally accurate, temperature-stable, energy-efficient and cost-effective material and process to manufacture patterns for the investment casting industry. In the proposed technology, FOPAT (aFOam PATtern material) has been developed which is especially compatible with the investment casting process and offers the following advantages: increased dimensional accuracy; increased temperature stability; lower cost per pattern; less energy consumption per pattern; decreased cost of pattern making equipment; decreased tooling cost; increased casting yield. The present method for investment casting is "the lost wax" process, which is exactly that, the use of wax as a pattern material, which is then melted out or "lost" from the ceramic shell. The molten metal is then poured into the ceramic shell to produce a metal casting. This process goes back thousands of years and while there have been improvements in the wax and processing technology, the material is basically the same, wax. The proposed technology is based upon an established industrial process of "Reaction Injection Molding" (RIM) where two components react when mixed and then "molded" to form a part. The proposed technology has been modified and improved with the needs of investment casting in mind. A proprietary mix of components has been formulated which react and expand to form a foam-like product. The result is an investment casting pattern with smooth surface finish and excellent dimensional predictability along with the other key benefits listed above.

  11. Neutron radiography inspection of investment castings.

    PubMed

    Richards, W J; Barrett, J R; Springgate, M E; Shields, K C

    2004-10-01

    Investment casting, also known as the lost wax process, is a manufacturing method employed to produce near net shape metal articles. Traditionally, investment casting has been used to produce structural titanium castings for aero-engine applications with wall thickness less than 1 in (2.54 cm). Recently, airframe manufacturers have been exploring the use of titanium investment casting to replace components traditionally produced from forgings. Use of titanium investment castings for these applications reduces weight, cost, lead time, and part count. Recently, the investment casting process has been selected to produce fracture critical structural titanium airframe components. These airframe components have pushed the traditional inspection techniques to their physical limits due to cross sections on the order of 3 in (7.6 cm). To overcome these inspection limitations, a process incorporating neutron radiography (n-ray) has been developed. In this process, the facecoat of the investment casting mold material contains a cocalcined mixture of yttrium oxide and gadolinium oxide. The presence of the gadolinium oxide, allows for neutron radiographic imaging (and eventual removal and repair) of mold facecoat inclusions that remain within these thick cross sectional castings. Probability of detection (POD) studies have shown a 3 x improvement of detecting a 0.050 x 0.007 in2 (1.270 x 0.178 mm2) inclusion of this cocalcined material using n-ray techniques when compared to the POD using traditional X-ray techniques. Further, it has been shown that this n-ray compatible mold facecoat material produces titanium castings of equal metallurgical quality when compared to the traditional materials. Since investment castings can be very large and heavy, the neutron radiography facilities at the University of California, Davis McClellan Nuclear Radiation Center (UCD/MNRC) were used to develop the inspection techniques. The UCD/MNRC has very unique facilities that can handle large

  12. Gelcasting Alumina Cores for Investment Casting

    SciTech Connect

    Janney, M A; Klug, F J

    2001-01-01

    General Electric currently uses silica investment casting cores for making superalloy turbine blades. The silica core technology does not provide the degree of dimensional control needed for advanced turbine system manufacture. The sum of the various process variables in silica core manufacturing produces cores that have more variability than is allowed for in advanced, power-generation gas turbine airfoils.

  13. WinMod: An expert advisor for investment casting

    SciTech Connect

    Bivens, H.P.; Williamson, G.A. Jr.; Luger, G.F.; Erdmann, R.G.; Maguire, M.C.; Baldwin, M.D.; Anderson, D.J.

    1998-04-01

    Investment casting is an important method for fabricating a variety of high quality components in mechanical systems. Cast components, unfortunately, have a large design and gate/runner build time associated with their fabrication. In addition, casting engineers often require many years of actual experience in order to consistently pour high quality castings. Since 1989, Sandia National Laboratories has been investigating casting technology and software that will reduce the time overhead involved in producing quality casts. Several companies in the casting industry have teamed up with Sandia to form the FASTCAST Consortium. One result of this research and the formation of the FASTCAST consortium is the creation of the WinMod software, an expert casting advisor that supports the decision making process of the casting engineer through visualization and advice to help eliminate possible casting defects.

  14. Some Investigations on Hardness of Investment Casting Process After Advancements in Shell Moulding for Reduction in Cycle Time

    NASA Astrophysics Data System (ADS)

    Singh, R.; Mahajan, V.

    2014-07-01

    In the present work surface hardness investigations have been made on acrylonitrile butadiene styrene (ABS) pattern based investment castings after advancements in shell moulding for replication of biomedical implants. For the present study, a hip joint, made of ABS material, was fabricated as a master pattern by fused deposition modelling (FDM). After preparation of master pattern, mold was prepared by deposition of primary (1°), secondary (2°) and tertiary (3°) coatings with the addition of nylon fibre (1-2 cm in length of 1.5D). This study outlines the surface hardness mechanism for cast component prepared from ABS master pattern after advancement in shell moulding. The results of study highlight that during shell production, fibre modified shells have a much reduced drain time. Further the results are supported by cooling rate and micro structure analysis of casting.

  15. Shrinkage Prediction for the Investment Casting of Stainless Steels

    SciTech Connect

    Sabau, Adrian S

    2007-01-01

    In this study, the alloy shrinkage factors were obtained for the investment casting of 17-4PH stainless steel parts. For the investment casting process, unfilled wax and fused silica with a zircon prime coat were used for patterns and shell molds, respectively. Dimensions of the die tooling, wax pattern, and casting were measured using a Coordinate Measurement Machine in order to obtain the actual tooling allowances. The alloy dimensions were obtained from numerical simulation results of solidification, heat transfer, and deformation phenomena. The numerical simulation results for the shrinkage factors were compared with experimental results.

  16. Investment cast AISI H13 tooling for automotive applications

    SciTech Connect

    Maguire, M.C.; Baldwin, M.D.; Hochanadel, P.W.; Edwards, G.R.

    1995-07-01

    While many techniques exist for production of soft tooling, for die casting there is limited recent experience with cast tooling. The most common US alloy used for manufacture of die casting tooling is wrought AISI H13. If the performance of the cast material is comparable to the wrought counterpart, the use of investment cast HI 3 tooling directly from patterns made via rapid prototyping is of considerable interest. A metallurgical study of investment cast H13 was conducted to evaluate the mechanical behavior in simulated die casting applications. Variable thickness plate investment castings of AISI H13 hot work die steel were produced and characterized in the as-cast and heat-treated conditions. The characterization included light microscopy and mechanical testing. Wrought samples of standard and premium grade H13 were heat-treated and characterized similarly for comparison. Microstructural differences were observed in as-cast samples produced in different section thicknesses. Dendrite cell size and carbide morphology constituted the most prominent microstructural differences observed. After a full heat-treatment, microstructural differences between the wrought material and cast materials were slight regardless of section thickness.The mechanical properties of the cast and heat-treated material proved similar to the properties of the standard heat-treated wrought material. A thermal fatigue testing unit was to con-elate the heat checking susceptibility of H13 steel to its processing and consequent microstructural condition. Surface hardness decreased significantly with thermal cycling, and heat checking was observed in as few as 50 cycles. Thermal softening and thermal fatigue susceptibility were quantified and discussed relative to the microstructural conditions created by processing and heat-treatment. It was found that the premium grade wrought H13 steel provided the best overall resistance to heat checking.

  17. Probabilistic modeling of solidification grain structure in investment castings

    SciTech Connect

    Upadhya, G.K.; Yu, K.O.; Layton, M.A.; Paul, A.J.

    1995-12-31

    A probabilistic approach for modeling the evolution of grain structure in investment castings has been developed. The approach differs from the classical Monte Carlo simulations of microstructural evolution in that it uses the results from a heat transfer simulation of the investment casting process for determining the probabilities of nucleation and growth. The model was used to predict the solidification grain structure in castings. The model is quasi-3D, since it uses the information from a 3D simulation of heat transfer to predict the grain structure developed in any 2D-section of the casting. Structural transitions such as columnar/equiaxed transition can also be predicted, using suitable transition criteria. Results from the model have been validated by comparison with actual micrographs from experimental investment castings. In the first case, simulations were performed for a simple plate shaped casting of superalloy Rene 77. The effects of mold insulation as well as metal pour and mold preheat temperatures on the grain size of the casting were studied. In the second example, the casting of a complex-shaped jet engine component made of superalloy IN718 was simulated. Simulation results were seen to match very well with experiments.

  18. The Effect of Friction Stir Processing on the Mechanical Properties of Investment Cast and Hot Isostatically Pressed Ti-6Al-4V

    NASA Astrophysics Data System (ADS)

    Pilchak, A. L.; Williams, J. C.

    2011-06-01

    Friction-stir (FS) processing was used to modify the coarse, fully lamellar microstructure of investment cast and hot isostatically pressed (HIP'ed) Ti-6Al-4V. The effect of FS processing on mechanical properties was investigated using microtensile and four-point bend fatigue testing. The tensile results showed a typical microstructure dependence where yield strength and ultimate tensile strength both increased with decreasing slip length. Depending on the processing parameters, fatigue strength at 107 cycles was increased by 20 pct or 60 pct over that of the investment cast and HIP'ed base material. These improvements have been verified with a statistically significant number of tests. The results have been discussed in terms of the resistance of each microstructure fatigue crack initiation and small crack propagation. For comparison, a limited number of fatigue tests was performed on α + β forged Ti-6Al-4V with varying primary α volume fraction and also on investment cast material heat treated to produce a bi-lamellar condition.

  19. Rapid Tooling via Investment Casting and Rapid Prototype Patterns

    SciTech Connect

    Baldwin, Michael D.

    1999-06-01

    The objective of this work to develop the materials processing and design technologies required to reduce the die development time for metal mold processes from 12 months to 3 months, using die casting of Al and Mg as the example process. Sandia demonstrated that investment casting, using rapid prototype patterns produced from Stereo lithography or Selective laser Sintering, was a viable alternative/supplement to the current technology of machining form wrought stock. A demonstration die insert (ejector halt) was investment cast and subsequently tested in the die casting environment. The stationary half of the die insert was machined from wrought material to benchmark the cast half. The two inserts were run in a die casting machine for 3,100 shots of aluminum and at the end of the run no visible difference could be detected between the cast and machined inserts. Inspection concluded that the cast insert performed identically to the machined insert. Both inserts had no indications of heat checking or degradation.

  20. Predicting Pattern Tooling and Casting Dimensions for Investment Casting - Phase II

    SciTech Connect

    Sabau, Adrian S

    2005-09-01

    The investment casting process allows the production of complex-shape parts and close dimensional tolerances. One of the most important phases in the investment casting process is the design of the pattern die. Pattern dies are used to create wax patterns by injecting wax into dies. The wax patterns are used to create a ceramic shell by the application of a series of ceramic coatings, and the alloy is cast into the dewaxed shell mold (Fig. 1.1). However, the complexity of shape and the close dimensional tolerances required in the final casting make it difficult to determine tooling dimensions. The final linear dimension of the casting depends on the cumulative effects of the linear expansions or contractions in each step of the investment casting process (Fig. 1.2). In most cases, the mold geometry or cores restrict the shrinkage of the pattern or the cast part, and the final casting dimensions may be affected by time-dependent processes such as viscoelastic deformation of the wax, and viscoplastic creep and plastic deformations of the shell and alloy. The pattern die is often reworked several times to produce castings whose dimensions are within acceptable tolerances. To date, investment casting technology has been based on hands-on training and experience. Technical literature is limited to experimental, phenomenological studies aimed at obtaining empirical correlations for quick and easy application in industry. The goal of this project was to predict casting dimensions for investment castings in order to meet blueprint nominal during the first casting run. Several interactions have to be considered in a coupled manner to determine the shrinkage factors: these are the die-wax, wax-shell, and shell-alloy interactions (as illustrated in Fig. 1.3). In this work, the deformations of the die-wax and shell-alloy systems were considered in a coupled manner, while the coupled deformation of the wax-shell system was not considered. Future work is needed in order to

  1. Rapid prototyping: A paradigm shift in investment casting

    SciTech Connect

    Atwood, C.L.; Maguire, M.C.; Baldwin, M.D.; Pardo, B.T.

    1996-09-01

    The quest for fabricating complex metal parts rapidly and with minimal cost has brought rapid prototyping (RP) processes to the forefront of the investment casting industry. Relatively recent advances in DTM Corporation`s selective laser sintering (SLS) and 3D Systems stereolithography (SL) processes have had a significant impact on the overall quality of patterns produced using these rapid prototyping processes. Sandia National Laboratories uses patterns generated from rapid prototyping processes to reduce the cycle time and cost of fabricating prototype and small lot production parts in support of a program called FASTCAST. The SLS process is used to fabricate patterns from materials such as investment casting wax, polycarbonate, and a new material called TrueForm PM{trademark}. With the timely introduction of each of these materials, the quality of patterns fabricated has improved. The development and implementation of SL QuickCast{trademark} software has enabled this process to produce highly accurate patterns for use in investment casting. This paper focuses on the successes with these new pattern materials and the infrastructure required to cast rapid prototyping patterns successfully. In addition, a brief overview of other applications of rapid prototyping at Sandia will be discussed.

  2. Effect of Friction Stir Processing on Microstructure and Tensile Properties of an Investment Cast Al-7Si-0.6Mg Alloy

    SciTech Connect

    Jana, Saumyadeep; Mishra, Rajiv S.; Baumann, John B.; Grant, Glenn J.

    2010-10-01

    Friction stir processing (FSP) is emerging as a promising tool for microstructural modification. The present study assesses the effects of FSP on the microstructure and mechanical properties of an investment cast Al-7Si-Mg alloy. FSP eliminates porosity and significantly refines eutectic Si particles. The extent of particle refinement varied with changes in processing conditions. High tool rotation rate and low to intermediate tool traverse speed generated a higher volume fraction of finer particles. Tensile ductility changed significantly as a result of FSP, whereas UTS improved only marginally. Yield strength was similar in both cast and FSPed samples under various heat treated conditions, with the highest value obtained after a T6 heat treatment. Further, FSP caused significant grain refinement in the stir zone, subsequently transforming into very coarse grains as abnormal grain growth (AGG) occurred during solution treatment at high temperature.

  3. Efficient Runner Networks for Investment Castings

    SciTech Connect

    GIVLER,RICHARD C.; SAYLORS,DAVID B.

    2000-07-18

    We present a computational method that finds an efficient runner network for an investment casting, once the gate locations have been established. The method seeks to minimize a cost function that is based on total network volume. The runner segments are restricted to lie in the space not occupied by the part itself. The collection of algorithms has been coded in C and runner designs have been computed for several real parts, demonstrating substantial reductions in rigging volume.

  4. Modeling and control of casting and welding processes

    SciTech Connect

    Kou, S.; Mehrabian, R.

    1986-01-01

    This book contains papers divided among the following sections: process monitor and control in welding; plasma processing and refining; strip casting; modelling of welding processes; CAD/CAM in casting; investment and die casting; ingot, continuous and other shape casting; and rapid solidification and microstructural evolution.

  5. Face Coat Materials Through Sessile Drop and Investment Casting Methods

    NASA Astrophysics Data System (ADS)

    Cheng, Xu; Yuan, Chen; Blackburn, Stuart; Withey, Paul A.

    2014-06-01

    Investment casting is uniquely suited to the manufacture of Ti alloys for the production of near net-shape components, reducing material waste, and machining costs. Because of the high reactivity of titanium and its based alloy, the molds which are used in the investment casting process require high chemical inertness, which results in them being very costly and non-recyclable. In order to reduce the cost of these molds, traditionally using yttria as the face coat, two alternative molds are developed in this study with face coat materials of Y2O3-Al2O3 and Y2O3-Al2O3-ZrO2. The slurry properties and chemical inertness of the face coats were evaluated for viscosity, thermal expansion, friability, and phase development. The chemical inertness of these two molds were determined using both the sessile drop test and investment casting to identify the levels of interaction with a Ti-45Al-2Mn-2Nb-0.2B alloy. The results illustrated that the molds using Y2O3-Al2O3 and Y2O3-Al2O3-ZrO2 as the face coats both showed excellent sintering properties and chemical inertness when compared to the yttria face coat. They can consequently be used as two alternative face coats for the investment casting of TiAl alloys.

  6. Cast Process Simulation for the Rapid Tooling.

    NASA Astrophysics Data System (ADS)

    Zhang, Renji; Jiang, Rui; Liu, Yuan; Yan, Yongnian

    1997-03-01

    A major use for RP (Rapid Prototyping) now is in the foundry industry. It is so called RT (Rapid Tooling). Models are used as patterns for sand and plaster casting or used as sacrificial models in investment casting in the RT. In order to improve casting quality, a cast process simulation program for the RT has been made. This simulation depends on analysis of size accuracy parameters. The result could be came back into the CAD forming program. After that a new CAD data have been adopted in RT process. Then the RT technology could have sufficient accuracy in fabrication. Work supported by the Natural Science Foundation of China (NSFC).

  7. Rapid mesh generation for finite element analysis of investment castings

    SciTech Connect

    Lober, R.R.; Bohnhoff, W.J.; Meyers, R.J.

    1992-11-01

    FASTCAST is a Sandia National Laboratories program to produce investment cast prototypical hardware faster by integrating experimental and computational technologies into the casting process. FASTCAST uses the finite element method to characterize the metal flow and solidification processes to reduce uncertainty in the mold design. For the casting process to benefit from finite element analysis, analysis results must be available in a very short time frame. By focusing on the bottleneck of finite element model creation, automated mesh generation can drastically reduce the time span between geometry definition (design) and accurate analysis results. The increased availability of analysis results will diminish the need for trial and error approaches to acquiring production worthy mold and gating systems for investment casting. The CUBIT meshing tool kit is being developed to address the need for rapid mesh generation. CUBIT is being designed to effectively automate the generation of quadrilateral and hexahedral elements. It is a solid-modeler based, two- and three-dimensional preprocessor that prepares solid models for finite element analysis. CUBIT contains several meshing algorithms including two- and three-dimensional mapping, two- and three-dimensional paving (patented), and a general two and one-half dimensional sweeper based upon the plastering algorithm. This paper describes progress in the development of the CUBIT meshing toolkit.

  8. Rapid mesh generation for finite element analysis of investment castings

    SciTech Connect

    Lober, R.R.; Bohnhoff, W.J.; Meyers, R.J.

    1992-01-01

    FASTCAST is a Sandia National Laboratories program to produce investment cast prototypical hardware faster by integrating experimental and computational technologies into the casting process. FASTCAST uses the finite element method to characterize the metal flow and solidification processes to reduce uncertainty in the mold design. For the casting process to benefit from finite element analysis, analysis results must be available in a very short time frame. By focusing on the bottleneck of finite element model creation, automated mesh generation can drastically reduce the time span between geometry definition (design) and accurate analysis results. The increased availability of analysis results will diminish the need for trial and error approaches to acquiring production worthy mold and gating systems for investment casting. The CUBIT meshing tool kit is being developed to address the need for rapid mesh generation. CUBIT is being designed to effectively automate the generation of quadrilateral and hexahedral elements. It is a solid-modeler based, two- and three-dimensional preprocessor that prepares solid models for finite element analysis. CUBIT contains several meshing algorithms including two- and three-dimensional mapping, two- and three-dimensional paving (patented), and a general two and one-half dimensional sweeper based upon the plastering algorithm. This paper describes progress in the development of the CUBIT meshing toolkit.

  9. FInal Report - Investment Casting Shell Cracking

    SciTech Connect

    Von Richards

    2003-12-01

    This project made a significant contribution to the understanding of the investment casting shell cracking problem. The effects of wax properties on the occurrence of shell cracking were demonstrated and can be measured. The properties measured include coefficient of thermal expansion, heating rate and crystallinity of the structure. The important features of production molds and materials properties have been indicated by case study analysis and fractography of low strength test bars. It was found that stress risers in shell cavity design were important and that typical critical flaws were either oversize particles or large pores just behind the prime coat. It was also found that the true effect of fugitive polymer fibers was not permeability increase, but rather a toughening mechanism due to crack deflection.

  10. The effect of investment materials on the surface of cast fluorcanasite glasses and glass-ceramics.

    PubMed

    Bandyopadhyay-Ghosh, Sanchita; Reaney, Ian M; Johnson, Antony; Hurrell-Gillingham, Kathryn; Brook, Ian M; Hatton, P V

    2008-02-01

    Modified fluorcanasite glass-ceramics were produced by controlled two stage heat-treatment of as-cast glasses. Castability was determined using a spiral castability test and the lost-wax method. Specimens were cast into moulds formed from gypsum and phosphate bonded investments to observe their effect on the casting process, surface roughness, surface composition and biocompatibility. Both gypsum and phosphate bonded investments could be successfully used for the lost-wax casting of fluorcanasite glasses. Although the stoichiometric glass composition had the highest castability, all modified compositions showed good relative castability. X-ray diffraction showed similar bulk crystallisation for each glass, irrespective of the investment material. However, differences in surface crystallisation were detected when different investment materials were used. Gypsum bonded investment discs showed slightly improved in vitro biocompatibility than equivalent phosphate bonded investment discs under the conditions used. PMID:17665105

  11. Evaluation of the Inertness of Investment Casting Molds Using Both Sessile Drop and Centrifugal Casting Methods

    NASA Astrophysics Data System (ADS)

    Cheng, Xu; Yuan, Chen; Green, Nick; Withey, Paul

    2013-02-01

    The investment casting process is an economic production method for engineering components in TiAl-based alloys and offers the benefits of a near net-shaped component with a good surface finish. An investigation was undertaken to develop three new face coat systems based on yttria, but with better sintering properties. These face coat systems were mainly based on an yttria-alumina-zirconia system (Y2O3-0.5 wt pct Al2O3-0.5 wt pct ZrO2), an yttria-fluoride system (Y2O3-0.15 wt pct YF3), and an yttria-boride system (Y2O3-0.15 wt pct B2O3). After sintering, the chemical inertness of the face coat was first tested and analyzed using a sessile drop test through the metal wetting behavioral change for each face coat surface. Then, the interactions between the shell and metal were studied by centrifugal investment casting TiAl bars. Although the sintering aids in yttria can decrease the chemical inertness of the face coat, the thickness of the interaction layer in the casting was less than 10 μm; therefore, these face coats still can be possible face coat materials for investment casting TiAl alloys.

  12. Energy Saving Melting andRevert Reduction Technology (E0SMARRT): Predicting Pattern Tooling and Casting Dimension for Investment Casting

    SciTech Connect

    Nick Cannell; Dr. Mark Samonds; Adi Sholapurwalla; Sam Scott

    2008-11-21

    The investment casting process is an expendable mold process where wax patterns of the part and rigging are molded, assembled, shelled and melted to produce a ceramic mold matching the shape of the component to be cast. Investment casting is an important manufacturing method for critical parts because of the ability to maintain dimensional shape and tolerances. However, these tolerances can be easily exceeded if the molding components do not maintain their individual shapes well. In the investment casting process there are several opportunities for the final casting shape to not maintain the intended size and shape, such as shrinkage of the wax in the injection tool, the modification of the shape during shell heating, and with the thermal shrink and distortion in the casting process. Studies have been completed to look at the casting and shell distortions through the process in earlier phases of this project. Dr. Adrian Sabau at Oak Ridge National Labs performed characterizations and validations of 17-4 PH stainless steel in primarily fused silica shell systems with good agreement between analysis results and experimental data. Further tasks provided material property measurements of wax and methodology for employing a viscoelastic definition of wax materials into software. The final set of tasks involved the implementation of the findings into the commercial casting analysis software ProCAST, owned and maintained by ESI Group. This included: o the transfer of the wax material property data from its raw form into separate temperature-dependent thermophysical and mechanical property datasets o adding this wax material property data into an easily viewable and modifiable user interface within the pre-processing application of the ProCAST suite, namely PreCAST o and validating the data and viscoelastic wax model with respect to experimental results

  13. Processing of IN-718 Lattice Block Castings

    NASA Technical Reports Server (NTRS)

    Hebsur, Mohan G.

    2002-01-01

    Recently a low cost casting method known as lattice block casting has been developed by JAM Corporation, Wilmington, Massachusetts for engineering materials such as aluminum and stainless steels that has shown to provide very high stiffness and strength with only a fraction of density of the alloy. NASA Glenn Research Center has initiated research to investigate lattice block castings of high temperature Ni-base superalloys such as the model system Inconel-718 (IN-718) for lightweight nozzle applications. Although difficulties were encountered throughout the manufacturing process , a successful investment casting procedure was eventually developed. Wax formulation and pattern assembly, shell mold processing, and counter gravity casting techniques were developed. Ten IN-718 lattice block castings (each measuring 15-cm wide by 30-cm long by 1.2-cm thick) have been successfully produced by Hitchiner Gas Turbine Division, Milford, New Hampshire, using their patented counter gravity casting techniques. Details of the processing and resulting microstructures are discussed in this paper. Post casting processing and evaluation of system specific mechanical properties of these specimens are in progress.

  14. Integrally cored ceramic investment casting mold fabricated by ceramic stereolithography

    NASA Astrophysics Data System (ADS)

    Bae, Chang-Jun

    Superalloy airfoils are produced by investment casting (IC), which uses ceramic cores and wax patterns with ceramic shell molds. Hollow cored superalloy airfoils in a gas turbine engine are an example of complex IC parts. The complex internal hollow cavities of the airfoil are designed to conduct cooling air through one or more passageways. These complex internal passageways have been fabricated by a lost wax process requiring several processing steps; core preparation, injection molding for wax pattern, and dipping process for ceramic shell molds. Several steps generate problems such as high cost and decreased accuracy of the ceramic mold. For example, costly tooling and production delay are required to produce mold dies for complex cores and wax patterns used in injection molding, resulting in a big obstacle for prototypes and smaller production runs. Rather than using separate cores, patterns, and shell molds, it would be advantageous to directly produce a mold that has the casting cavity and the ceramic core by one process. Ceramic stereolithography (CerSLA) can be used to directly fabricate the integrally cored ceramic casting mold (ICCM). CerSLA builds ceramic green objects from CAD files from many thin liquid layers of powder in monomer, which are solidified by polymerization with a UV laser, thereby "writing" the design for each slice. This dissertation addresses the integrally cored casting ceramic mold (ICCM), the ceramic core with a ceramic mold shell in a single patternless construction, fabricated by ceramic stereolithography (CerSLA). CerSLA is considered as an alternative method to replace lost wax processes, for small production runs or designs too complex for conventional cores and patterns. The main topic is the development of methods to successfully fabricate an ICCM by CerSLA from refractory silica, as well as related issues. The related issues are the segregation of coarse fused silica powders in a layer, the degree of segregation parameter to

  15. The effect of investment type on the fit of cast titanium crowns.

    PubMed

    Mori, T; Jean-Louis, M; Yabugami, M; Togaya, T

    1994-12-01

    In order to determine the best laboratory procedure for titanium crown casting, a set of thermal expansion measurements and casting experiments were carried out using a casting machine (argon arc, pressure difference type) and three different investments, two conventional SiO2 based investments and a new Al2O3/MgO based investment. The thermal expansion measurements involved a cycle of heating and cooling. The relatively low mould temperatures recommended (200 degrees C) or chosen (350 degrees C) for the conventional investments provided zero or negative mould expansion for the compensation of metal shrinkage. Crowns made from these investments exhibited heavy reaction with the mould, and the common cleaning method of sand blasting appeared to be essential. This cleaning process, however, was not adequate for the assessment of casting accuracy as the short sand blasting time (15 s) rapidly altered the fit of the crowns. The metal reacted little with the new investment and the best compensation (0.15 mm discrepancy) for the metal shrinkage, as assessed 'as cast', was achieved when the investment was heated to 950 degrees C and then cooled to the recommended mould temperature (600 degrees C). PMID:7832681

  16. Evaluation of different bonded investments for dental titanium casting.

    PubMed

    Hsu, H C; Kikuchi, H; Yen, S K; Nishiyama, M

    2007-04-01

    The properties of several different investments were investigated including phosphate bonded, magnesia bonded, and alumina cement investments. Measurements included the setting expansion, thermal expansion, and compressive strength of investments, as well as the tensile strength, elongation, Vickers hardness (VHN) and surface roughness of titanium castings. For phosphate bonded investment, the setting expansion after being mixed with its own mixing solution was 2.10%, which was larger than the other investments; the thermal expansion was -0.25% at 200 degrees C, the compressive strength 14 and 5 MPa after heating. For titanium cast in phosphate bonded investment, the hardness on its top surface was 655 Hv, the tensile strength was 379 MPa, the elongation was 19.4%, and the surface roughness was 2.29 microm. Athough the thermal expansion of phosphate bonded investment is small, the setting expansion is large enough to compensate for the shrinkage of titanium castings. As its thermal expansion at T >/= 600 degrees C was constant and its heating-cooling cycle was almost reversible, these two properties can reduce the thermal shock and thus avoid cracking of the investment. PMID:17546420

  17. Evaluation of different bonded investments for dental titanium casting.

    PubMed

    Hsu, H C; Kikuchi, H; Yen, S K; Nishiyama, M

    2005-09-01

    The properties of several different investments were investigated including phosphate bonded, magnesia bonded, and alumina cement investments. Measurements included the setting expansion, thermal expansion, and compressive strength of investments, as well as the tensile strength, elongation, Vickers hardness (VHN) and surface roughness of titanium castings. For phosphate bonded investment, the setting expansion after being mixed with its own mixing solution was 2.10%, which was larger than the other investments; the thermal expansion was -0.25% at 200 degrees C, the compressive strength 14 and 5 MPa after heating. For titanium cast in phosphate bonded investment, the hardness on its top surface was 655 Hv, the tensile strength was 379 MPa, the elongation was 19.4%, and the surface roughness was 2.29 microm. Although the thermal expansion of phosphate bonded investment is small, the setting expansion is large enough to compensate for the shrinkage of titanium castings. As its thermal expansion at T > or = 600 degrees C was constant and its heating-cooling cycle was almost reversible, these two properties can reduce the thermal shock and thus avoid cracking of the investment. PMID:16167110

  18. Predicting Pattern Tooling and Casting Dimensions for Investment Casting, Phase III

    SciTech Connect

    Sabau, Adrian S

    2008-04-01

    Efforts during Phase III focused mainly on the shell-alloy systems. A high melting point alloy, 17-4PH stainless steel, was considered. The experimental part of the program was conducted at ORNL and commercial foundries, where wax patterns were injected, molds were invested, and alloys were poured. Shell molds made of fused-silica and alumino-silicates were considered. A literature review was conducted on thermophysical and thermomechanical properties alumino-silicates. Material property data, which were not available from material suppliers, was obtained. For all the properties of 17-4PH stainless steel, the experimental data available in the literature did not cover the entire temperature range necessary for process simulation. Thus, some material properties were evaluated using ProCAST, based on CompuTherm database. A comparison between the predicted material property data and measured property data was made. It was found that most material properties were accurately predicted only over several temperature ranges. No experimental data for plastic modulus were found. Thus, several assumptions were made and ProCAST recommendations were followed in order to obtain a complete set of mechanical property data at high temperatures. Thermal expansion measurements for the 17-4PH alloy were conducted during heating and cooling. As a function of temperature, the thermal expansion for both the alloy and shell mold materials showed different evolution on heating and cooling. Numerical simulations were performed using ProCAST for the investment casting of 17-4PH stainless steel parts in fused silica molds using the thermal expansion obtained on heating and another one with thermal expansion obtained on cooling. Since the fused silica shells had the lowest thermal expansion properties in the industry, the dewaxing phase, including the coupling between wax-shell systems, was neglected. The shell mold was considered to be a pure elastic material. The alloy dimensions were

  19. Experimental measurement of investment shell properties and use of the data in casting simulation software

    SciTech Connect

    Browne, D.J.; Sayers, K.

    1995-12-31

    This paper describes the development of a systematic program of experimental measurement of relevant properties of mould materials, conducted with the express purpose of generating data for use in casting (filling and solidification) simulation software. In particular the thermophysical properties of the ceramic shell built up for the investment casting process are measured. These properties include specific heat capacity, thermal conductivity, gas permeability, density and surface emissivity. Much of the experimental measurements are taken as a function of temperature, up to the temperature at which moulds are typically fired or preheated. Typical results are presented. The data so generated is then used in a casting simulation model to simulate the investment casting of a prosthetic device. The results of the simulation are presented, and comparisons are made with measurements and observations from an experimental casting of the same part. In this way both the reliability of the data and the accuracy of the filling and solidification model are validated.

  20. Fastcast: Integration and application of rapid prototyping and computational simulation to investment casting

    SciTech Connect

    Maguire, M.C.; Baldwin, M.D.; Atwood, C.L.

    1996-09-01

    The emergence of several rapid prototyping and manufacturing (RP and M) technologies is having a dramatic impact on investment casting. While the most successful of the rapid prototyping technologies are almost a decade old, relatively recent process advances in their application have produced some remarkable success in utilizing their products as patterns for investment castings. Sandia National Laboratories has been developed highly coupled experimental and computational capabilities to examine the investment casting process with the intention of reducing the amount of time required to manufacture castings, and to increase the quality of the finished product. This presentation will begin with process aspects of RP and M pattern production and handling, shell fabrication, burnout, and casting. The emphasis will be on how the use of Stereolithography (SL) or Selective Laser Sintered (SLS) patterns differs from more traditional wax pattern processes. Aspects of computational simulation to couple design, thermal analysis, and mold filling will be discussed. Integration of these topics is probably the greatest challenge to the use of concurrent engineering principles with investment casting. Sandia has conducted several experiments aimed at calibrating computer codes and providing data for input into these simulations. Studies involving materials as diverse as stainless steel and gold have been conducted to determine liquid metal behavior in molds via real time radiography. The application of these experiments to predictive simulations will be described.

  1. Comparative analysis of constraints and caste differences in brain investment among social paper wasps

    PubMed Central

    O'Donnell, Sean; Clifford, Marie; Molina, Yamile

    2011-01-01

    We compared species mean data on the size of functionally distinct brain regions to test the relative rates at which investment in higher-order cognitive processing (mushroom body calyces) versus peripheral sensory processing (optic and antennal lobes) increased with increasing brain size. Subjects were eusocial paper wasps from queen and worker castes of 10 species from different genera. Relative investment in central processing tissue increased with brain size at a higher rate than peripheral structure investment, demonstrating that tissue devoted to higher-order cognitive processing is more constrained by brain size. This pattern held for raw data and for phylogenetically independent contrasts. These findings suggest that there is a minimum necessary investment in peripheral sensory processing brain tissue, with little to gain from additional investment. In contrast, increased brain size provides opportunities to invest in additional higher-order cognitive processing tissue. Reproductive castes differed within species in brain tissue investment, with higher central-to-peripheral brain tissue ratios in queens than in workers. Coupled with previous findings that paper wasp queen, but not worker, brain architecture corresponds to ecological and social variation, queen brain evolution appears to be most strongly shaped by cognitive demands, such as social interactions. These evolutionary patterns of neural investment echo findings in other animal lineages and have important implications, given that a greater investment in higher-order processing has been shown to increase the prevalence of complex and flexible behaviors across the animal kingdom. PMID:21482775

  2. Predicting Pattern Tooling and Casting Dimensions for Investment Casting, Phase II

    SciTech Connect

    Nick Cannell; Adrian S. Sabau

    2005-09-30

    The investment casting process allows the production of complex-shape parts and close dimensional tolerances. One of the most important phases in the investment casting process is the design of the pattern die. Pattern dies are used to create wax patterns by injecting wax into dies. The first part of the project involved preparation of reports on the state of the art at that time for all the areas under consideration (die-wax, wax-shell, and shell-alloy). The primary R&D focus during Phase I was on the wax material since the least was known about it. The main R&D accomplishments during this phase were determination of procedures for obtaining the thermal conductivity and viscoelastic properties of an unfilled wax and validating those procedures. Phase II focused on die-wax and shell-alloy systems. A wax material model was developed based on results obtained during the previous R&D phase, and a die-wax model was successfully incorporated into and used in commercial computer programs. Current computer simulation programs have complementary features. A viscoelastic module was available in ABAQUS but unavailable in ProCAST, while the mold-filling module was available in ProCAST but unavailable in ABAQUS. Thus, the numerical simulation results were only in good qualitative agreement with experimental results, the predicted shrinkage factors being approximately 2.5 times larger than those measured. Significant progress was made, and results showed that the testing and modeling of wax material had great potential for industrial applications. Additional R&D focus was placed on one shell-alloy system. The fused-silica shell mold and A356 aluminum alloy were considered. The experimental part of the program was conducted at ORNL and commercial foundries, where wax patterns were injected, molds were invested, and alloys were poured. It was very important to obtain accurate temperature data from actual castings, and significant effort was made to obtain temperature profiles in

  3. Comparison of Some Neural Network and Multivariate Regression for Predicting Mechanical Properties of Investment Casting

    NASA Astrophysics Data System (ADS)

    Sata, Amit; Ravi, B.

    2014-08-01

    Investment casting enables producing complex shapes with good accuracy and surface finish. A key goal for investment castings used in automobile, aerospace, chemical, biomedical and other critical applications is to be free of internal defects and to possess mechanical properties within the desired range. At present, casting quality is ascertained by destructive testing at the end of production cycle, leading to the possibility of scrapping the entire batch. In this work, the mechanical properties of investment castings have been predicted based on process parameters and chemical composition, by employing artificial neural network (ANN) and multivariate regression (MVR). The data of related process parameters (wax making, shell making, dewaxing, melting etc.), chemical composition of the alloy, and the resulting mechanical properties (ultimate tensile strength, yield strength, and percentage elongation) for 800 heats were collected in an industrial investment casting foundry. Three different ANN models: back propagation, momentum and adaptive, and Levenberg-Marquardt, with varying number of neurons in the hidden layer (from 20 to 45 in steps of 5) were trained using a portion of the data and tested with remaining data. A prediction penalty index (PPI) was developed to compare the relative predictive capability of various neural network and MVR models. It is observed that both ANN and MVR could predict the mechanical properties well, though MVR gave slightly better results. For the ANN model, better results were produced when the number of neurons in the hidden layer was equal or slightly higher than the number of input parameters.

  4. Characterization of Al-Mn particles in AZ91D investment castings

    SciTech Connect

    Lun Sin, S.; Dube, D. Tremblay, R.

    2007-10-15

    Manganese is currently added to Mg-Al alloys in order to improve the corrosion behavior of cast components. A part of this manganese is dissolved in the magnesium matrix and the balance is found as fine Al(Mn,Fe) particles dispersed within castings. For AZ91D specimens prepared using the plaster mould investment casting process, these particles were observed in very large quantity at the surface of castings. These particles were characterized by scanning electron microscopy and electron probe microanalysis. It was found that they consist of Al{sub 8}Mn{sub 5} phase and that their morphology and size depend on local solidification conditions. Their presence at the surface of the castings is related to low solidification rates and reduced thermal gradients at the mould/metal interface.

  5. Development of a New Ferrous Aluminosilicate Refractory Material for Investment Casting of Aluminum Alloys

    NASA Astrophysics Data System (ADS)

    Yuan, Chen; Jones, Sam; Blackburn, Stuart

    2012-12-01

    Investment casting is a time-consuming, labour intensive process, which produces complex, high value-added components for a variety of specialised industries. Current environmental and economic pressures have resulted in a need for the industry to improve current casting quality, reduce manufacturing costs and explore new markets for the process. Alumino-silicate based refractories are commonly used as both filler and stucco materials for ceramic shell production. A new ceramic material, norite, is now being produced based on ferrous aluminosilicate chemistry, having many potential advantages when used for the production of shell molds for casting aluminum alloy. This paper details the results of a direct comparison made between the properties of a ceramic shell system produced with norite refractories and a typical standard refractory shell system commonly used in casting industry. A range of mechanical and physical properties of the systems was measured, and a full-scale industrial casting trial was also carried out. The unique properties of the norite shell system make it a promising alternative for casting aluminum based alloys in the investment foundry.

  6. Investigation of Oxide Bifilms in Investment Cast Superalloy IN100: Part II. Characterization

    NASA Astrophysics Data System (ADS)

    Kaplan, Max A.; Fuchs, Gerhard E.

    2016-05-01

    Oxide bifilms are a proposed casting inclusion reported to have been observed in vacuum investment cast polycrystalline Ni-based superalloys. Ongoing research seeks to determine if current superalloy casting practices can result in the formation of oxide bifilms, and subsequently if it is possible to observe and characterize this phenomenon. The effect of casting atmosphere, turbulence, filtering, hot isostatic pressing, and heat treatment has been investigated to identify the critical parameters that have been reported to result in bifilm formation in Ni-based superalloy IN100. Scanning Auger microscopy (SAM), scanning electron microscopy (SEM), and high-resolution transmission electron microscopy (HR-TEM) were utilized to characterize samples from each casting condition. In situ ultrahigh vacuum Auger fractography did not indicate the presence of bifilms on the fracture behavior of IN100 in any processing condition. SAM analysis identified a sulfur-enriched monolayer on the surface of dendritic casting porosity, and identified heterogeneous Ti oxycarbide inclusions in air cast IN100. SEM analysis also indicated the presence of Ti oxycarbide inclusions in air cast IN100, and determined that these inclusion structures consist of fine blocky external M(Ti, Mo)C carbide enveloping an internal core of alumina. HR-TEM analysis indicated that none of the oxycarbide inclusion interfaces exist as discontinuous unbound interfaces, and that the internal alumina core is an ultra-fine polycrystalline structure.

  7. Investigation of Oxide Bifilms in Investment Cast Superalloy IN100: Part I. Mechanical Properties

    NASA Astrophysics Data System (ADS)

    Fuchs, Gerhard E.; Kaplan, Max A.

    2016-05-01

    Oxide bifilms are a proposed casting inclusion reported to have been observed in vacuum investment cast polycrystalline Ni-based superalloys. Ongoing research seeks to determine if current superalloy casting practices can result in the formation of oxide bifilms, and subsequently if it is possible to observe and characterize this phenomenon. The effects of casting atmosphere, turbulence, filtering, hot isostatic pressing (HIP), and heat treatment have been investigated to identify the critical parameters that have been reported to result in bifilm formation in Ni-based superalloys. Room temperature tensile and room temperature fatigue testing are used to identify the effects of each casting and processing parameter on casting defect formation and the resultant effects on mechanical properties. Characterization of mechanical test specimens seeks to identify the role of casting defects and microstructural features on the fracture mechanisms of the specimen conditions analyzed, and in particular, evidence of bifilm formation and the chemical composition(s) of oxide bifilms. Analyzed tensile and fatigue data did not indicate an influence of bifilms on the tensile or fatigue strength of vacuum processed IN100. Bifilms were not observed, via the characterization methods utilized, to be an active mechanism in tensile or fatigue fracture.

  8. Surface modification of investment cast-316L implants: microstructure effects.

    PubMed

    El-Hadad, Shimaa; Khalifa, Waleed; Nofal, Adel

    2015-03-01

    Artificial femur stem of 316L stainless steel was fabricated by investment casting using vacuum induction melting. Different surface treatments: mechanical polishing, thermal oxidation and immersion in alkaline solution were applied. Thicker hydroxyapatite (HAP) layer was formed in the furnace-oxidized samples as compared to the mechanically polished ones. The alkaline treatment enhanced the precipitation of HAP on the samples. It was also observed that the HAP precipitation responded differently to the different phases of the microstructure. The austenite phase was observed to have more homogeneous and smoother layer of HAP. In addition, the growth of HAP was sometimes favored on the austenite phase rather than on ferrite phase. PMID:25579929

  9. Effect of Slurry Composition on Plate Weight in Ceramic Shell Investment Casting

    NASA Astrophysics Data System (ADS)

    Sidhu, Balwinder Singh; Kumar, Pradeep; Mishra, B. K.

    2008-08-01

    This paper deals with the study of the effect of primary slurry parameters on the plate weight (ceramic retention test) in ceramic shell investment casting process. Four controllable factors of the zircon flour and fused-silica powder based slurries were studied at three levels each by Taguchi’s parametric approach and single-response optimization of plate weight was conducted to identify the main factors controlling its stability. Variations in coating thickness with plate weight were calculated for each slurry and ceramic shell moulds were made on wax plate using primary slurry and coarse fused-silica sand as stucco. The Scanning Electronic Microscopy (SEM) technique has been used to study the surface morphology of zircon flour and fused silca powder particles as well as primary coating (shell surface). X-ray Diffraction (XRD) analysis was done to identify the various phases present in the ceramic slurry coating. Optical profilometer has been used to measure the surface roughness of the shells. The result reveals that the surface condition of shell can be improved by increasing the plate weight, corresponding to higher filler loading in the slurry. Confirmation experiments were conducted at an optimal condition showed that the surface quality of the ceramic shell mould were improved significantly. Castings were produced using Al-7%Si alloy in recommended parameters through ceramic shell investment casting process. Surface roughness of the produced casting were measured and presented in this paper.

  10. A new paradigm: The investment casting cooperative arrangement

    NASA Astrophysics Data System (ADS)

    Mueller, Boyd A.; Monaghan, Philip

    1994-09-01

    Under the leadership of five collaborating companies, the Investment Casting Cooperative Arrangement (ICCA) is in the first two years of a six-year vision that will contribute to maintaining the U.S. competitive advantage in aerospace and, more specifically, aeropropulsion. Equally important is the new paradigm that is being developed for other technologies and industries; it includes the ability of competitive companies to work together as a team in the development of generic technologies that will enhance overall competitiveness. A critical component in the success of a program such as the ICCA is the team's ability to network and interact with other consortia operating with the same technologies so that the efforts are aligned, all resources are being leveraged, and frequent lines of communication have been established at all levels. As a result, the ICCA provides a model framework for genuine interaction among industry, federal laboratories, and universities.

  11. Process development of thin strip steel casting

    SciTech Connect

    Sussman, R.C.; Williams, R.S.

    1990-12-01

    An important new frontier is being opened in steel processing with the emergence of thin strip casting. Casting steel directly to thin strip has enormous benefits in energy savings by potentially eliminating the need for hot reduction in a hot strip mill. This has been the driving force for numerous current research efforts into the direct strip casting of steel. The US Department of Energy initiated a program to evaluate the development of thin strip casting in the steel industry. In earlier phases of this program, planar flow casting on an experimental caster was studied by a team of engineers from Westinghouse Electric corporation and Armco Inc. A subsequent research program was designed as a fundamental and developmental study of both planar and melt overflow casting processes. This study was arranged as several separate and distinct tasks which were often completed by different teams of researchers. An early task was to design and build a water model to study fluid flow through different designs of planar flow casting nozzles. Another important task was mathematically modeling of melt overflow casting process. A mathematical solidification model for the formation of the strip in the melt overflow process was written. A study of the material and conditioning of casting substrates was made on the small wheel caster using the melt overflow casting process. This report discusses work on the development of thin steel casting.

  12. Alloy Shrinkage factors for the investment casting of 17-4PH stainless steel parts

    SciTech Connect

    Sabau, Adrian S; Porter, Wallace D

    2008-01-01

    In this study, the alloy shrinkage factors were obtained for the investment casting of 17-4PH stainless steel parts. For the investment casting process, unfilled wax and fused silica with a zircon prime coat were used for patterns and shell molds, respectively. Dimensions of the die tooling, wax pattern, and casting were measured using a Coordinate Measurement Machine. For all the properties, the experimental data available in the literature did not cover the entire temperature range necessary for process simulation. A comparison between the predicted material property data measured property data is made. It was found that most material properties were accurately predicted over the most of the temperature range of the process. Several assumptions were made in order to obtain a complete set of mechanical property data at high temperatures. Thermal expansion measurements for the 17-4PH alloy were conducted at heating and cooling. As a function of temperature, the thermal expansion for both the alloy and shell mold materials showed different evolution at heating and cooling. Thus, one generic simulation were performed with thermal expansion obtained at heating and another one with thermal expansion obtained at cooling. The alloy dimensions were obtained from numerical simulation results of solidification, heat transfer, and deformation phenomena. As compared with experimental results, the numerical simulation results for the shrinkage factors were slightly over-predicted.

  13. Characterization of oxide bifilms and nonmetallic inclusions in investment cast superalloy IN100

    NASA Astrophysics Data System (ADS)

    Kaplan, Max A.

    Oxide bifilms are a proposed casting inclusion reported to have been observed in vacuum investment cast polycrystalline Ni-base superalloys. This investigation seeks to determine if current superalloy casting methods can result in the formation of oxide bifilms, and subsequently if it is possible to observe and characterize this phenomenon. The effect of casting atmosphere, turbulence, filtering, HIP, and heat treatment have been investigated to identify the critical parameters that may result in bifilm formation in Ni-based superalloy IN100. Bifilms have been reported to impact mechanical behavior and fracture characteristics of cast superalloys, therefore tensile and fatigue testing was used in an effort to identify the effects of each casting and processing parameter on bifilm formation. Characterization of mechanical test specimens sought to identify the role of bifilms in the fracture mechanics of the conditions utilized, as well as the prevalence of bifilm formation and the chemical composition(s) of oxide bifilms. The characterization methods used were SEM, EDS, SAM, AES, STEM, BF-TEM, and HR-TEM. Tensile and fatigue test data did not indicate an influence of bifilms on the mechanical behavior of IN100, however there was a considerable impact due to the formation of Ti oxycarbide inclusions. Statistical analysis confirmed that vacuum and argon cast material under conditions expected to cause abundant bifilm formation exhibit no measurable debit to mechanical properties as compared to conditions anticipated to prevent/remediate bifilms. Bifilms were not identified during metallographic characterization or fractographic analysis of mechanical test specimens. In-situ ultrahigh vacuum Auger fractography also did not indicate the presence of bifilms in the fracture behavior of IN100 in any processing condition. However, a sulfur-enriched monolayer has been identified on the surface of dendritic casting porosity, as characterized by Auger analysis. Metallographic

  14. Vacuum investment cast PH13-8Mo corrosion resistant steel. (SAE standard)

    SciTech Connect

    1991-07-01

    An industry-wide interest has arisen with regards to the properties and capabilities of investment cast PH 13-8Mo corrosion resistant steel. Specifically of interest are the structural applications in the aerospace industry for this product heat treated to the H1000 condition. The objective of this AMEC cooperative test program was to generate and compile useful data for aerospace structural evaluation of investment cast PH 13-8Mo heat treated to H1000. The determination was made of overall mechanical properties, fatigue, fracture toughness, and crack growth data along with basic microstructural evaluation of the investment cast material. The evaluation of mechanical property variations between cast and machined tensile specimens and evaluation of microstructural constituents. PH 13-8Mo, H1000 investment castings for use in the aerospace industry is included.

  15. FRICTION STIR MICROSTRUCTURAL MODIFICATION OF INVESTMENT CAST F357

    SciTech Connect

    Jana, s.; Mishra, Rajiv S.; Chou, H. N.; Herling, Darrell R.

    2007-02-09

    A hypoeutectic Al-Si alloy has been friction stir processed in this study using various run parameter combinations. Tensile test results indicate at least three times improvement in ductility value over as-cast T6 condition because of refinement in Si particle size. Si particle size and shape has been quantified and correlated with mechanical properties. Tool rotation rate seems to have the most significant effect on properties. Higher tool rotation rate resulted in more uniform and homogeneous microstructure though some anomaly is observed at very high tool rotation rate.

  16. Investigation of the effects of cooling rate on the microstructure of investment cast biomedical grade Co alloys

    NASA Astrophysics Data System (ADS)

    Kaiser, R.; Browne, D. J.; Williamson, K.

    2012-01-01

    The objective of this work is to determine the microstructural characteristics of investment cast cobalt alloy as the cross-sectional area is varied, thus changing the local effective cooling rates and solidification times. The extent of published work on the as-cast properties of cobalt alloys is minimal. The primary aim of this work is therefore to extend knowledge of the behaviour of such alloys as they solidify, which will influence the design of new products as well as the industrial optimisation of the casting process. Wedge-shaped parts were cast from a biomedical grade cobalt alloy employing the method of lost wax investment casting. Analytical techniques such as optical microscopy, image analysis and microhardness testing were used to characterise the as-cast parts. Parameters studied include variations in grain structure, nature of the columnar and equiaxed zones and the spread of porosity (both shrinkage and gas). Changes in microstructure were compared to microhardness values obtained. The solidification profile of the alloy through the prototype cast component was investigated based on measurement of the dendrite arm spacings. A discussion on the physical phenomena controlling the microstructural variations is presented.

  17. Rapid tooling for functional prototyping of metal mold processes: Literature review on cast tooling

    SciTech Connect

    Baldwin, M.D.; Hochanadel, P.W.

    1995-11-01

    This report is a literature review on cast tooling with the general focus on AISI H13 tool steel. The review includes processing of both wrought and cast H13 steel along with the accompanying microstructures. Also included is the incorporation of new rapid prototyping technologies, such as Stereolithography and Selective Laser Sintering, into the investment casting of tool steel. The limiting property of using wrought or cast tool steel for die casting is heat checking. Heat checking is addressed in terms of testing procedures, theories regarding the mechanism, and microstructural aspects related to the cracking.

  18. Effect of porosity on ductility variation in investment cast 17-4PH.

    SciTech Connect

    Wright, Robert D.; Kilgo, Alice C.; Grant, Richard P.; Crenshaw, Thomas B.; Susan, Donald Francis

    2005-02-01

    The stainless steel alloy 17-4PH contains a martensitic microstructure and second phase delta ({delta}) ferrite. Strengthening of 17-4PH is attributed to Cu-rich precipitates produced during age hardening treatments at 900-1150 F (H900-H1150). For wrought 17-4PH, the effects of heat treatment and microstructure on mechanical properties are well-documented [for example, Ref. 1]. Fewer studies are available on cast 17-4PH, although it has been a popular casting alloy for high strength applications where moderate corrosion resistance is needed. Microstructural features and defects particular to castings may have adverse effects on properties, especially when the alloy is heat treated to high strength. The objective of this work was to outline the effects of microstructural features specific to castings, such as shrinkage/solidification porosity, on the mechanical behavior of investment cast 17-4PH. Besides heat treatment effects, the results of metallography and SEM studies showed that the largest effect on mechanical properties is from shrinkage/solidification porosity. Figure 1a shows stress-strain curves obtained from samples machined from castings in the H925 condition. The strength levels were fairly similar but the ductility varied significantly. Figure 1b shows an example of porosity on a fracture surface from a room-temperature, quasi-static tensile test. The rounded features represent the surfaces of dendrites which did not fuse or only partially fused together during solidification. Some evidence of local areas of fracture is found on some dendrite surfaces. The shrinkage pores are due to inadequate backfilling of liquid metal and simultaneous solidification shrinkage during casting. A summary of percent elongation results is displayed in Figure 2a. It was found that higher amounts of porosity generally result in lower ductility. Note that the porosity content was measured on the fracture surfaces. The results are qualitatively similar to those found by

  19. The improvement of aluminium casting process control by application of the new CRIMSON process

    NASA Astrophysics Data System (ADS)

    Dai, X.; Jolly, M.; Zeng, B.

    2012-07-01

    All The traditional foundry usually not only uses batch melting where the aluminium alloys are melted and held in a furnace for long time, but also uses the gravity filling method in both Sand Casting Process (SCP) and Investment Casting Process (ICP). In the gravity filling operation, the turbulent behaviour of the liquid metal causes substantial entrainment of the surface oxide films which are subsequently trapped into the liquid and generate micro cracks and casting defects. In this paper a new CRIMSON process is introduced which features instead of gravity filling method, using the single shot up-casting method to realize the rapid melting and rapid filling mould operations which reduce the contact time between the melt and environment thus reducing the possibility of defect generation. Another advantage of the new process is the drastic reduction of energy consumption due to shortened melting and filling time. Two types of casting samples from SCP and ICP were compared with the new process. The commercial software was used to simulate the filling and solidification processes of the casting samples. The results show that the new process has a more improved behaviour during filling a mould and solidification than the two conventional casting processes.

  20. The Effects of Casting Porosity on the Tensile Behavior of Investment Cast 17-4PH Stainless Steel

    NASA Astrophysics Data System (ADS)

    Susan, D. F.; Crenshaw, T. B.; Gearhart, J. S.

    2015-08-01

    The effect of casting porosity on the mechanical behavior of investment cast 17-4PH stainless steel was studied as well as the effect of heat treatment on the alloy's sensitivity to casting defects. Interdendritic porosity, formed during solidification and shrinkage of the alloy, reduces the yield strength and ultimate tensile strength roughly in proportion to the reduction in load bearing cross-section. The effects of casting porosity on ductility (% strain, % reduction in area) are more severe, in agreement with research on other alloy systems. In this study, 10% porosity reduced the ductility of 17-4PH stainless steel by almost 80% for the high-strength H925 condition. Tensile testing at -10°C (263 K) further reduces the alloy ductility with and without pores present. In the lower strength H1100 condition, the ductility is higher than the H925 condition, as expected, and somewhat less sensitive to porosity. By measuring the area % porosity on the fracture surface of tensile specimens, the trend in failure strain versus area % porosity was obtained and analyzed using two methods: an empirical approach to determine an index of defect susceptibility with a logarithmic fit and an analytical approach based on the constitutive stress-strain behavior and critical strain concentration in the vicinity of the casting voids. The applicability of the second method depends on the amount of non-uniform strain (necking) and, as such, the softer H1100 material did not correlate well to the model. The behavior of 17-4PH was compared to previous work on cast Al alloys, Mg alloys, and other cast materials.

  1. Casting a Wider Net: Investing in "Distributed Learning."

    ERIC Educational Resources Information Center

    Dede, Christopher

    1998-01-01

    Information technology is a cost-effective investment in public schools only with innovations in pedagogy, curriculum, assessment, and school organization. This article examines the impracticality of equipping every student with high performance computing and communication and proposes a "distributed learning" model, orchestrating educational…

  2. Solidification modeling of continuous casting process

    NASA Astrophysics Data System (ADS)

    Lerner, V. S.; Lerner, Y. S.

    2005-04-01

    The aim of the present work was to utilize a new systematic mathematical-informational approach based on informational macrodynamics (IMD) to model and optimize the casting process, taking as an example horizontal continuous casting (HCC). The IMD model takes into account the interrelated thermal, diffusion, kinetic, hydrodynamic, and mechanical effects that are essential for the given casting process. The optimum technological process parameters are determined by the simultaneous solution of problems of identification and optimal control. The control functions of the synthesized optimal model are found from the extremum of the entropy functional having a particular sense of an integrated assessment of the continuous cast bar physicochemical properties. For the physical system considered, the IMD structures of the optimal model are connected with controllable equations of nonequilibrium thermodynamics. This approach was applied to the HCC of ductile iron, and the results were compared with experimental data and numerical simulation. Good agreement was confirmed between the predicted and practical data, as well as between new and traditional methods.

  3. Investment casting of {gamma}-TiAl-based alloys: Microstructure and data base for gas turbine applications

    SciTech Connect

    Wagner, R.; Appel, F.; Dogan, B.

    1995-12-31

    Investment casting is regarded as an economic processing technology for the production of {gamma}-TiAl based components for gas turbine applications. Near net-shape parts can be cast such that they are free from pores and flaws after adequate `HIP`ping. The inhomogeneous cast microstructure which results from locally varying cooling rates (e.g. in the root and foil of a blade), however, is often retained even after heat-treatments necessary to achieve a balance of properties for a given application. Appropriate modifications of the alloy chemistry may lead to an improved microstructural homogeneity in the cast parts. Data bases of properties (tensile properties, creep, fatigue and rupture strength, fracture and impact toughness, oxidation and corrosion resistance) which are relevant for potential gas turbine applications have been assessed for different cast {gamma}-TiAl alloys with different microstructures. These are compared with corresponding properties of nickel-based and iron-based superalloys {gamma}-TiAl is competing with for substitution.

  4. Castability and surface hardness of titanium cast plates obtained from experimental phosphate-bonded silica investment molds.

    PubMed

    Takahashi, J; Zhang, J Z; Okazaki, M

    1993-12-01

    The effect of 12 different experimental compositions of phosphate-bonded SiO2 investments was examined on cast pure titanium. The mold temperature was 600 degrees C and the casting was conducted with an argon-arc melting and pressure casting machine. Castability was evaluated by the volume of casting porosity, which was calculated from the volume of wax pattern (15 mm x 15 mm x 1.5 mm), the weight of cast plate and the specific density of pure titanium. The existence of inner casting porosities was confirmed by an X-ray non-destructive inspection instrument. Cast plates made in molds with cristobalite had significantly lower castability and higher surface hardness than those in molds with quartz as a refractory material. Cast plates in molds (quartz-cristobalite mixtures) with 20% binder had lower surface hardness and fewer casting porosities than those in molds with 10% binder. PMID:8004919

  5. The Impact of Ceramic Shell Strength on Hot Tearing during Investment Casting

    SciTech Connect

    Norouzi, Saeid; Farhangi, Hassan

    2011-01-17

    The effect of ceramic shell strength on hot tearing susceptibility during solidification was inspected practicing investment casting of the cobalt-base superalloy samples with the same casting conditions, but different ceramic shell systems. Results showed that the lower the ceramic shell strength upon using polymer additives, the lower the hindered contraction rate, and the lower the hindered contraction rate, the smaller the hot tearing tendency. Optical microscopy and electron microscopy scanning revealed that the hot tear propagated along the last solidified interdendritic phase, and that the hot tear surface had two major modes: (1) the ductile region in the outer layer; and (2) the inner region of liquid embrittlement.

  6. Process for slip casting textured tubular structures

    DOEpatents

    Steinlage, Greg A.; Trumble, Kevin P.; Bowman, Keith J.

    2002-01-01

    A process for centrifugal slip casting a textured hollow tube. A slip made up of a carrier fluid and a suspended powder is introduced into a porous mold which is rotated at a speed sufficient to create a centrifugal force that forces the slip radially outward toward the inner surface of the mold. The suspended powder, which is formed of particles having large dimensional aspect ratios such as particles of superconductive BSCCO, settles in a textured fashion radially outward toward the mold surface. The carrier fluid of the slip passes by capillary action radially outward around the settled particles and into the absorbent mold. A layer of mold release material is preferably centrifugally slip cast to cover the mold inner surface prior to the introduction of the BSCCO slip, and the mold release layer facilitates removal of the BSCCO greenbody from the mold without fracturing.

  7. Fabrication of low-cost, cementless femoral stem 316L stainless steel using investment casting technique.

    PubMed

    Baharuddin, Mohd Yusof; Salleh, Sh-Hussain; Suhasril, Andril Arafat; Zulkifly, Ahmad Hafiz; Lee, Muhammad Hisyam; Omar, Mohd Afian; Abd Kader, Ab Saman; Mohd Noor, Alias; A Harris, Arief Ruhullah; Abdul Majid, Norazman

    2014-07-01

    Total hip arthroplasty is a flourishing orthopedic surgery, generating billions of dollars of revenue. The cost associated with the fabrication of implants has been increasing year by year, and this phenomenon has burdened the patient with extra charges. Consequently, this study will focus on designing an accurate implant via implementing the reverse engineering of three-dimensional morphological study based on a particular population. By using finite element analysis, this study will assist to predict the outcome and could become a useful tool for preclinical testing of newly designed implants. A prototype is then fabricated using 316L stainless steel by applying investment casting techniques that reduce manufacturing cost without jeopardizing implant quality. The finite element analysis showed that the maximum von Mises stress was 66.88 MPa proximally with a safety factor of 2.39 against endosteal fracture, and micromotion was 4.73 μm, which promotes osseointegration. This method offers a fabrication process of cementless femoral stems with lower cost, subsequently helping patients, particularly those from nondeveloped countries. PMID:24404766

  8. Application of Rapid Prototyping to the Investment Casting of Test Hardware (MSFC Center Director's Discretionary Fund Final Report, Project No. 98-08)

    NASA Technical Reports Server (NTRS)

    Cooper, K. G.; Wells, D.

    2000-01-01

    Investment casting masters of a selected propulsion hardware component, a fuel pump housing, were rapid prototyped on the several processes in-house, along with the new Z-Corp process acquired through this project. Also, tensile samples were prototyped and cast using the same significant parameters. The models were then shelled in-house using a commercial grade zircon-based slurry and stucco technique. Next, the shelled models were fired and cast by our in-house foundry contractor (IITRI), with NASA-23, a commonly used test hardware metal. The cast models are compared by their surface finish and overall appearance (i.e., the occurrence of pitting, warping, etc.), as well as dimensional accuracy.

  9. The effect of microstructure on the thermal fatigue resistance of investment cast and wrought AISI H13 hot work die steel

    SciTech Connect

    Hochanadel, P.W.; Edwards, G.R.; Maguire, M.C.; Baldwin, M.D.

    1995-07-01

    Variable thickness plate investment castings of AISI H13 hot work die steel were pour and characterized in the as-cast and heat treated conditions. The characterization included light microscopy and mechanical testing. Wrought samples of standard and premium grade H13 steel were heat treated and characterized similarly for comparison. Microstructural differences were observed in as-cast samples poured to different section thicknesses. Dendrite cell size and carbide morphology constituted the most prominent microstructural differences observed. After a full heat treatment, however, Microstructural differences between the wrought material and cast materials were slight regardless of section thickness. The mechanical properties of the cast and heat treated material proved similar to the properties of the standard heat treated wrought material. A thermal fatigue testing unit was designed and built to correlate the heat checking susceptibility of AISI H13 steel to its processing and consequent microstructural condition. Surface hardness decreased significantly with thermal cycling, and heat checking was noticed in as few as 50 cycles. Thermal softening and thermal fatigue susceptibility were quantified and discussed relative to the microstructural conditions created by processing and heat treatment. It was found that the premium grade wrought H13 steel provided the best overall resistance to heat checking; however, the heat-treat cast and as-cast H13 tool steel (made from standard grade wrought H13 tool steel) provided comparable resistance to heat checking in terms Of area fraction of heat checking and maximum crack length.

  10. Cryogenic Fracture Toughness Evaluation of an Investment Cast Al-Be Alloy for Structural Applications

    NASA Technical Reports Server (NTRS)

    Gamwell, W. R.; McGill, P. B.

    2006-01-01

    Aluminum-Beryllium metal matrix composite materials are useful due to their desirable performance characteristics for aerospace applications. Desirable characteristics of this material includes light-weight, dimensional stability, stiffness, good vibration damping characteristics, low coefficient of thermal expansion, and workability, This material is 3.5 times stiffer and 22% lighter than conventional aluminum alloys. electro-optical systems, advanced sensor and guidance components for flight and satellite systems, components for light-weight high-performance aircraft engines, and structural components for helicopters. Aluminum-beryllium materials are now available in the form of near net shape investment castings. In this materials properties characterization study, the cryogenic tensile and fracture properties of an investment casting alloy, Beralcast 363, were determined. Tensile testing was performed at 21 C (70 F), -73.3 C (-100 F), -195.5 C (-320 F) and -252.8 C (-423 F), and fracture (K(sub lc) and da/dN) testing was performed at -73.3 C (-100 F), -195.5 C (-320 F) and -252.8 C (-423 F). Their use is attractive for weight critical structural applications such as advanced

  11. Marginal accuracy of nickel chromium copings fabricated by conventional and accelerated casting procedures, produced with ringless and metal ring investment procedures: A comparative in vitro study

    PubMed Central

    Alex, Deepa; Shetty, Y. Bharath; Miranda, Glynis Anita; Prabhu, M. Bharath; Karkera, Reshma

    2015-01-01

    Background: Conventional investing and casting techniques are time-consuming and usually requires 2–4 h for completion. Accelerated nonstandard, casting techniques have been reported to achieve similar quality results in significantly less time, namely, in 30–40 min. During casting, it is essential to achieve compensation for the shrinkage of solidifying alloy by investment expansion. The metal casting ring restricts the thermal expansion of investment because the thermal expansion of the ring is lesser than that of the investment. The use of casting ring was challenged with the introduction of the ringless technique. Materials and Methods: A total of 40 test samples of nickel chromium (Ni-Cr) cast copings were obtained from the patterns fabricated using inlay casting wax. The 20 wax patterns were invested using metal ring and 20 wax patterns were invested using the ringless investment system. Of both the groups, 10 samples underwent conventional casting, and the other 10 underwent accelerated casting. The patterns were casted using the induction casting technique. All the test samples of cast copings were evaluated for vertical marginal gaps at four points on the die employing a stereo optical microscope. Results: The vertical marginal discrepancy data obtained were tabulated. Mean and standard deviations were obtained. Vertical discrepancies were analyzed using analysis of variance and Tukey honestly significantly different. The data obtained were found to be very highly significant (P < 0.001). Mean vertical gap was the maximum for Group II (53.64 μm) followed by Group IV (47.62 μm), Group I (44.83 μm) and Group III (35.35 μm). Conclusion: The Ni-Cr cast copings fabricated with the conventional casting using ringless investment system showed significantly better marginal fit than that of cast copings fabricated from conventional and accelerated casting with metal ring investment and accelerated casting using ringless investment since those copings had

  12. Hanford's Simulated Low Activity Waste Cast Stone Processing

    SciTech Connect

    Kim, Young

    2013-08-20

    Cast Stone is undergoing evaluation as the supplemental treatment technology for Hanford’s (Washington) high activity waste (HAW) and low activity waste (LAW). This report will only cover the LAW Cast Stone. The programs used for this simulated Cast Stone were gradient density change, compressive strength, and salt waste form phase identification. Gradient density changes show a favorable outcome by showing uniformity even though it was hypothesized differently. Compressive strength exceeded the minimum strength required by Hanford and greater compressive strength increase seen between the uses of different salt solution The salt waste form phase is still an ongoing process as this time and could not be concluded.

  13. Development of a thin steel strip casting process. Final report

    SciTech Connect

    Williams, R.S.

    1994-04-01

    This is a comprehensive effort to develop direct strip casting to the point where a pilot scale program for casting carbon steel strip could be initiated. All important aspects of the technology were being investigated, however the program was terminated early due to a change in the business strategy of the primary contractor, Armco Inc. (focus to be directed at specialty steels, not low carbon steel). At termination, the project was on target on all milestones and under budget. Major part was casting of strip at the experiment casting facility. A new caster, capable of producing direct cast strip of up to 12 in. wide in heats of 1000 and 3000 lb, was used. A total of 81 1000-1200 lb heats were cast as well as one test heat of 3000 lb. Most produced strip of from 0.016 to 0.085 in. thick. Process reliability was excellent for short casting times; quality was generally poor from modern hot strip mill standards, but the practices necessary for good surface quality were identified.

  14. Mould filling of Ag-Pd-Cu-Au and Ag-Zn-Sn-In alloy castings made using a rapidly prepared gypsum-bonded investment material.

    PubMed

    Shimizu, Hiroshi; Inoue, Shoko; Miyauchi, Hideaki; Watanabe, Kouichi; Takahashi, Yutaka

    2008-12-01

    Mandibular premolar-shaped wax patterns of full crowns with a marginal angle of 300 were prepared. Two semiprecious alloys were cast using a rapidly prepared gypsum-bonded investment material or a conventional gypsum-bonded investment. A precise impression was taken and cut into four segments. Scanning electron microscopy was used to evaluate the mould filling of each segment. The mould filling of the silver-palladium-copper-gold alloy was worse than that of the silver-zinc-tin-indium alloy. The mould filling of both alloys cast with the rapidly prepared gypsum-bonded investment material was superior to that using the conventional investment. PMID:19177729

  15. Application of particle method to the casting process simulation

    NASA Astrophysics Data System (ADS)

    Hirata, N.; Zulaida, Y. M.; Anzai, K.

    2012-07-01

    Casting processes involve many significant phenomena such as fluid flow, solidification, and deformation, and it is known that casting defects are strongly influenced by the phenomena. However the phenomena complexly interacts each other and it is difficult to observe them directly because the temperature of the melt and other apparatus components are quite high, and they are generally opaque; therefore, a computer simulation is expected to serve a lot of benefits to consider what happens in the processes. Recently, a particle method, which is one of fully Lagrangian methods, has attracted considerable attention. The particle methods based on Lagrangian methods involving no calculation lattice have been developed rapidly because of their applicability to multi-physics problems. In this study, we combined the fluid flow, heat transfer and solidification simulation programs, and tried to simulate various casting processes such as continuous casting, centrifugal casting and ingot making. As a result of continuous casting simulation, the powder flow could be calculated as well as the melt flow, and the subsequent shape of interface between the melt and the powder was calculated. In the centrifugal casting simulation, the mold was smoothly modeled along the shape of the real mold, and the fluid flow and the rotating mold are simulated directly. As a result, the flow of the melt dragged by the rotating mold was calculated well. The eccentric rotation and the influence of Coriolis force were also reproduced directly and naturally. For ingot making simulation, a shrinkage formation behavior was calculated and the shape of the shrinkage agreed well with the experimental result.

  16. Process improvement as an investment: Measuring its worth

    NASA Technical Reports Server (NTRS)

    Mcgarry, Frank; Jeletic, Kellyann

    1993-01-01

    This paper discusses return on investment (ROI) generated from software process improvement programs. It details the steps needed to compute ROI and compares these steps from the perspective of two process improvement approaches: the widely known Software Engineering Institute's capability maturity model and the approach employed by NASA's Software Engineering Laboratory (SEL). The paper then describes the specific investments made in the SEL over the past 18 years and discusses the improvements gained from this investment by the production organization in the SEL.

  17. [Evaluation of cervical gaps in complete metal crowns cast in alternative silver-tin alloys. Relationship to investing techniques].

    PubMed

    Vecchio, G M; Pretti, E; Vaz, R R; Zaniquelli, O

    1990-01-01

    The purpose of this study was to evaluate cervical mistifing of casting full metal crowns according to investment techniques using commercial available alloys made from silver stannum. Fifteen metal full crowns were obtained through stainless steel die with full crowns preparation, included into three groups as follows: conventional technique, vacuum technique and pressure technique. Readings of cervical disagreement were made through a comparing microscope increased 45 x and each crown was measured in 4 different regions (vestibular, lingual mesial and distal). This way it was verified which of the techniques proposed would balance the casting shrinkage for the silver-stannum alloy used. From the results obtained we conclude that the best cercical adaptation was the one got through pressure technique. PMID:2135769

  18. AMCC casting development, volume 2

    NASA Technical Reports Server (NTRS)

    1995-01-01

    PCC successfully cast and performed nondestructive testing, FPI and x-ray, on seventeen AMCC castings. Destructive testing, lab analysis and chemical milling, was performed on eleven of the castings and the remaining six castings were shipped to NASA or Aerojet. Two of the six castings shipped, lots 015 and 016, were fully processed per blueprint requirements. PCC has fully developed the gating and processing parameters of this part and feels the part could be implemented into production, after four more castings have been completed to ensure the repeatability of the process. The AMCC casting has been a technically challenging part due to its size, configuration, and alloy type. The height and weight of the wax pattern assembly necessitated the development of a hollow gating system to ensure structural integrity of the shell throughout the investment process. The complexity in the jacket area of the casting required the development of an innovative casting technology that PCC has termed 'TGC' or thermal gradient control. This method of setting up thermal gradients in the casting during solidification represents a significant process improvement for PCC and has been successfully implemented on other programs. The alloy, JBK75, is a relatively new alloy in the investment casting arena and required our engineering staff to learn the gating, processing, and dimensional characteristics of the material.

  19. Effect of Process Parameters, Casting Thickness, and Alloys on the Interfacial Heat-Transfer Coefficient in the High-Pressure Die-Casting Process

    NASA Astrophysics Data System (ADS)

    Guo, Zhi-Peng; Xiong, Shou-Mei; Liu, Bai-Cheng; Li, Mei; Allison, John

    2008-12-01

    The heat transfer at the metal-die interface is believed to have great influence on the solidification process and cast structure of the high-pressure die-casting (HPDC) process. The present article focused on the effects of process parameters, casting thickness, and alloys on the metal-die interfacial heat-transfer coefficient (IHTC) in the HPDC process. Experiment was carried out on a cold-chamber die-casting machine with two casting alloys AM50 and ADC12. A special casting, namely, “step-shape” casting, was used and cast against a H13 steel die. The IHTC was determined using an inverse approach based on the temperature measurements inside the die. Results show that the IHTC is different at different steps and changes as the solidification of the casting proceeds. Process parameters only influence the IHTC in its peak value, and for both AM50 and ADC12 alloys, a greater fast shot velocity leads to a greater IHTC peak value at steps 1 and 2. The initial die surface temperature has a more prominent influence on the IHTC peak values at the thicker steps, especially step 5. Results also show that a closer contact between the casting and die could be achieved when the casting alloy is ADC12 instead of AM50, which consequently leads to a higher IHTC.

  20. Characterization of Spray Lubricants for the Die Casting Process

    SciTech Connect

    Sabau, Adrian S

    2008-01-01

    During the die casting process, lubricants are sprayed in order to cool the dies and facilitate the ejection of the casting. The cooling effects of the die lubricant were investigated using Thermogravimetric analysis (TGA), heat flux sensors (HFS), and infrared imaging. The evolution of the heat flux and pictures taken using a high speed infrared camera revealed that lubricant application was a transient process. The short time response of the HFS allows the monitoring and data acquisition of the surface temperature and heat flux without additional data processing. A similar set of experiments was performed with deionized water in order to assess the lubricant effect. The high heat flux obtained at 300 C was attributed to the wetting and absorbant properties of the lubricant. Pictures of the spray cone and lubricant flow on the die were also used to explain the heat flux evolution.

  1. Lab experiments on the innovative rapid thick strip casting process

    NASA Astrophysics Data System (ADS)

    Nagy, Richard; Senk, Dieter

    2012-05-01

    Rapid thick strip casting (RTSC) by Anton Hulek, Inventmetall®, is an innovative concept for the production of hot strips with a final as-cast thickness of about 25 mm before rolling. The innovation of the mechanism consists in a vertical mould performing a caterpillar motion. This moving mould has an unconventional parallelogram-shaped cross-section. The conventional rectangular shape is formed in the shaping machine, which is placed straight below the mould. Further elements of the technology are state-of-the-art. For the investigation of this new casting system theoretical calculations were complemented with practical experiments. The investigation focused mainly on two key aspects: the characteristics of the mould and the shaping process. For the practical analysis a static mould with three pairs of elements in laboratory scale was developed and commissioned by the Dept. of Ferrous Metallurgy @ RWTH Aachen University. The shaping experiments were carried out in model scale with two different materials and in variable boundary conditions. The results of these experiments delivered important mechanical as well as thermal informations about the casting system.

  2. Fabrication and characterization of cast magnesium matrix composites by vacuum stir casting process

    NASA Astrophysics Data System (ADS)

    Gui, Manchang; Li, Peiyong; Han, Jianmin

    2003-04-01

    A vacuum stir casting process is developed to produce SiCp reinforced cast magnesium matrix composites. This process can eliminate the entrapment of external gas onto melt and oxidation of magnesium during stirring synthesis. Two composites with Mg-Al9Zn and Mg-Zn5Zr alloys as matrices and 15 vol.% SiC particles as reinforcement are obtained. The microstructure and mechanical properties of the composites and the unreinforced alloys in as-cast and heat treatment conditions are analyzed and evaluated. In 15 vol.% SiCp reinforced Mg-Al9Zn alloy-based composite (Mg-Al9Zn/15SiCp), SiC particles distribute homogenously in the matrix and are well bonded with magnesium. In 15 vol.% SiCp reinforced Mg-Zn5Zr alloy-based composite (Mg-Zn5Zr/15SiCp), some agglomerations of SiC particles can be seen in the microstructure. In the same stirring process conditions, SiC reinforcement is more easily wetted by magnesium in the Mg-Al9Zn melt than in the Mg-Zn5Zr melt. The significant improvement in yield strength and elastic modulus for two composites has been achieved, especially for the Mg-Al9Zn/15SiCp composite in which yield strength and elastic modulus increase 112 and 33%, respectively, over the unreinforced alloy, and increase 24 and 21%, respectively, for the Mg-Zn5Zr/15SiCp composite. The strain-hardening behaviors of the two composites and their matrix alloys were analyzed based on the microstructure characteristics of the materials.

  3. Process modelings and simulations of heavy castings and forgings

    NASA Astrophysics Data System (ADS)

    Li, Dianzhong; Sun, Mingyue; Wang, Pei; Kang, Xiuhong; Fu, Paixian; Li, Yiyi

    2013-05-01

    The Materials Process Modeling Division, IMR, CAS has been promoting for more than 10 years research activities on modeling and experimental studies on heavy castings and forgings. In this report, we highlight some selected achievements and impacts in this area: To satisfy domestic strategic requirements, such as nuclear and hydraulic power, marine projects and high speed rail, we have developed a number of casting and forging technologies, which combine advanced computing simulations, X-ray real time observation techniques and industrial-scaled trial experiments. These technologies have been successfully applied in various industrial areas and yielded a series of scientific and technological breakthroughs and innovation. Important examples of this strategic research include the hot-processing technologies of the Three Gorge water turbine runner, marine crankshaft manufacturers, backup rolls for hot rolling mills and the production of hundreds-ton steel ingot.

  4. Liquid Metal Processing and Casting Experiences at the U.S. Department of Energy's Albany Research Center

    SciTech Connect

    Jablonski, Paul D.; Turner, Paul C.

    2005-09-01

    In this paper we will discuss some of the early pioneering work as well as some of our more recent research. The Albany Research Center (ARC) has been involved with the melting and processing of metals since it was established in 1942. In the early days, hardly anything was known about melting refractory or reactive metals and as such, virtually everything had to be developed in-house. Besides the more common induction heated air-melt furnaces, ARC has built and/or utilized a wide variety of furnaces including vacuum arc remelt ingot and casting furnaces, cold wall induction furnaces, electric arc furnaces, cupola furnaces and reverberatory furnaces. The melt size of these furnaces range from several grams to a ton or more. We have used these furnaces to formulate custom alloys for wrought applications as well as for such casting techniques as spin casting, investment casting and lost foam casting among many. Two early spin-off industrializations were Wah Chang (wrought zirconium alloys for military and commercial nuclear applications) and Oremet (both wrought and cast Ti). Both of these companies are now part of the ATI Allegheny Ludlum Corporation.

  5. Investigation on the Interface Characteristics of Al/Mg Bimetallic Castings Processed by Lost Foam Casting

    NASA Astrophysics Data System (ADS)

    Jiang, Wenming; Li, Guangyu; Fan, Zitian; Wang, Long; Liu, Fuchu

    2016-05-01

    The lost foam casting (LFC) process was used to prepare the A356 aluminum and AZ91D magnesium bimetallic castings, and the interface characteristics of the reaction layer between aluminum and magnesium obtained by the LFC process were investigated in the present work. The results indicate that a uniform and compact interface between the aluminum and magnesium was formed. The reaction layer of the interface with an average thickness of approximately 1000 μm was mainly composed of Al3Mg2 and Al12Mg17 intermetallic compounds, including the Al3Mg2 layer adjacent to the aluminum insert, the Al12Mg17 middle layer, and the Al12Mg17 + δ eutectic layer adjacent to the magnesium base. Meanwhile, the Mg2Si intermetallic compound was also detected in the reaction layer. An oxide film mainly containing C, O, and Mg elements generated at the interface between the aluminum and magnesium, due to the decomposed residue of the foam pattern, the oxidations of magnesium and aluminum alloys as well as the reaction between the magnesium melt and the aluminum insert. The microhardness tests show that the microhardnesses at the interface were obviously higher than those of the magnesium and aluminum base metals, and the Al3Mg2 layer at the interface had a high microhardness compared with the Al12Mg17 and Al12Mg17 + δ eutectic layers, especially the eutectic layer.

  6. Nucleation in Al Alloys Processed By MCDC Casting

    NASA Astrophysics Data System (ADS)

    Prasada Rao, A. K.

    2015-06-01

    Present work confines itself to discuss the mechanism responsible for the grain refinement of the melt conditioned direct-chill cast aluminum alloys. It has been found that the Al alloys processed by this process undergo grain refinement irrespective of their chemical composition. The forced convection caused during this process led to dendrite fragmentation which enhances the heterogeneous nucleation and result in grain refinement. It is suggested that owing to their favorable lattice matching with α-Al, these fragments serve as potent nuclei for α-Al grains.

  7. Minimization of Macrosegregation in DC Cast Ingots Through Jet Processing

    NASA Astrophysics Data System (ADS)

    Wagstaff, Samuel R.; Allanore, Antoine

    2016-06-01

    With an increase in demand for aluminum alloys, industrial suppliers are seeking to increase the size and speed of casting processes. Unfortunately operating the existing Direct-Chill (DC) process in such conditions tends to enhance metallurgical defects. Perhaps the most recognized of these defects is macrosegregation, whose effects are permanent once the material is solidified. In order to facilitate the expansion of the DC process without increasing the presence of macrosegregation, a novel jet mixing method to distribute the liquid metal is presented. The governing equations for this process are derived and the operating parameters necessary to minimize the centerline macrosegregation are predicted. The results of commercial-scale tests are presented, validating the predictive equations and performance of this process.

  8. Vacuum forming of thermoplastic sheet results in low-cost investment casting patterns

    NASA Technical Reports Server (NTRS)

    Clarke, A. E., Jr.

    1964-01-01

    Vacuum forming of a sheet of thermoplastic material around a mandrel conforming to the shape of the finished object provides a pattern for an investment mold. The thickness of the metal part is determined by the thickness of the plastic pattern.

  9. Investment casting using multi-jet modelling patterns: the thermogravimetric analysis of visijet® SR200 UV curable acrylate plastic

    NASA Astrophysics Data System (ADS)

    Hafsa, M. N.; Ibrahim, M.; Sharif, S.

    2013-12-01

    Rapid Prototyping (RP) technology is actively studied to be implemented in Investment Casting (IC) process. Nowadays RP techniques are studied for their feasibility as IC master patterns, in terms of pattern collapsibility and drainage during burnout. The purpose of the study is to determine the characteristic of Visijet® SR200 acrylate material during burnout process. Traditional IC patterns made from wax have properties that limit their application in precision casting, especially for parts with thin geometries that readily break or deform when handled or dipped in the refractory slurry. Furthermore, it is not economical when producing a small number of parts. Non wax patterns fabricated for IC process, revealed ceramic shell cracking due to excessive thermal expansions, incomplete collapsibility of pattern during burnout, residual ash and poor surface finish. Thermogravimetric analysis (TGA) was used to measured the weight loss of acrylate material as the temperature was increased. TGA measured the change of material's mass as it is heated. It represents the decomposition temperature after being subjected to varying temperatures, as well as the amount of residual ash. In this experiment, the temperature range was from 20°C to 700°C with 5°C increment. Experiment results show the values of material's optimum reaction temperature and decomposing temperature of Visijet® SR200 acrylate. The percentages of remaining materials were also monitored throughout the process to obtain the amount of residual ash. All of the temperature values obtained is a resemblance for the actual burnout process and can be used as references.

  10. Influence of Refiner in ZA-12 Alloys During Centrifugal Casting Process

    NASA Astrophysics Data System (ADS)

    Jyothi, P. N.; Shailesh, Rao A.; Jagath, M. C.; Channakeshavalu, K.

    2014-05-01

    The behavior of the molten melt plays a predominant role in determining the quality cast product. In continuous casting, addition of refiner 1% (Al+Ti+B2) onto the molten metal increases its mechanical properties as a result of the nucleation within the process. In this article, the effect of refiners in the centrifugal casting process was studied. Eutectic ZA-12 alloys were taken for our experiment and cast at various rotational speeds (400 rpm, 600 rpm, and 800 rpm) with and without the addition of refiners. Rather than increase in the solidification rate as in continuous casting, these refiners diminish the solidification rate, which in turn forms an irregular-shaped cast tube. The microstructure and hardness for the entire cast specimen were discussed finally.

  11. Thermo-Metallurgical Modeling of Nodular Cast Iron Cooling Process

    NASA Astrophysics Data System (ADS)

    Carazo, Fernando D.; Dardati, Patricia M.; Celentano, Diego J.; Godoy, Luis A.

    2012-12-01

    A new numerical model to describe the microstructural evolution of a eutectic nodular cast iron during its cooling is presented. In particular, equiaxial solidification assuming an independent nucleation of austenite and graphite nodules is considered. In this context, the austenite has dendritic growth whereas the graphite grows with a spherical shape. After solidification occurs, the model assumes that the graphite nodules present in the cast iron continue growing since the carbon content in austenite decreases. Once the stable eutectoid temperature is reached, the alloy undergoes the austenite-ferrite transformation. The nucleation of the ferrite takes place at the contour of the spherical graphite nodules where austenite has low carbon concentration. A ferrite shell surrounding the graphite nodules is formed afterward by means of a process governed by carbon diffusion. Then, a ferrite-pearlite competitive transformation occurs when the temperature is below the metastable temperature. This thermo-metallurgical model is discretized and solved by means of the finite element method. The model allows the computation of cooling curves, fraction evolution for each component, and size and distribution of graphite nodules. The present numerical results are compared with experiments using standardized Quick-cup-type cups, and satisfactory numerical predictions of the final microstructure and cooling curves are achieved.

  12. Engineering scale demonstration of a prospective Cast Stone process

    SciTech Connect

    Cozzi, A.; Fowley, M.; Hansen, E.; Fox, K.; Miller, D.; Williams, M.

    2014-09-30

    This report documents an engineering-scale demonstration with non-radioactive simulants that was performed at SRNL using the Scaled Continuous Processing Facility (SCPF) to fill an 8.5 ft container with simulated Cast Stone grout. The Cast Stone formulation was chosen from the previous screening tests. Legacy salt solution from previous Hanford salt waste testing was adjusted to correspond to the average composition generated from the Hanford Tank Waste Operation Simulator (HTWOS). The dry blend materials, ordinary portland cement (OPC), Class F fly ash, and ground granulated blast furnace slag (GGBFS or BFS), were obtained from Lafarge North America in Pasco, WA. Over three days, the SCPF was used to fill a 1600 gallon container, staged outside the facility, with simulated Cast Stone grout. The container, staged outside the building approximately 60 ft from the SCPF, was instrumented with x-, y-, and z-axis thermocouples to monitor curing temperature. The container was also fitted with two formed core sampling vials. For the operation, the targeted grout production rate was 1.5 gpm. This required a salt solution flow rate of approximately 1 gpm and a premix feed rate of approximately 580 lb/h. During the final day of operation, the dry feed rate was increased to evaluate the ability of the system to handle increased throughput. Although non-steady state operational periods created free surface liquids, no bleed water was observed either before or after operations. The final surface slope at a fill height of 39.5 inches was 1-1.5 inches across the 8.5 foot diameter container, highest at the final fill point and lowest diametrically opposed to the fill point. During processing, grout was collected in cylindrical containers from both the mixer discharge and the discharge into the container. These samples were stored in a humid environment either in a closed box proximal to the container or inside the laboratory. Additional samples collected at these sampling points

  13. Numerical Simulation of Horizontal Continuous Casting Process of C194 Copper Alloy

    NASA Astrophysics Data System (ADS)

    Huang, Guojie; Xie, Shuisheng; Cheng, Lei; Cheng, Zhenkang

    2007-05-01

    Horizontal Continuous Casting (H.C.C) is an important method to cast C194 copper ingot. In this paper, numerical simulation is adopted to investigate the casting process in order to optimize the H.C.C technical parameters, such as the casting temperature, casting speed and cooling intensity. According to the numerical results, the reasonable parameters are that the casting temperature is between 1383K˜1463K, the casting speed is between 7.2m/h˜10.8m/h and the speed of cooling water is between 3.6m/s˜4.6m/s. The results of numerical simulation provide the significant reference to the subsequent experiments.

  14. Fast Docking on Graphics Processing Units via Ray-Casting

    PubMed Central

    Khar, Karen R.; Goldschmidt, Lukasz; Karanicolas, John

    2013-01-01

    Docking Approach using Ray Casting (DARC) is structure-based computational method for carrying out virtual screening by docking small-molecules into protein surface pockets. In a complementary study we find that DARC can be used to identify known inhibitors from large sets of decoy compounds, and can identify new compounds that are active in biochemical assays. Here, we describe our adaptation of DARC for use on Graphics Processing Units (GPUs), leading to a speedup of approximately 27-fold in typical-use cases over the corresponding calculations carried out using a CPU alone. This dramatic speedup of DARC will enable screening larger compound libraries, screening with more conformations of each compound, and including multiple receptor conformations when screening. We anticipate that all three of these enhanced approaches, which now become tractable, will lead to improved screening results. PMID:23976948

  15. Thermal casting process for the preparation of membranes

    DOEpatents

    Caneba, G.T.M.; Soong, D.S.

    1985-07-10

    Disclosed is a method for providing anisotropic polymer membrane from a binary polymer/solvent solution using a thermal inversion process. A homogeneous binary solution is cast onto a support and cooled in such a way as to provide a differential in cooling rate across the thickness of the resulting membrane sheet. Isotropic or anisotropic structures of selected porosities can be produced, depending on the initial concentration of polymer in the selected solvent and on the extent of the differential in cooling rate. This differential results in a corresponding gradation in pore size. The method may be modified to provide a working skin by applying a rapid, high-temperature pulse to redissolve a predetermined thickness of the membrane at one of its faces and then freezing the entire structure.

  16. Simulation of solidification process for billet with ϕ350mm section, continuous casted

    NASA Astrophysics Data System (ADS)

    Ardelean, E.; Lăscuţoni, A.; Ardelean, M.; Socalici, A.; Hepuţ, T.

    2016-02-01

    The quality of continuous casting product depends both on the quality of the steel, and on technological parameters adopted during the casting and how solidification of billets is conducted. A simulation of the solidifying process is very useful in the industrial casting practice, providing specialists with information about the phenomena during the process and the manner in which certain parameters may vary in order to obtain the desired effects. This paper presents a two-dimensional simulation model that can be used in the continuous casting process, when micro-coolers are used in order to control thermal regime during solidification.

  17. Heat treatment of investment cast PH 13-8 Mo stainless steel; Part 2: Isothermal aging kinetics

    SciTech Connect

    Robino, C.V.; Cieslak, M.J. . Physical and Joining Metallurgy Dept.); Hochanadel, P.W.; Edwards, G.R. . Dept. of Metallurgical and Materials Engineering)

    1994-04-01

    The hardening response of investment cast PH 13-8 Mo stainless steel has been evaluated by hardness measurements following aging in the temperature range normally specified for this alloy (510 C to 593 C). A new relationship between fraction transformed and hardness was developed, and analysis of the data in terms of the kinetics of precipitation, in a manner similar to that frequently applied to other precipitation-hardenable martensitic steels, yielded low time exponents and a low value for the apparent activation energy. The values of the time exponents were 0.49, 0.37, 0.56, and 0.53 at 510 C, 538 C, 566 C, and 593 C, respectively, and that for the apparent activation energy was 139 kJ/mole. As has been proposed for other maraging type steels, these estimates suggest that [beta]-NiAl precipitates along or near dislocations and that growth of the precipitates is dominated by dislocation pipe diffusion. However, these predictions were neither supported nor refuted by transmission electron microscopy (TEM) because of difficulties in imaging the [beta]-NiAl precipitates at the aging times and temperatures used. Further, analysis of the data using the formalism of Wert and Zener for the growth of precipitates with interfering diffusion fields indicated that the estimates of fraction transformed from hardness data are not fully appropriate for maraging type steels. Consideration of the nature of the Avrami analysis and the electron microscopy results suggests that other phenomena, including dislocation recovery and reversion of martensite to austenite, occur at rates sufficient to convolute the Avrami analysis. It is further suggested that these results cast doubt on the fundamental implications of previous analyses of precipitation kinetics in age-hardening martensitic steels.

  18. Integrated Computational Materials Engineering and Modelling of Shape Casting Processes - Needs, Benefits, Limitations and Hurdles

    NASA Astrophysics Data System (ADS)

    Schneider, M. C.; Sturm, J. C.; Schaefer, W.; Hepp, E.; Gurevich, V.

    2015-06-01

    In this paper, the industrial needs and potential benefits of ICME for shape castings are described from the point of view of a commercial provider of casting process simulation tools. At the same time, the paper addresses the challenges, limitations, and hurdles regarding the extent to which ICME is or can be adopted on an industrial scale for shape cast components. The discussion is backed by concrete examples illustrating the advantages and limitations of integrating models and simulation in the design chain of cast components, in the design and analysis of the processing route of a casting, as well as over the different length scales through which the structures and corresponding behaviorof the cast material are determined. The biggest impact of the ICME approach will only be apparent when the increased accuracy or level of detail provided by the methodology is truly necessary, because it leads to changes in design decisions for the product or manufacturing process.

  19. Heat treatment of investment cast PH 13-8 Mo stainless steel: Part I. Mechanical properties and microstructure

    NASA Astrophysics Data System (ADS)

    Hochanadel, P. W.; Edwards, G. R.; Robino, C. V.; Cieslak, M. J.

    1994-04-01

    The microstructure of investment cast PH 13-8 Mo stainless steel heat-treated to various conditions was studied using light and electron microscopy, electron probe microanalysis, and Mössbauer spectroscopy. The mechanical properties were investigated by using uniaxial tensile testing, hardness testing, and Charpy impact testing. The Β-NiAl strengthening precipitates, though detectable by electron diffraction, were difficult to resolve by transmission electron microscopy (TEM) in specimens aged at low temperatures (566 °C and below). A high dislocation density was observed in the lath martensitic structure. The higher strength and lower ductility observed at low aging temperatures was attributed to both the high dislocation density and the precipitation of Β-NiAl. When samples were aged at high temperatures (> 566 °C), a lower dislocation density and a reverted austenite fraction on the order of 15 pct were observed. Spherical Β-NiAl precipitates were observed in the overaged condition. The decrease in strength and corresponding increase in ductility observed in samples aged at temperatures above 566 °C were attributed to the reverted austenite and recovery. Mechanical properties were improved when the homogenizing temperature and time were increased. Electron probe microanalysis quantified the increased homogeneity realized by increasing homogenizing temperature and time. Elimination of the refrigeration step, which normally follows the solution treatment, did not degrade the mechanical properties. Mössbauer spectroscopy showed only minor decreases in the fraction of retained austenite when refrigeration followed the solution treatment.

  20. Melting and casting processes for high-temperature intermetallics

    SciTech Connect

    Sen, Subhayu; Stefanescu, D.M. )

    1991-05-01

    Most of the metallic systems thus far identified as promising from the commercial viewpoint are composed of elements which are either susceptible to oxidation, such as Al, or highly reactive, such as Ti; these characteristics entail the use of such melting and casting techniques as vacuum-induction melting, vacuum-arc remelting, electroslag refining, plasma-arc melting, spray casting, and directional solidification. Spray casting is noteworthy both in its ability to produce near-net-shape components and its inherent reduction of the oxygen and hydrogen pickup which has been associated with the embrittlement of aluminides. 24 refs.

  1. Software Analytical Instrument for Assessment of the Process of Casting Slabs

    SciTech Connect

    Franek, Zdenek; Kavicka, Frantisek; Stetina, Josef; Masarik, Milos

    2010-06-15

    The paper describes the original proposal of ways of solution and function of the program equipment for assessment of the process of casting slabs. The program system LITIOS was developed and implemented in EVRAZ Vitkovice Steel Ostrava on the equipment of continuous casting of steel (further only ECC). This program system works on the data warehouse of technological parameters of casting and quality parameters of slabs. It enables an ECC technologist to analyze the course of casting melt and with using statistics methods to set the influence of single technological parameters on the duality of final slabs. The system also enables long term monitoring and optimization of the production.

  2. Feasibility of cold rolling titanium strip cast by the plasma melt overflow process

    SciTech Connect

    Gaspar, T.A.; Sukonnik, I.M.; Bird, R.K.; Brewer, W.D.

    1995-12-31

    A new fabrication method tailored specifically for titanium alloys and intermetallics combined direct strip casting and cold rolling to produce foil products by completely eliminating hot working steps. Titanium strips 0.4-mm- to 0.7-mm-thick and 100-mm-wide were cast by the plasma melt overflow process. The cast strips were cold rolled to 0.15-mm-thick, fully dense foils. The effect of thermal and mechanical treatments on the microstructure of the cast strip was investigated. The cold rolled foils were characterized by measurement of average surface roughness, chemical composition, gas content and tensile properties.

  3. Asymptotic analysis of surface waves in continuous strip casting processes

    NASA Astrophysics Data System (ADS)

    Kluwick, Alfred; Scheichl, Stefan

    2000-09-01

    This paper presents a two-dimensional analysis of surface waves possibly emerging in a specific open channel flow with continuous solidification, i.e. the fluid consisting of molten material is cooled from below and solidifies. In modern metallurgical engineering such processes are of importance for the strip casting of steel and other metals. The study is based on the assumption that the wavelengths are large compared to the characteristic depth of the melt but small compared to the solidification length. Within the framework of a weakly nonlinear theory the use of the Euler equations supplemented with the appropriate boundary conditions at the solidification front and the free surface yields two Korteweg-de Vries equations with varying coefficients, which govern the propagation of the waves. However, the adopted form of the asymptotic expansions ceases to be valid as the point of complete solidification is approached, where the displacements at the free boundary and the depth of the melt are of the same order. Thus, a separate investigation for this region is carried out in order to describe the further evolution of the surface waves and its influence on the final shape of the fully solidified metal sheet.

  4. Report of Separate Effects Testing for Modeling of Metallic Fuel Casting Process

    SciTech Connect

    Crapps, Justin M.; Galloway, Jack D.; Decroix, David S.; Korzekwa, David A.; Aikin, Robert M. Jr.; Unal, Cetin; Fielding, R.; Kennedy, R

    2012-06-29

    In order to give guidance regarding the best investment of time and effort in experimental determination of parameters defining the casting process, a Flow-3D model of the casting process was used to investigate the most influential parameters regarding void fraction of the solidified rods and solidification speed for fluid flow parameters, liquid heat transfer parameters, and solid heat transfer parameters. Table 1 summarizes the most significant variables for each of the situations studied. A primary, secondary, and tertiary effect is provided for fluid flow parameters (impacts void fraction) and liquid heat transfer parameters (impacts solidification). In Table 1, the wetting angle represents the angle between the liquid and mold surface as pictured in Figure 1. The viscosity is the dynamic viscosity of the liquid and the surface tension is the property of the surface of a liquid that allows it to resist an external force. When only considering solid heat transfer properties, the variations from case to case were very small. Details on this conclusion are provided in the section considering solid heat transfer properties. The primary recommendation of the study is to measure the fluid flow parameters, specifically the wetting angle, surface tension, and dynamic viscosity, in order of importance, as well as the heat transfer parameters latent heat and specific heat of the liquid alloy. The wetting angle and surface tension can be measured simultaneously using the sessile drop method. It is unclear whether there is a temperature dependency in these properties. Thus measurements for all three parameters are requested at 1340, 1420, and 1500 degrees Celsius, which correspond to the minimum, middle, and maximum temperatures of the liquid alloy during the process. In addition, the heat transfer coefficient between the mold and liquid metal, the latent heat of transformation, and the specific heat of the liquid metal all have strong influences on solidification. These

  5. Modern processes of production of thin sheets and strips by continuous casting

    NASA Astrophysics Data System (ADS)

    Smirnov, A. N.

    2012-06-01

    The history of the development of producing thin sheets and strips by continuous casting methods is considered. The mechanism of this sheet formation during casting of steel in a two-roll continuous caster is described. The advantages of this process over the corresponding traditional technologies are discussed.

  6. Heat treatment of investment cast PH 13-8 Mo stainless steel: Part II. Isothermal aging kinetics

    NASA Astrophysics Data System (ADS)

    Robino, C. V.; Cieslak, M. J.; Hochanadel, P. W.; Edwards, G. R.

    1994-04-01

    The hardening response of investment cast PH 13-8 Mo stainless steel has been evaluated by hardness measurements following aging in the temperature range normally specified for this alloy (510 °C to 593 °C). A new relationship between fraction transformed and hardness was developed, and analysis of the data in terms of the kinetics of precipitation, in a manner similar to that frequently applied to other precipitation-hardenable martensitic steels, yielded low time exponents and a low value for the apparent activation energy. The values of the time exponents were 0.49, 0.37, 0.56, and 0.53 at 510 °C, 538 °C, 566 °C, and 593 °C, respectively, and that for the apparent activation energy was 139 kJ/mole. As has been proposed for other maraging type steels, these estimates suggest that Β-NiAl precipitates along or near dislocations and that growth of the precipitates is dominated by dislocation pipe diffusion. However, these predictions were neither supported nor refuted by transmission electron microscopy (TEM) because of difficulties in imaging the Β-NiAl precipitates at the aging times and temperatures used. Further, analysis of the data using the formalism of Wert and Zener for the growth of precipitates with interfering diffusion fields indicated that the estimates of fraction transformed from hardness data are not fully appropriate for maraging type steels. Consideration of the nature of the Avrami analysis and the electron microscopy results suggests that other phenomena, including dislocation recovery and reversion of martensite to austenite, occur at rates sufficient to convolute the Avrami analysis. It is further suggested that these results cast doubt on the fundamental implications of previous analyses of precipitation kinetics in age-hardening martensitic steels. Although the Avrami analysis was found not to provide a tenable description of the precipitation kinetics, it does provide a reasonable methodology for portrayal of the hardening response

  7. Numerical simulation of the solidification processes of copper during vacuum continuous casting

    NASA Astrophysics Data System (ADS)

    Tsai, D. C.; Hwang, W. S.

    2012-03-01

    A numerical simulation method is used to analyze the microstructure evolution of 8-mm-diameter copper rods during the vacuum continuous casting (VCC) process. The macro-microscopic coupling method is adopted to develop a temperature field model and a microstructure prediction model. The effects of casting parameters, including casting speed, pouring temperature, cooling rate, and casting dimension on the location and shape of the solid-liquid (S/L) interface and solidified microstructure are considered. Simulation results show that the casting speed has a large effect on the position and shape of the S/L interface and grain morphology. With an increase of casting speed, the shape of the S/L interface changes from a planar shape into an elliptical shape or a narrow, pear shape, and the grain morphology indicates a change from axial growth to axial-radial growth or completely radial growth. The simulation predictions agree well with the microstructure observations of cast specimens. Further analysis of the effects of other casting parameters on the position and shape of the S/L interface reveals that the casting dimension has more influence on the position and shape of the S/L interface and grain morphology than do pouring temperature and cooling rate. The simulation results can be summarized to obtain a discriminant of shape factor (η), which defines the shape of the S/L interface and grain morphology.

  8. Multiscale Modeling and Simulation of Directional Solidification Process of Turbine Blade Casting with MCA Method

    NASA Astrophysics Data System (ADS)

    Xu, Qingyan; Zhang, Hang; Qi, Xiang; Liu, Baicheng

    2014-04-01

    Nickel-based superalloy turbine blade castings are widely used as a key part in aero engines. However, due to the complex manufacturing processes, the complicated internal structure, and the interaction between different parts of the turbine blade, casting defects, such as stray grains, often happen during the directional solidification of turbine blade castings, which causes low production yield and high production cost. To improve the quality of the directionally solidified turbine blade castings, modeling and simulation technique has been employed to study the microstructure evolution as well as to optimize the casting process. In this article, a modified cellular automaton (MCA) method was used to simulate the directional solidification of turbine blade casting. The MCA method was coupled with macro heat transfer and micro grain growth kinetics to simulate the microstructure evolution during the directional solidification. In addition, a ray tracing method was proposed to calculate the heat transfer, especially the heat radiation of multiple blade castings in a Bridgman furnace. A competitive mechanism was incorporated into the grain growth model to describe the grain selection behavior phenomena of multiple columnar grains in the grain selector. With the proposed models, the microstructure evolution and related defects could be simulated, while the processing parameters optimized and the blade casting quality guaranteed as well. Several experiments were carried out to validate the proposed models, and good agreement between the simulated and experimental results was achieved.

  9. Numerical simulation of casting process to assist in defects reduction in complex steel tidal power component

    NASA Astrophysics Data System (ADS)

    Guo, E. J.; Zhao, S. C.; Wang, L. P.; Wu, T.; Xin, B. P.; Tan, J. J.; Jia, H. L.

    2016-03-01

    In order to reduce defects and improve casting quality, ProCAST software is performed to study the solidification process of discharge bowl. Simulated results of original casting process show that the hot tearing is serious at the intersection of blades and outer or inner rings. The shrinkage porosity appears at the bottom of discharge bowl and the transition area of wall thickness. Based on the formation mechanisms of the defects, the structure of chills attached on the outer surface of discharge bowl casting is optimized. The thickness of chills ranges from 25mm to 35mm. The positions of chills corresponded to the outer surface of the T-shaped parts. Compared to the original casting design (without chills), the hot tearing and shrinkage porosity of the discharge bowl are greatly improved with addition of chills.

  10. Multiphysics modeling of the steel continuous casting process

    NASA Astrophysics Data System (ADS)

    Hibbeler, Lance C.

    This work develops a macroscale, multiphysics model of the continuous casting of steel. The complete model accounts for the turbulent flow and nonuniform distribution of superheat in the molten steel, the elastic-viscoplastic thermal shrinkage of the solidifying shell, the heat transfer through the shell-mold interface with variable gap size, and the thermal distortion of the mold. These models are coupled together with carefully constructed boundary conditions with the aid of reduced-order models into a single tool to investigate behavior in the mold region, for practical applications such as predicting ideal tapers for a beam-blank mold. The thermal and mechanical behaviors of the mold are explored as part of the overall modeling effort, for funnel molds and for beam-blank molds. These models include high geometric detail and reveal temperature variations on the mold-shell interface that may be responsible for cracks in the shell. Specifically, the funnel mold has a column of mold bolts in the middle of the inside-curve region of the funnel that disturbs the uniformity of the hot face temperatures, which combined with the bending effect of the mold on the shell, can lead to longitudinal facial cracks. The shoulder region of the beam-blank mold shows a local hot spot that can be reduced with additional cooling in this region. The distorted shape of the funnel mold narrow face is validated with recent inclinometer measurements from an operating caster. The calculated hot face temperatures and distorted shapes of the mold are transferred into the multiphysics model of the solidifying shell. The boundary conditions for the first iteration of the multiphysics model come from reduced-order models of the process; one such model is derived in this work for mold heat transfer. The reduced-order model relies on the physics of the solution to the one-dimensional heat-conduction equation to maintain the relationships between inputs and outputs of the model. The geometric

  11. Advances in multi-scale modeling of solidification and casting processes

    NASA Astrophysics Data System (ADS)

    Liu, Baicheng; Xu, Qingyan; Jing, Tao; Shen, Houfa; Han, Zhiqiang

    2011-04-01

    The development of the aviation, energy and automobile industries requires an advanced integrated product/process R&D systems which could optimize the product and the process design as well. Integrated computational materials engineering (ICME) is a promising approach to fulfill this requirement and make the product and process development efficient, economic, and environmentally friendly. Advances in multi-scale modeling of solidification and casting processes, including mathematical models as well as engineering applications are presented in the paper. Dendrite morphology of magnesium and aluminum alloy of solidification process by using phase field and cellular automaton methods, mathematical models of segregation of large steel ingot, and microstructure models of unidirectionally solidified turbine blade casting are studied and discussed. In addition, some engineering case studies, including microstructure simulation of aluminum casting for automobile industry, segregation of large steel ingot for energy industry, and microstructure simulation of unidirectionally solidified turbine blade castings for aviation industry are discussed.

  12. PREFACE: MCWASP XIV: International Conference on Modelling of Casting, Welding and Advanced Solidification Processes

    NASA Astrophysics Data System (ADS)

    Yasuda, H.

    2015-06-01

    The current volume represents contributed papers of the proceedings of the 14th international conference on ''Modeling of Casting, Welding and Advanced Solidification Processes (MCWASP XIV)'', Yumebutai International Conference Center, Awaji island, Hyogo, Japan on 21 - 26 June, 2016. The first conference of the series 'Modeling of Casting, Welding and Advanced Solidification Processes (MCWASP)' was started up in 1980, and this is the 14th conference. The participants are more than 100 scientists from industry and academia, coming from 19 countries. In the conference, we have 5 invited, 70 oral and 31 poster presentations on different aspects of the modeling. The conference deals with various casting processes (Ingot / shape casting, continuous casting, direct chill casting and welding), fundamental phenomena (nucleation and growth, dendritic growth, eutectic growth, micro-, meso- and macrostructure formation and defect formation), coupling problems (electromagnetic interactions, application of ultrasonic wave), development of experimental / computational methods and so on. This volume presents the cutting-edge research in the modeling of casting, welding and solidification processes. I would like to thank MAGMA Giessereitechnologie GmbH, Germany and SCSK Corporation, Japan for supporting the publication of contributed papers. Hideyuki Yasuda Conference Chairman Department of Materials Science and Engineering, Kyoto University Japan

  13. Continuous Casting of Single Crystal Ingots by the O.C.C. Process

    NASA Astrophysics Data System (ADS)

    Ohno, A.

    1986-01-01

    To prevent the nucleation of crystals on the mold wall in the continuous casting of metals, a heated mold that maintained that temperature above the solidification temperature of the cast metal was used instead of the conventional cold mold. The cooling of the ingot was conducted outside of the mold. Heat was conducted axially along the ingot from the mold zone to the cooling zone. The principle of the O.C.C. (Ohno Continuous Casting) Process® was applied to the horizontal casting and vertical (upward) casting of wire and platelike ingots of Sn and Al. The ingots consisted of a completely unidirectionally solidified structure. It was possible to obtain a long single crystal ingot as a result of the growth competition of crystals.

  14. Thermo-mechanical phenomena in high speed continuous casting processes

    NASA Astrophysics Data System (ADS)

    Park, Joong Kil

    Thermo-mechanical phenomena during continuous thin slab casting have been studied with the objectives of understanding the mechanism of mold crack formation, and the effect of mold design upon the mechanical behavior of the stand. To achieve these goals, several finite element models have been developed in conjunction with a series of industrial plant trials. First, an investigation of mold crack formation in thin slab casting was undertaken to elucidate the mechanism by which cracks develop and to evaluate possible solutions to the problem. Three-dimensional finite-element thermal-stress models were developed to predict temperature, distortion, and residual stress in thin-slab casting molds, comparing funnel-shaped to parallel molds. Mold wall temperatures were obtained from POSCO in Korea and analyzed to determine the corresponding heat-flux profiles in thin-slab molds. This data was utilized in an elastic-visco-plastic analysis to investigate the deformation of the molds in service for the two different mold shapes. The results of a metallurgical investigation of mold samples containing cracks were used together with the results of the mathematical models, to determine mechanisms and to suggest solutions for the formation of mold cracks. Large cyclic inelastic strains were found in the funnel transition region just below the meniscus, due to the slightly higher temperature at that location. The cracks appear to have propagated by thermal fatigue caused by major level fluctuations. Next, two-dimensional thermo-elastic-visco-plastic analysis was performed for a horizontal slice of the solidifying strand, which moves vertically down the mold during casting. The model calculates the temperature distributions, the stresses and the strains in the solidifying shell, and the air gap between the casting mold and the solidifying strand. Model predictions were verified with an analytical solution and plant trials that were carried out during billet casting at POSCO. The

  15. The microstructures of strip-cast low-carbon steels and their response to thermal processing

    NASA Astrophysics Data System (ADS)

    Shiang, L.-T.; Wray, P. J.

    1989-07-01

    The as-cast microstructure and its modification when subjected to heat treatment is examined for strip-cast low carbon steels. The local solidification rate in the twin-roll strip casting process is estimated to. be 590 to 850 °C/s, and the primary and secondary dendrite arm spacings are approximately 17 to 25 and 10 μm, respectively. The as-cast structure is predominantly Widmanstätten ferrite and, thereby, differs from the conventional hot-rolled sheet. It is suggested that the as-cast morphology is a result of the large initial austenite grain size and the cooling rate and is not a unique characteristic of rapid solidification of strip casting. By restricting the austenite grain size and cooling rate, polygonal ferrite morphology probably can be produced during strip casting. The response to heat treatment depends on the presence of aluminum; with a moderate amount of aluminum, the A1N precipitates in the as-cast structure inhibit the subsequent grain boundary movement and may affect the subsequent recrystallization behavior.

  16. Numerical simulation of the casting process of titanium tooth crowns and bridges.

    PubMed

    Wu, M; Augthun, M; Wagner, I; Sahm, P R; Spiekermann, H

    2001-06-01

    The objectives of this paper were to simulate the casting process of titanium tooth crowns and bridges; to predict and control porosity defect. A casting simulation software, MAGMASOFT, was used. The geometry of the crowns with fine details of the occlusal surface were digitized by means of laser measuring technique, then converted and read in the simulation software. Both mold filling and solidification were simulated, the shrinkage porosity was predicted by a "feeding criterion", and the gas pore sensitivity was studied based on the mold filling and solidification simulations. Two types of dental prostheses (a single-crown casting and a three-unit-bridge) with various sprue designs were numerically "poured", and only one optimal design for each prosthesis was recommended for real casting trial. With the numerically optimized design, real titanium dental prostheses (five replicas for each) were made on a centrifugal casting machine. All the castings endured radiographic examination, and no porosity was detected in the cast prostheses. It indicates that the numerical simulation is an efficient tool for dental casting design and porosity control. PMID:15348262

  17. Computational modeling of structure of metal matrix composite in centrifugal casting process

    NASA Astrophysics Data System (ADS)

    Zagórski, Roman

    2007-04-01

    The structure of alumina matrix composite reinforced with crystalline particles obtained during centrifugal casting process are studied. Several parameters of cast process like pouring temperature, temperature, rotating speed and size of casting mould which influent on structure of composite are examined. Segregation of crystalline particles depended on other factors such as: the gradient of density of the liquid matrix and reinforcement, thermal processes connected with solidifying of the cast, processes leading to changes in physical and structural properties of liquid composite are also investigated. All simulation are carried out by CFD program Fluent. Numerical simulations are performed using the FLUENT two-phase free surface (air and matrix) unsteady flow model (volume of fluid model — VOF) and discrete phase model (DPM).

  18. Modelling of shrinkage cavity defects during the wheel and belt casting process

    NASA Astrophysics Data System (ADS)

    Dablement, S.; Mortensen, D.; Fjaer, H.; Lee, M.; Grandfield, J.; Savage, G.; Nguyen, V.

    2012-07-01

    Properzi continuous casting is a wheel and belt casting process used for producing aluminium wire rod which is essential to the making of electrical cables and over head lines. One of the main concerns of Properzi process users is to ensure good quality of the final product and to avoid cast defects especially the presence of shrinkage cavity. Numerical models developed with the Alsim software, which allows an automatic calculation of gap dependent heat transfer coefficients at the metal-mould interface due to thermal deformation, are used in order to get a better understanding on the shrinkage cavity formation. Models show the effect of process parameters on the cavity defect development and provide initial guidance for users in order to avoid this kind of casting defect.

  19. Materials processing threshold report: 2. Use of low gravity for cast iron process development

    NASA Technical Reports Server (NTRS)

    Frankhouser, W. L.

    1980-01-01

    Potential applications of a low gravity environment of interest to the commercial producers of cast iron were assessed to determine whether low gravity conditions offer potential opportunities to producers for improving cast iron properties and expanding the use of cast irons. The assessment is limited to the gray and nodular types of iron, however, the findings are applicable to all cast irons. The potential advantages accrued through low gravity experiments with cast irons are described.

  20. A Thermal Simulation Method for Solidification Process of Steel Slab in Continuous Casting

    NASA Astrophysics Data System (ADS)

    Zhong, Honggang; Chen, Xiangru; Han, Qingyou; Han, Ke; Zhai, Qijie

    2016-07-01

    Eighty years after the invention of continuous cast of steels, reproducibility from few mm3 samples in the laboratory to m3 product in plants is still a challenge. We have engineered a thermal simulation method to simulate the continuous casting process. The temperature gradient (G L ) and dendritic growth rate (v) of the slab were reproduced by controlling temperature and cooling intensity at hot and chill end, respectively, in our simulation samples. To verify that our samples can simulate the cast slab in continuous casting process, the heat transfer, solidification structure, and macrosegregation of the simulating sample were compared to those of a much larger continuous casting slab. The morphology of solid/liquid interface, solidified shell thickness, and dendritic growth rate were also investigated by in situ quenching the solidifying sample. Shell thickness (δ) determined by our quenching experiment was related to solidification time (τ) by equation: δ = 4.27 × τ 0.38. The results indicated that our method closely simulated the solidification process of continuous casting.

  1. Simulation of ingot casting processes at Deutsche Edelstahlwerke GmbH®

    NASA Astrophysics Data System (ADS)

    Hartmann, L.; Ernst, C.; Klung, J.-S.

    2012-01-01

    To enhance the quality of tool steels it is necessary to analyse all stages of the production process. During the ingot- or continuous casting processes and the following solidification, material and geometry depending reactions cause defects such as macro segregations or porosities. In former times the trial and error approach, together with the experience and creativity of the steelworks engineers was used to improve the as-cast quality, with a high amount of test procedures and a high demand of research time and costs. Further development in software and algorithms has allowed modern simulation techniques to find their way into industrial steel production and casting-simulations are widely used to achieve an accurate prediction of the ingot quality. To improve the as-cast quality, several ingot casting processes of tool steels were studied at the R&D department of Deutsche Edelstahlwerke GmbH by using the numerical casting simulation software MAGMASOFT®. In this paper some results extracted from the simulation software are shown and compared to experimental investigations.

  2. Electroslag-casting process and properties. [2. 25Cr-1 Mo and modified 9Cr-1Mo

    SciTech Connect

    Sikka, V.K.

    1986-09-01

    The electroslag-casting process is an extension of the electroslag-remelting process. The castings produced by this technique have the advantages of smooth defect-free finish, freedom from conventional casting defects, more reproducible mechanical properties, and properties comparable to those of forged products. This report describes the current status of electroslag-casting facilities in Canada and the United States. It also describes the variety of electroslag castings of 2.25Cr-1Mo, modified 9Cr-1Mo, and type 316 stainless steel made during the last four years and the detailed chemical analysis, microstructural characterization, and mechanical property characterization. The mechanical properties are compared with those of the forged and wrought material. This report provides sufficient information about the electroslag-casting process and the properties of the castings to permit consideration of the process for approval by ASTM and ASME Boiler and Pressure Vessel Code committees. 27 refs., 53 figs., 34 tabs.

  3. Determination of heat transfer coefficients at metal/chill interface in the casting solidification process

    NASA Astrophysics Data System (ADS)

    Zhang, Liqiang; Li, Luoxing

    2013-08-01

    The present work focuses on the determination of interfacial heat transfer coefficients (IHTCs) between the casting and metal chill during casting solidification. The proposed method is established based on the least-squares technique and sequential function specification method and can be applied to calculate heat fluxes and IHTCs for other alloys. The accuracy and stability of the method has been investigated by using a typical profile of heat fluxes simulating the practical conditions of casting solidification. In the test process, the effects of various calculation parameters in the inverse algorithm are also analyzed. Moreover, numerically calculated and experimental results are compared by applying the determined IHTCs into the forward heat conduction model with the same boundary conditions. The results show that the numerically calculated temperatures are in good agreement with those measured experimentally. This confirms that the proposed method is a feasible and effective tool for determination of the casting-mold IHTCs.

  4. Influence of the casting processing route on the corrosion behavior of dental alloys.

    PubMed

    Galo, Rodrigo; Rocha, Luis Augusto; Faria, Adriana Claudia; Silveira, Renata Rodrigues; Ribeiro, Ricardo Faria; de Mattos, Maria da Gloria Chiarello

    2014-12-01

    Casting in the presence of oxygen may result in an improvement of the corrosion performance of most alloys. However, the effect of corrosion on the casting without oxygen for dental materials remains unknown. The aim of this study was to investigate the influence of the casting technique and atmosphere (argon or oxygen) on the corrosion behavior response of six different dental casting alloys. The corrosion behavior was evaluated by electrochemical measurements performed in artificial saliva for the different alloys cast in two different conditions: arc melting in argon and oxygen-gas flame centrifugal casting. A slight decrease in open-circuit potential for most alloys was observed during immersion, meaning that the corrosion tendency of the materials increases due to the contact with the solution. Exceptions were the Co-based alloys prepared by plasma, and the Co-Cr-Mo and Ni-Cr-4Ti alloys processed by oxidized flame, in which an increase in potential was observed. The amount of metallic ions released into the artificial saliva solution during immersion was similar for all specimens. Considering the pitting potential, a parameter of high importance when considering the fluctuating conditions of the oral environment, Co-based alloys show the best performance in comparison with the Ni-based alloys, independent of the processing route. PMID:25491859

  5. Evaluation of Interfacial Interactions Between Ti-6Al-4V and Mold Use Ti-Added Backup Coat in Investment Casting

    NASA Astrophysics Data System (ADS)

    Cheng, Xu; Chai, Lianjing; Wu, Guoqing; Wang, Hong; Nan, Hai

    2016-05-01

    In this article, the chemical inertness of shell using Ti-added mullite backup coat against molten Ti-6Al-4V (Ti64) alloy was investigated. The metal/shell interfacial microstructures and compositions were characterized using an optical microscope, scanning electron microscope, roughness tester, and X-ray diffractometer; the hardened layer thickness was evaluated using a microhardness tester. By adding titanium powder into the mullite backup coat, the alpha case and hardened layer thickness of the Ti64 castings were largely reduced with good surface finishing. Silicon ions, from the backup coat, penetrated into the alloy and coarsened the β lath at the metal/shell interfacial area. The Ti powder in the mullite backup coat oxidized and interacted with silica during mold firing and casting, which reduced the silicon and oxygen concentrations at the metal/shell interfacial area. The oxygen penetration depth is thicker than the alpha case layer thickness, and around 0.26 wt pct, oxygen can obviously coarsen the alpha lath at the metal/shell interfacial area during investment casting.

  6. Process Modeling of Low-Pressure Die Casting of Aluminum Alloy Automotive Wheels

    NASA Astrophysics Data System (ADS)

    Reilly, C.; Duan, J.; Yao, L.; Maijer, D. M.; Cockcroft, S. L.

    2013-09-01

    Although on initial inspection, the aluminum alloy automotive wheel seems to be a relatively simple component to cast based on its shape, further insight reveals that this is not the case. Automotive wheels are in a select group of cast components that have strict specifications for both mechanical and aesthetic characteristics due to their important structural requirements and their visibility on a vehicle. The modern aluminum alloy automotive wheel continues to experience tightened tolerances relating to defects to improve mechanical performance and/or the physical appearance. Automotive aluminum alloy wheels are assessed against three main criteria: wheel cosmetics, mechanical performance, and air tightness. Failure to achieve the required standards in any one of these categories will lead to the wheel either requiring costly repair or being rejected and remelted. Manufacturers are becoming more reliant on computational process modeling as a design tool for the wheel casting process. This article discusses and details examples of the use of computational process modeling as a predictive tool to optimize the casting process from the standpoint of defect minimization with the emphasis on those defects that lead to failure of aluminum automotive wheels, namely, macroporosity, microporosity, and oxide films. The current state of applied computational process modeling and its limitations with regard to wheel casting are discussed.

  7. Technical development of double-clad process for thin strip casting of carbon steel

    SciTech Connect

    Brown, H.L.; Forkel, C.E.; Knudson, D.L.

    1984-08-01

    This report documents the technical development for a patent disclosure of a double-clad process for the continuous casting of thin-strip carbon steel. The fundamental idea of the disclosure is to form a product strip by depositing molten steel between two, cooled, clad strips of the same material. The claimed benefits include: (a) the conservation of energy in steel making through the elimination of soaking pits and reheat cycles, and (b) an improved surface on both sides of the as-cast product such that it will be suitable for direct feed to a cold-reduction mill. However, the process as conceived is not necessarily limited to the casting of carbon steel, but may be also applied to other metals and alloys. The work is described under three headings as follows. Preliminary Considerations and Scoping Analysis presents the basic idea of the double-clad, thin-strip casting process; the energy conservation potential; scoping heat transfer calculations for the casting process; and independent review of this work. Thermal Analysis for Roller Configuration of Double-Clad Process, presents the development, results, and independent review of a finite-element thermal analysis for the casting process as originally conceived (using only chilled rollers in direct contact with the clad material of the product strip). Further Considerations for Belt Configuration of Double-Clad Process deals with a modified equipment design which interposes two product support belts, one on each side of the product, between the clad strip and the rollers. In addition to the process description, this section presents the preliminary mechanical calculations for the endless metal belts and the work scope and results for the computer model revision and thermal analysis for the modified concept.

  8. HANFORD CONTAINERIZED CAST STONE FACILITY TASK 1 PROCESS TESTING & DEVELOPMENT FINAL TEST REPORT

    SciTech Connect

    LOCKREM, L L

    2005-07-13

    Laboratory testing and technical evaluation activities on Containerized Cast Stone (CCS) were conducted under the Scope of Work (SOW) contained in CH2M HILL Hanford Group, Inc. (CHG) Contract No. 18548 (CHG 2003a). This report presents the results of testing and demonstration activities discussed in SOW Section 3.1, Task I--''Process Development Testing'', and described in greater detail in the ''Containerized Grout--Phase I Testing and Demonstration Plan'' (CHG, 2003b). CHG (2003b) divided the CCS testing and evaluation activities into six categories, as follows: (1) A short set of tests with simulant to select a preferred dry reagent formulation (DRF), determine allowable liquid addition levels, and confirm the Part 2 test matrix. (2) Waste form performance testing on cast stone made from the preferred DRF and a backup DRF, as selected in Part I, and using low activity waste (LAW) simulant. (3) Waste form performance testing on cast stone made from the preferred DRF using radioactive LAW. (4) Waste form validation testing on a selected nominal cast stone formulation using the preferred DRF and LAW simulant. (5) Engineering evaluations of explosive/toxic gas evolution, including hydrogen, from the cast stone product. (6) Technetium ''getter'' testing with cast stone made with LAW simulant and with radioactive LAW. In addition, nitrate leaching observations were drawn from nitrate leachability data obtained in the course of the Parts 2 and 3 waste form performance testing. The nitrate leachability index results are presented along with other data from the applicable activity categories.

  9. Solidification Microstructure of AISI M2 High Speed Steel Manufactured by the Horizontal Continuous Casting Process

    NASA Astrophysics Data System (ADS)

    Zhou, X. F.; Fang, F.; Jiang, J. Q.

    2011-01-01

    In the present work, AISI M2 high speed steel is produced by the horizontal continuous casting process. The difference of solidification microstructure in ingots by mould casting and continuous casting has been examined by means of scanning electron microscope (SEM), electron back-scatter diffraction (EBSD), transmission electron microscope (TEM) and high resolution electron microscope (HREM). The results show that the as-cast structure consists of iron matrix and networks of M2C eutectic carbides, which are greatly refined in the continuous casting ingot compared to the case of ingot by mould casting. Meanwhile, the morphology of M2C eutectic carbides changes from the plate-like shape into the fibrous one. Micro-twining and stacking faults are observed in the plate-like M2C, whereas they are rarely identified in the fibrous M2C. Based on the characteristic of morphology and microstructure, it is expected that the plate-like M2C is a faceted phase while the fibrous M2C is a non-faceted phase.

  10. Process for Producing a Cast Article from a Hypereutectic Aluminum-Silicon Alloy

    NASA Technical Reports Server (NTRS)

    Lee, Jonathan A. (Inventor); Chen, Po-Shou (Inventor)

    2003-01-01

    A process for making a cast article from an aluminum alloy includes first casting an article from an alloy having the following composition, in weight percent: Silicon (Si) 14.0-25.0, Copper (CU) 5.5-8.0, Iron (Fe) 0-0.8, Magnesium (Mg) 0.5-1.5, Nickel (Ni) 0.05-1.2, Manganese (Mn) 0-1.0, Titanium (Ti) 0.05-1.2, Zirconium (Zr) 0.12-1.2, Vanadium (V) 0.05-1.2, Zinc (Zn) 0-0.9, Phosphorus (P) 0.001-0.1, Aluminum, balance. In this alloy the ration of Si:Mg is 15-35, and the ratio of Cu:Mg is 4-15. After an article is cast from the alloy, the cast article is aged at a temperature within the range of 400 F to 500 F for a time period within the range of four to 16 hours. It has been found especially advantageous if the cast article is first exposed to a solutionizing step prior to the aging step. This solutionizing step is carried out by exposing the cast article to a temperature within the range of 875 F to 1025 F for a time period of fifteen minutes to four hours. It has also been found to be especially advantageous if the solutionizing step is followed directly with a quenching step, wherein the cast article is quenched in a quenching medium such as water at a temperature within the range of 120 F to 300 F. The resulting cast article is highly suitable in a number of high temperature applications, such as heavy-duty pistons for internal combustion engines.

  11. Development of an Optimization Methodology for the Aluminum Alloy Wheel Casting Process

    NASA Astrophysics Data System (ADS)

    Duan, Jianglan; Reilly, Carl; Maijer, Daan M.; Cockcroft, Steve L.; Phillion, Andre B.

    2015-08-01

    An optimization methodology has been developed for the aluminum alloy wheel casting process. The methodology is focused on improving the timing of cooling processes in a die to achieve improved casting quality. This methodology utilizes (1) a casting process model, which was developed within the commercial finite element package, ABAQUS™—ABAQUS is a trademark of Dassault Systèms; (2) a Python-based results extraction procedure; and (3) a numerical optimization module from the open-source Python library, Scipy. To achieve optimal casting quality, a set of constraints have been defined to ensure directional solidification, and an objective function, based on the solidification cooling rates, has been defined to either maximize, or target a specific, cooling rate. The methodology has been applied to a series of casting and die geometries with different cooling system configurations, including a 2-D axisymmetric wheel and die assembly generated from a full-scale prototype wheel. The results show that, with properly defined constraint and objective functions, solidification conditions can be improved and optimal cooling conditions can be achieved leading to process productivity and product quality improvements.

  12. Instantaneous Formation of Block Copolymer Patterns via Solvo-Thermal Casting Process

    NASA Astrophysics Data System (ADS)

    Jung, Hyun Jung; Woo, Sanghoon; Huh, June; Bang, Joona

    2015-03-01

    A self-assembly of block copolymers (BCPs) exhibits one of the most promising alternative methods for the next-generation lithography. Many semiconductor companies have explored the possibility of implementing this process in actual chip process, whereas the critical challenges such as feature size control, defect density, and long processing time need to be overcome. Regarding the BCP process, the formation of BCP patterns usually requires long processing time via thermal or solvent annealing. Herein we developed a simple processing method to promote a microphase separation of BCPs using solvo-thermal spin casting process. Spin casting has a very similar mechanism to solvent vapor annealing but its short process time prevents BCP chains from reaching equilibrium morphology. To maximize the chain mobility, we employed a high boiling point solvent and also applied the heat during spin casting. As a result, a well ordered BCP patterns were obtained within less than 5 min via solvo-thermal casting process without further additional annealing step.

  13. Evaluation of a Heat Flux Sensor for Spray Cooling for the Die Casting Processes

    SciTech Connect

    Sabau, Adrian S; Wu, Zhuoxi

    2007-02-01

    During the die casting process, lubricants are sprayed in order to cool the dies and facilitate the ejection of the casting. In this paper, a new technique for measuring the heat flux during lubricant application is evaluated. Data from experiments conducted using water spray are first presented. Water spray experiments were conducted for different initial plate temperatures. Measurements were conducted for the application of two different lubricants, of dilution ratios of 1/15 and 1/50 of lubricant in water. The measurement uncertainties were documented. The results show that the surface temperature decreases initially very fast. Numerical simulation results confirmed that the abrupt temperature drop is not an artifact but illustrates the thermal shock experienced by the dies during the initial stages of lubricant application. The lubricant experiments show that the sensor can be successfully used for testing die lubricants with typical dilution ratios encountered in the die casting process.

  14. Development of low-temperature high-strength integral steel castings for offshore construction by casting process engineering

    NASA Astrophysics Data System (ADS)

    Lim, Sang-Sub; Mun, Jae-Chul; Kim, Tae-Won; Kang, Chung-Gil

    2014-12-01

    In casting steels for offshore construction, manufacturing integral casted structures to prevent fatigue cracks in the stress raisers is superior to using welded structures. Here, mold design and casting analysis were conducted for integral casting steel. The laminar flow of molten metal was analyzed and distributions of hot spots and porosities were studied. A prototype was subsequently produced, and air vents were designed to improve the surface defects caused by the release of gas. A radiographic test revealed no internal defects inside the casted steel. Evaluating the chemical and mechanical properties of specimens sampled from the product revealed that target values were quantitatively satisfied. To assess weldability in consideration of repair welding, the product was machined with grooves and welded, after which the mechanical properties of hardness as well as tensile, impact, and bending strengths were evaluated. No substantive differences were found in the mechanical properties before and after welding.

  15. Effect of surfactant on surface hardness of dental stone and investment casts produced from polyvinyl siloxane duplicating materials.

    PubMed

    Al-Johani, Attalah; Clark, Robert K F; Juszczyk, Andrzej S; Radford, David R

    2008-06-01

    Polyvinylsiloxane duplicating materials are typically treated with a topical surfactant before pouring dental models, but the use of topical surfactants in the dental laboratory may affect the surface hardness of the resultant models. The effect of two different topical surfactants on surface hardness of two dental stones (FujiRock and Dentstone) and one phosphate bonded investment material (Croform WB) produced from polyvinyl siloxane (PVS) dental laboratory duplicating moulds was investigated. Topical surfactants affected the surface hardness of FujiRock, Dentstone and Croform WB investment material. Surface hardness of FujiRock increased with Wax-Mate surfactant. However, surface hardness of Croform WB investment material decreased with both topical surfactants. PMID:18637383

  16. Hydroxyapatite scaffolds processed using a TBA-based freeze-gel casting/polymer sponge technique.

    PubMed

    Yang, Tae Young; Lee, Jung Min; Yoon, Seog Young; Park, Hong Chae

    2010-05-01

    A novel freeze-gel casting/polymer sponge technique has been introduced to fabricate porous hydroxyapatite scaffolds with controlled "designer" pore structures and improved compressive strength for bone tissue engineering applications. Tertiary-butyl alcohol (TBA) was used as a solvent in this work. The merits of each production process, freeze casting, gel casting, and polymer sponge route were characterized by the sintered microstructure and mechanical strength. A reticulated structure with large pore size of 180-360 microm, which formed on burn-out of polyurethane foam, consisted of the strut with highly interconnected, unidirectional, long pore channels (approximately 4.5 microm in dia.) by evaporation of frozen TBA produced in freeze casting together with the dense inner walls with a few, isolated fine pores (<2 microm) by gel casting. The sintered porosity and pore size generally behaved in an opposite manner to the solid loading, i.e., a high solid loading gave low porosity and small pore size, and a thickening of the strut cross section, thus leading to higher compressive strengths. PMID:20099009

  17. Polymer-melt interactions during casting formation in the lost foam process

    SciTech Connect

    Shivkumar, S.; Yao, X.; Makhlouf, M.

    1995-07-01

    The lost foam casting process utilizes injection modeled polymeric foam patterns for the production of metallic components. Foamed polymer patterns of the desired shape are coated with a water-based refractory slurry, dried and embedded in unbonded sand. Molten metal is poured directly on the coated polymer. The polymer undergoes thermal degradation and is gradually replaced by the liquid metal to yield the casting after solidification. Expanded polystyrene (EPS) is the most common pattern material used in commercial practice. The use of EPS patterns with ferrous castings may result in the formation of carbonaceous defects in the casting. Consequently, polymethylmethacrylate (PMMA) and copolymers of EPS and PMMA have been developed for ferrous castings. The thermal degradation of the foamed pattern results in the formation of gaseous degradation products and of a partially depolymerized viscous residue. The fraction of viscous residue increased with temperature and is essentially constant above about 650 C. During the filling of EPS patterns, nearly 60% of the polymer is converted to the viscous residue and 40% is transformed to gaseous products. In the case of PMM, almost 60% of the polymer undergoing degradation at the metal front is transformed to gaseous products. The melt flow velocity during the filling of the mold generally increases with temperature.

  18. The effect of process parameters on the internal quality of an aluminum die casting

    NASA Astrophysics Data System (ADS)

    Dewit, M. C. A. J.

    1986-01-01

    The influence of process parameters on the porosity of an aluminum die casting was investigated. Two types of die one of which had an interchangeable gate and two alloys, AlSi8Cu3 and AlSi7, were used. During the solidification phase of a die casting, air entrapment can occur; the air remains in the die casting under high pressure after solidification. The Rayleigh number which contains the velocity in the gate, the gate diameter, and the liquid metal surface tension, determines the air entrapment. It appears that there are two types of filling: solid front filling at low velocities, and standard spray filling at high velocities. With the former type, the castings contain no air, but the shrinkage is concentrated in big holes; with the latter type the castings contain much air, and the shrinkage is distributed over fine holes. The first phase velocity has no significant influence on the porosity; a decrease of the third phase velocity increases the porosity. Variations of the changeover point between the first and second phase have little influence.

  19. Characteristics of Cast Stone cementitious waste form for immobilization of secondary wastes from vitrification process

    NASA Astrophysics Data System (ADS)

    Chung, Chul-Woo; Um, Wooyong; Valenta, Michelle M.; Sundaram, S. K.; Chun, Jaehun; Parker, Kent E.; Kimura, Marcia L.; Westsik, Joseph H.

    2012-01-01

    The high-temperature in vitrification process of radioactive wastes could cause radioactive technetium ( 99Tc) in secondary liquid wastes to become volatile. Solidified cementitious waste forms at low temperature were developed to immobilize radioactive secondary waste. This research focuses on the characterization of a cementitious waste form called Cast Stone. Properties including compressive strength, surface area, phase composition, and technetium leaching were measured. The results indicate that technetium diffusivity is affected by simulant type. Additionally, ettringite and AFm (Al 2O 3-Fe 2O 3-mono) main crystalline phases were formed during hydration. The Cast Stone waste form passed the qualification requirements for a secondary waste form, which are compressive strength of 3.45 MPa and technetium diffusivity of 10 -9 cm 2/s. Cast Stone was found to be a good candidate for immobilizing secondary waste streams.

  20. A high resolution finite volume method for efficient parallel simulation of casting processes on unstructured meshes

    SciTech Connect

    Kothe, D.B.; Turner, J.A.; Mosso, S.J.; Ferrell, R.C.

    1997-03-01

    We discuss selected aspects of a new parallel three-dimensional (3-D) computational tool for the unstructured mesh simulation of Los Alamos National Laboratory (LANL) casting processes. This tool, known as {bold Telluride}, draws upon on robust, high resolution finite volume solutions of metal alloy mass, momentum, and enthalpy conservation equations to model the filling, cooling, and solidification of LANL castings. We briefly describe the current {bold Telluride} physical models and solution methods, then detail our parallelization strategy as implemented with Fortran 90 (F90). This strategy has yielded straightforward and efficient parallelization on distributed and shared memory architectures, aided in large part by new parallel libraries {bold JTpack9O} for Krylov-subspace iterative solution methods and {bold PGSLib} for efficient gather/scatter operations. We illustrate our methodology and current capabilities with source code examples and parallel efficiency results for a LANL casting simulation.

  1. Workplace Basic Skills in the Metal Casting Industry for World Class Process and Technology.

    ERIC Educational Resources Information Center

    Rasmussen, Bonnie

    A workplace basic skills project for the metal casting industry was established jointly by Central Alabama Community College and Robinson Foundry, Inc. Evaluation of the project was made through a commercial test of hourly workers' general literacy level gains, instructor-developed pre- and posttests of mastery of the industrial process and…

  2. Part I: In-situ fluorometric quantification of microalgal neutral lipids. Part II: Thermal degradation behavior of investment casting polymer patterns

    NASA Astrophysics Data System (ADS)

    Zhao, Hongfang

    Research described in this dissertation covers two topics. Part-I is focused on in-situ determination of neutral lipid content of microalgae using a lipophilic fluorescent dye. The traditional Nile red stain-based method for detecting microalgal intracellular lipids is limited due to varying composition and thickness of rigid cell walls. In this study, the addition of dilute acid and heating of solution, were found to greatly enhance staining efficiency of Nile red for microalgal species evaluated. Oil-in-water (O/W) microemulsion stabilized by a non-ionic surfactant was employed as a pseudo-standard that mimics lipid-bearing microalgal cells suspended in water. The average neutral lipid contents determined were very close to the results obtained by traditional gravimetric method and solid phase extraction. Part II of the dissertation explores thermo-physico-chemical properties of polymeric pattern materials, including expanded polystyrene (EPS) foam, polyurethane foam, and epoxy stereolithography (SLA) patterns, that are used in investment casting. Density, elastic modulus, expansion coefficient, thermal degradation behavior, etc. were experimentally investigated for their effects on metal casting quality. The reduction in toxic hydrogen cyanide (HCN) generated during thermal decomposition of polyurethane pattern was achieved by increasing either oxidant level or residence time in heated zone. Thermal degradation kinetics of the pattern materials were examined with a thermogravimetric analysis and activation energies were determined by Kissinger and Flynn-Wall-Ozawa methods.

  3. The Influence of Casting Conditions on the Microstructure of As-Cast U-10Mo Alloys: Characterization of the Casting Process Baseline

    SciTech Connect

    Nyberg, Eric A.; Joshi, Vineet V.; Lavender, Curt A.; Paxton, Dean M.; Burkes, Douglas

    2013-12-13

    Sections of eight plate castings of uranium alloyed with 10 wt% molybdenum (U-10Mo) were sent from Y-12 to the Pacific Northwest National Laboratory (PNNL) for microstructural characterization. This report summarizes the results from this study.

  4. Heat-Transfer Measurements in the Primary Cooling Phase of the Direct-Chill Casting Process

    NASA Astrophysics Data System (ADS)

    Caron, Etienne J. F. R.; Baserinia, Amir R.; Ng, Harry; Wells, Mary A.; Weckman, David C.

    2012-10-01

    Thermal modeling of the direct-chill casting process requires accurate knowledge of (1) the different boundary conditions in the primary mold and secondary direct water-spray cooling regimes and (2) their variability with respect to process parameters. In this study, heat transfer in the primary cooling zone was investigated by using temperature measurements made with subsurface thermocouples in the mold as input to an inverse heat conduction algorithm. Laboratory-scale experiments were performed to investigate the primary cooling of AA3003 and AA4045 aluminum alloy ingots cast at speeds ranging between 1.58 and 2.10 mm/s. The average heat flux values were calculated for the steady-state phase of the casting process, and an effective heat-transfer coefficient for the global primary cooling process was derived that included convection at the mold surfaces and conduction through the mold wall. Effective heat-transfer coefficients were evaluated at different points along the mold height and compared with values from a previously derived computational fluid dynamics model of the direct-chill casting process that were based on predictions of the air gap thickness between the mold and ingot. The current experimental results closely matched the values previously predicted by the air gap models. The effective heat-transfer coefficient for primary cooling was also found to increase slightly with the casting speed and was higher near the mold top (up to 824 W/m2·K) where the molten aluminum first comes in contact with the mold than near the bottom (as low as 242 W/m2·K) where an air gap forms between the ingot and mold because of thermal contraction of the ingot. These results are consistent with previous studies.

  5. Biostratinomic processes for the development of mud-cast logs in Carboniferous and Holocene swamps

    SciTech Connect

    Gastaldo, R.A.; Demko, T.M.; Liu, Yuejin; Keefer, W.D.; Abston, S.L. )

    1989-08-01

    Prostrate trees are common features of fossil forest litters, and are frequently preserved as mud-casts. Specimens of Carboniferous mud-cast trees and a mud-filled incipient cast of a Holocene Taxodium have been investigated to determine the biostratinomic processes responsible for their formation. These processes are complex. Hollowing of tree trunks may take place during life or by degradation after death. Once the trunk has fallen, the hollow cavity is supported by surrounding wood and/or bark tissues and acts as a conduit for sediment-laden waters. Leaf litter may be preserved on bedding surfaces. The infilling sequence of horizontal, parallel bedded, fine-grained sediment is deposited from suspended load during multiple overbank flooding events. These results differ from experimentally produced pith casts in which the sediment grain size is of fine sand. In Holocene specimens, alluvial mud within the log may provide a substrate for infaunal invertebrates. No evidence of infaunal burrowing in Carboniferous analogues exists.

  6. Numerical simulation of solid liquid interface behavior during continuous strip casting process.

    PubMed

    Lee, Changbum; Yoon, Wooyoung; Shin, Seungwon; Lee, Jaewoo; Jang, Bo-Yun; Kim, Joonsoo; Ahn, Youngsoo; Lee, Jinseok

    2013-05-01

    A new metal-strip-casting process called continuous strip-casting (CSC) has been developed for making thin metal strips. A numerical simulation model to help understand solid-liquid interface behavior during CSC has been developed and used to identify the solidification morphologies of the strips and to determine the optimum processing conditions. In this study, we used a modified level contour reconstruction method (LCRM) and the sharp interface method to modify interface tracking, and performed a simulation analysis of the CSC process. The effects of process parameters such as heat-transfer coefficient and extrusion velocity on the behavior of the solid-liquid interface were estimated and used to improve the apparatus. A Sn (Tin) plate of dimensions 200 x 50 x 1 mm3 was successfully produced by CSC for a heat-transfer coefficient of 104 W/m2 K and an extrusion velocity of 0.2 m/s. PMID:23858856

  7. Process automation for high-speed-thin-gauge-twin roll casting technology

    SciTech Connect

    Maiwald, K.P.; Mariethoz, B.

    1996-10-01

    The successful joint venture development between Lauener-Engineering and Hydro-Aluminum in respect to thin gauge-high-speed-casting demanded a highly sophisticated process-control system. The targets of 100% (and above) productivity increases and gauges of 2 mm and below within tolerances of {+-} 1% and below where reached on time. The paper will explore details of the process control system applied from furnace to caster and coiler.

  8. Advances in aluminum casting technology

    SciTech Connect

    Tiryakioglu, M.; Campbell, J.

    1998-01-01

    This symposium focuses on the improvements of aluminum casting quality and reliability through a better understanding of processes and process variables, and explores the latest innovations in casting-process design that allow increasing use of the castings to replace complex assemblies and heavy steel and cast-iron components in aerospace and automotive applications. Presented are 35 papers by international experts in the various aspects of the subject. The contents include: Semisolid casting; Computer-aided designing of molds and castings; Casting-process modeling; Aluminum-matrix composite castings; HIPing of castings; Progress in the US car project; Die casting and die design; and Solidification and properties.

  9. Process development for producing fine-grain casting in space

    NASA Technical Reports Server (NTRS)

    Gelles, S. H.; Malik, R. K.

    1975-01-01

    Assessment of grain growth kinetics at temperatures near the melting point and investigation into the use of potential nucleating agents in combination with the naturally occurring BeO led to the definition of critical low-g experiments which would help to determine whether one or both of these possibilities are valid and whether space processing would be able to yield fine grain ingot beryllium.

  10. The potential of centrifugal casting for the production of near net shape uranium parts

    SciTech Connect

    Robertson, E.

    1993-09-01

    This report was written to provide a detailed summary of a literature survey on the near net shape casting process of centrifugal casting. Centrifugal casting is one potential casting method which could satisfy the requirements of the LANL program titled Near Net Shape Casting of Uranium for Reduced Environmental, Safety and Health Impact. In this report, centrifugal casting techniques are reviewed and an assessment of the ability to achieve the near net shape and waste minimization goals of the LANL program by using these techniques is made. Based upon the literature reviewed, it is concluded that if properly modified for operation within a vacuum, vertical or horizontal centrifugation could be used to safely cast uranium for the production of hollow, cylindrical parts. However, for the production of components of geometries other than hollow tubes, vertical centrifugation could be combined with other casting methods such as semi-permanent mold or investment casting.

  11. Shape Memory Effect in Cast Versus Deformation-Processed NiTiNb Alloys

    NASA Astrophysics Data System (ADS)

    Hamilton, Reginald F.; Lanba, Asheesh; Ozbulut, Osman E.; Tittmann, Bernhard R.

    2015-06-01

    The shape memory effect (SME) response of a deformation-processed NiTiNb shape memory alloy is benchmarked against the response of a cast alloy. The insoluble Nb element ternary addition is known to widen the hysteresis with respect to the binary NiTi alloy. Cast microstructures naturally consist of a cellular arrangement of characteristic eutectic microconstituents surrounding primary matrix regions. Deformation processing typically aligns the microconstituents such that the microstructure resembles discontinuous fiber-reinforced composites. Processed alloys are typically characterized for heat-to-recover applications and thus deformed at constant temperature and subsequently heated for SME recovery, and the critical stress levels are expected to facilitate plastic deformation of the microconstituents. The current work employs thermal cycling under constant bias stresses below those critical levels. This comparative study of cast versus deformation-processed NiTiNb alloys contrasts the strain-temperature responses in terms of forward Δ T F = M s - M f and reverse Δ T R = A f - A s temperature intervals, the thermal hysteresis, and the recovery ratio. The results underscore that the deformation-processed microstructure inherently promotes irreversibility and differential forward and reverse transformation pathways.

  12. Interaction analysis of the twin-roller strip-casting process and the implications for process control

    NASA Astrophysics Data System (ADS)

    Edwards, John B.; Cavazos, Alberto

    2005-06-01

    Twin-roller steel strip casting may offer advantages with respect to classic continuous-casting hot-rolling processes. Only a few studies have reported control aspects of this process, and, although successful, little attention has been given to the interactions between variables. In this study, the derivation of a 3 × 3 linearized multivariable model for process control purposes that has been proposed in previous investigations is presented. The model was simplified to a 2×2 plant. The process was found to be highly interactive and nonlinear, involving time delays. An analysis of interactions and their implications for process control is also presented. The multivariable model proposed was successfully used for multivariable control design in subsequent works.

  13. Numerical Simulation of Cast Distortion in Gas Turbine Engine Components

    NASA Astrophysics Data System (ADS)

    Inozemtsev, A. A.; Dubrovskaya, A. S.; Dongauser, K. A.; Trufanov, N. A.

    2015-06-01

    In this paper the process of multiple airfoilvanes manufacturing through investment casting is considered. The mathematical model of the full contact problem is built to determine stress strain state in a cast during the process of solidification. Studies are carried out in viscoelastoplastic statement. Numerical simulation of the explored process is implemented with ProCASTsoftware package. The results of simulation are compared with the real production process. By means of computer analysis the optimization of technical process parameters is done in order to eliminate the defect of cast walls thickness variation.

  14. Numerical Simulation of Filling Process During Twin-Roll Strip Casting

    NASA Astrophysics Data System (ADS)

    Liu, Zhiyu; Wang, Bo; Zhang, Qinghua; Ma, Jie; Zhang, Jieyu

    2014-01-01

    The modeling and controlling of flow and solidification of melt metal in the filling process is important for obtaining the optimal pool level and the formation of the solidified metal layer on the surface of twin-rolls during the twin-roll strip casting. The proper delivery system and processing parameters plays a key role to control flow characteristics in the initial filling stage of the twin-roll strip casting process. In this paper, a commercial CFD software was employed to simulate the transient fluid flow, heat transfer, and solidifications behaviors during the pouring stage of twin-roll strip casting process using different delivery systems. A 3D model was set up to solve the coupled set of governing differential equations for mass, momentum, and energy balance. The transient free-surface problem was treated with the volume of fluid approach, a k-ɛ turbulence model was employed to handle the turbulence effect and an enthalpy method was used to predict phase change during solidification. The predicted results showed that a wedge-shaped delivery system might have a beneficial impact on the distribution of molten steel and solidification. The predicted surface profile agreed well with the measured values in water model.

  15. Determination of the heat transfer coefficient at the metal-sand mold interface of lost foam casting process

    NASA Astrophysics Data System (ADS)

    Zhang, Liqiang; Tan, Wenfang; Hu, Hao

    2016-06-01

    For modeling solidification process of casting accurately, a reliable heat transfer boundary condition data is required. In this paper, an inverse conduction model was established to determine the heat flux and heat transfer coefficient at the metal-sand mold interface for cylindrical casting in the lost foam process. The numerically calculated temperature was compared with analytic solution and simulation solution obtained by commercial software ProCAST to investigate the accuracy of heat conduction model. The instantaneous cast and sand mold temperatures were measured experimentally and these values were used to determine the interfacial heat transfer coefficient (IHTC). The IHTC values during lost foam casting were shown to vary from 20 to 800 W m-2 K-1. Additionally, the characteristics of the time-varying IHTC have also been discussed in this study.

  16. Urinary casts

    MedlinePlus

    ... people with advanced kidney disease and chronic kidney failure . White blood cell (WBC) casts are more common ... Hyaline casts; Granular casts; Renal tubular epithelial casts; Waxy casts; Casts in the ...

  17. Urinary casts

    MedlinePlus

    ... Casts in the urine; Fatty casts; Red blood cell casts; White blood cell casts ... The absence of cellular casts or presence of a few hyaline casts is normal. The examples above are common measurements for results of ...

  18. Processing of Advanced Cast Alloys for A-USC Steam Turbine Applications

    NASA Astrophysics Data System (ADS)

    Jablonski, Paul D.; Hawk, Jeffery A.; Cowen, Christopher J.; Maziasz, Philip J.

    2012-02-01

    The high-temperature components within conventional supercritical coal-fired power plants are manufactured from ferritic/martensitic steels. To reduce greenhouse-gas emissions, the efficiency of pulverized coal steam power plants must be increased to as high a temperature and pressure as feasible. The proposed steam temperature in the DOE/NETL Advanced Ultra Supercritical power plant is high enough (760°C) that ferritic/martensitic steels will not work for the majority of high-temperature components in the turbine or for pipes and tubes in the boiler due to temperature limitations of this class of materials. Thus, Ni-based superalloys are being considered for many of these components. Off-the-shelf forged nickel alloys have shown good promise at these temperatures, but further improvements can be made through experimentation within the nominal chemistry range as well as through thermomechanical processing and subsequent heat treatment. However, cast nickel-based superalloys, which possess high strength, creep resistance, and weldability, are typically not available, particularly those with good ductility and toughness that are weldable in thick sections. To address those issues related to thick casting for turbine casings, for example, cast analogs of selected wrought nickel-based superalloys such as alloy 263, Haynes 282, and Nimonic 105 have been produced. Alloy design criteria, melt processing experiences, and heat treatment are discussed with respect to the as-processed and heat-treated microstructures and selected mechanical properties. The discussion concludes with the prospects for full-scale development of a thick section casting for a steam turbine valve chest or rotor casing.

  19. Development of an Innovative Laser-Assisted Coating Process for Extending Lifetime of Metal Casting Dies. Final Report

    SciTech Connect

    Madhav Rao Gonvindaraju

    1999-10-18

    Die casting dies used in the metal casting industry fail due to thermal fatigue cracking accompanied by the presence of residual tensile stresses, corrosion, erosion and wear of die surfaces. This phase 1 SBIR Final Report summarize Karta Technologies research involving the development of an innovative laser coating technology for metal casting dies. The process involves depositing complex protective coatings of nanocrystalline powders of TiC followed by a laser shot peening. The results indicate a significant improvement in corrosion and erosion resistance in molten aluminum for H13 die casting die steels. The laser-coated samples also showed improved surface finish, a homogeneous and uniform coating mircrostructure. The technology developed in this research can have a significant impact on the casting industry by saving the material costs involved in replacing dies, reducing downtime and improving the quality.

  20. Fatigue behaviour of friction stir processed AZ91 magnesium alloy produced by high pressure die casting

    SciTech Connect

    Cavaliere, P. . E-mail: pasquale.cavaliere@unile.it; De Marco, P.P.

    2007-03-15

    The room temperature fatigue properties of AZ91 magnesium alloy produced by high pressure die casting (HPDC) as cast, heat treated, friction stir processed (FSP) and FSP and heat treated were studied. The fatigue properties of the material were evaluated for the HPDC magnesium alloy in the as-received state and after a solution treatment at 415 deg. C for 2 h and an ageing treatment at 220 deg. C for 4 h. The heat treatment resulted in a significant increase in the fatigue properties of the HPDC material, while no significance influence of heat treatment was recorded in the FSP condition. The morphology of fracture surfaces was examined by employing a field emission gun scanning electron microscope (FEGSEM)

  1. Transient thermal model of the continuous single-wheel thin-strip casting process

    NASA Astrophysics Data System (ADS)

    Li, Guowei; Thomas, Brian G.

    1996-06-01

    A transient heat-transfer model (STRIP1D) has been developed to simulate the single-roll continuous strip-casting process. The model predicts temperature in the solidifying strip coupled with heat transfer in the rotating wheel, using an explicit finite difference procedure. The model has been calibrated using strip thickness data from a test caster at ARMCO Inc. (Middletown, OH) and verified with a range of other available measurements. The strip/wheel interface contact resistance and heat transfer were investigated in particular, and an empirical formula to calculate this heat-transfer coefficient as a function of contact time was obtained. Wheel temperature and final strip thickness are investigated as a function of casting speed, liquid steel pool depth, superheat, coatings on the wheel hot surface, strip detachment point, wheel wall thickness, and wheel material.

  2. Thermo-Mechanical Behavior of the Continuous Casting Bloom in the Heavy Reduction Process

    NASA Astrophysics Data System (ADS)

    Ji, Cheng; Wu, Chen-hui; Zhu, Miao-yong

    2016-08-01

    A two-stage sequential heavy reduction (HR) method, in which the reduction amount was increased both before and after the solidification end, is presented to simultaneously improve the homogeneity and compactness of the continuous casting bloom. With bearing steel GCr15 chosen as the specific research steel, a three-dimensional thermal-mechanical finite element model was developed to simulate and analyze the thermal and mechanical behaviors of the continuous casting bloom during the HR process. In order to ensure the accuracy of the simulation, the constitutive model parameters were derived from the experimental results. The predicted temperature distribution and shell thickness were verified using a thermal infrared camera and nail shooting results, respectively. The real measured relationship between the HR pressure and amount were applied to verify the mechanical model. The explorative application results showed that the quality of the bloom center and compactness of rolled bars have both been significantly improved after the HR was applied.

  3. Microstructural modification of as-cast NiAl bronze by friction stir processing

    NASA Astrophysics Data System (ADS)

    Oh-Ishi, Keiichiro; McNelley, Terry R.

    2004-09-01

    The application of friction stir processing (FSP) to a cast NiAl bronze (NAB) material is presented as a means for selective modification of the near-surface layers by converting as-cast microstructures to a wrought condition in the absence of macroscopic shape change. This may enable selective surface hardening of cast components. The complex physical metallurgy of the NAB is reviewed, and microstructure changes associated with FSP for a selected set of processing parameters are examined by optical microscopy (OM) and transmission electron microscopy (TEM) methods. Direct temperature measurement in the stir zone is infeasible and, so, these microstructure changes are used to estimate peak temperatures in the stir zone. The persistence of a Fe3Al phase ( κ ii) indicates that peak temperatures are below the solvus for this phase, while the presence of transformation products of the β phase, including fine Widmanstätten α, bainite, and martensite, indicates that peak temperatures exceed the eutectoid temperature for the reaction β → α+ κ iii throughout the stir zone.

  4. Freeze casting of porous hydroxyapatite scaffolds. I. Processing and general microstructure.

    PubMed

    Fu, Qiang; Rahaman, Mohamed N; Dogan, Fatih; Bal, B Sonny

    2008-07-01

    Freeze casting of aqueous suspensions on a cold substrate was investigated as a method for preparing hydroxyapatite (HA) scaffolds with unidirectional porosity. In the present paper, we report on the ability to manipulate the microstructure of freeze-cast constructs by controlling the processing parameters. Constructs prepared from aqueous suspensions (5-20 volume percent particles) on a steel substrate at -20 degrees C had a lamellar-type microstructure, consisting of plate-like HA and unidirectional pores oriented in the direction of freezing. Sintering for 3 h at 1350 degrees C produced constructs with dense HA lamellas, porosity of approximately 50%, and inter-lamellar pore widths of 5-30 microm. The thickness of the HA lamellas decreased but the width of the pores increased with decreasing particle concentration. Decreasing the substrate temperature from -20 degrees C to -196 degrees C produced a finer lamellar microstructure. The use of water-glycerol mixtures (20 wt % glycerol) as the solvent in the suspension resulted in the production of finer pores (1-10 microm) and a larger number of dendritic growth connecting the HA lamellas. On the other hand, the use of water-dioxane mixtures (60 wt % dioxane) produced a cellular-type microstructure with larger pores (90-110 microm). The ability to produce a uniaxial microstructure and its manipulation by controlling the processing parameters indicate the potential of the present freeze casting route for the production of scaffolds for bone tissue engineering applications. PMID:18098195

  5. A process model for the microstructure evolution in ductile cast iron. Part 1: The model

    SciTech Connect

    Onsoeien, M.I.; Gundersen, O.; Grong, O.; Skaland, T.

    1999-04-01

    In the present investigation, the multiple phase changes occurring during solidification and subsequent cooling of near-eutectic ductile cast iron have been modeled using the internal state variable approach. According to this formalism, the microstructure evolution is captured mathematically in terms of differential variation of the primary state variables with time for each of the relevant mechanisms. Separate response equations have then been developed to convert the current values of the state variables into equivalent volume fractions of constituent phases utilizing the constraints provided by the phase diagram. The results may conveniently be represented in the form of C curves and process diagrams to illuminate how changes in alloy composition, graphite nucleation potential, and thermal program affect the microstructure evolution at various stages of the process. The model can readily be implemented in a dedicated numerical code for the thermal field in real castings and used as a guiding tool in design of new treatment alloys for ductile cast irons. An illustration of this is given in an accompanying article (Part 2).

  6. Bond Strength of Multicomponent White Cast Iron Coatings Applied by HVOF Thermal Spray Process

    NASA Astrophysics Data System (ADS)

    Maranho, Ossimar; Rodrigues, Daniel; Boccalini, Mario; Sinatora, Amilton

    2009-12-01

    Multicomponent white cast iron is a new alloy that belongs to system Fe-C-Cr-W-Mo-V, and because of its excellent wear resistance it is used in the manufacture of hot rolling mills rolls. To date, this alloy has been processed by casting, powder metallurgy, and spray forming. The high-velocity oxyfuel process is now also considered for the manufacture of components with this alloy. The effects of substrate, preheating temperature, and coating thickness on bond strength of coatings have been determined. Substrates of AISI 1020 steel and of cast iron with preheating of 150 °C and at room temperature were used to apply coatings with 200 and 400 μm nominal thickness. The bond strength of coatings was measured with the pull-off test method and the failure mode by scanning electron microscopic analysis. Coatings with thickness of 200 μm and applied on substrates of AISI 1020 steel with preheating presented bond strength of 87 ± 4 MPa.

  7. The Computational Fluid Dynamic (CFD) Modeling of the Horizontal Single Belt Casting (HSBC) Processing of Al-Mg-Sc-Zr Alloy Strips

    NASA Astrophysics Data System (ADS)

    Ge, S.; Isac, M.; Guthrie, R. I. L.

    2015-10-01

    Al-Mg-Sc-Zr alloys have shown exceptional potential as structural materials for transportation applications. These alloys have proved to be good candidates to be processed as thin strips via the horizontal single belt casting (HSBC) process. The HSBC process is a near-net-shape casting technology, which involves casting molten metal directly into thin strips, close to the final product thickness, at higher cooling rates than conventional continuous casting and thin-slab casting processes. It offers an efficient, economical, and environmentally friendly approach to the production of metal strips. Fluid mechanics and associated heat transfer are important aspects of any casting process, and the novel HSBC process is no exception. Three-dimensional computational fluid dynamics simulations using ANSYS FLUENT 14.5 were performed, in order to assess the importance and effects of the various operational conditions of the HSBC process. This enabled process parameter optimization. Numerical predictions were validated against experimental casting results.

  8. High Wear Resistance of White Cast Iron Treated by Novel Process: Principle and Mechanism

    NASA Astrophysics Data System (ADS)

    Jia, Xiaoshuai; Zuo, Xunwei; Liu, Yu; Chen, Nailu; Rong, Yonghua

    2015-12-01

    Based on microstructure desired, a novel process is proposed to treat Fe-2.4C-12.0Cr (mass pct) white cast iron balls, that is, destabilizing heat treatment following multicycle quenching and sub-critical treatment (De-MQ-Sct) process, and such a complex process is simply performed by alternate water quenching and air cooling. For comparison, the white cast iron balls also were treated by conventional normalization (NOR) process and Oil-quenching process, respectively. The partitioning of carbon from martensite to retained austenite during De-MQ-Sct process promotes the interaction between carbide precipitation and martensitic transformation, while this interaction is a unique effect only produced by multicycle quenching linking destabilizing and sub-critical treatments, which leads to more and finer secondary carbides and more carbon-enriched austenite in De-MQ-Sct sample than those in NOR or Oil-quenching sample. The average hardness of 60 HRC and impact toughness of 12.6 J/cm2 are obtained in De-MQ-Sct white cast iron balls, which are much higher than those in NOR and Oil-quenching ones. The wear behaviours measured by pin-on-disk wear tests indicate that the weight loss of De-MQ-Sct sample is only about one third of the NOR sample and one half of the Oil-quenching sample. Microstructural characterization reveals that high wear resistance related to hardness and toughness of the De-MQ-Sct balls are mainly attributed to the considerable fine secondary carbides and stable carbon-enriched retained austenite.

  9. AMCC casting development. Volume 1: Executive Summary

    NASA Astrophysics Data System (ADS)

    1995-03-01

    The Advanced Combustion Chamber Casting (AMCC) has been a technically challenging part due to its size, configuration, and alloy type. The height and weight of the wax pattern assembly necessitated the development of a hollow gating system to ensure structural integrity of the shell throughout the investment process. The complexity in the jacket area of the casting required the development of an innovative casting technology that PCC has termed 'TGC' or Thermal Gradient Control. This method, of setting up thermal gradients in the casting during solidification, represents a significant process improvement for PCC and has been successfully implemented on other programs. Metallurgical integrity of the final four castings was very good. Only the areas of the parts that utilized 'TGC Shape & Location System #2' showed any significant areas of microshrinkage when evaluated by non-destructive tests. Alumina oxides detected by FPI on the 'float' surfaces (top sid surfaces of the casting during solidification) of the part were almost entirely less than the acceptance criteria of .032 inches in diameter. Destructive chem mill of the castings was required to determine the effect of the process variables used during the processing of these last four parts (with the exception of the 'Shape & Location of TGC' variable).

  10. AMCC casting development. Volume 1: Executive Summary

    NASA Technical Reports Server (NTRS)

    1995-01-01

    The Advanced Combustion Chamber Casting (AMCC) has been a technically challenging part due to its size, configuration, and alloy type. The height and weight of the wax pattern assembly necessitated the development of a hollow gating system to ensure structural integrity of the shell throughout the investment process. The complexity in the jacket area of the casting required the development of an innovative casting technology that PCC has termed 'TGC' or Thermal Gradient Control. This method, of setting up thermal gradients in the casting during solidification, represents a significant process improvement for PCC and has been successfully implemented on other programs. Metallurgical integrity of the final four castings was very good. Only the areas of the parts that utilized 'TGC Shape & Location System #2' showed any significant areas of microshrinkage when evaluated by non-destructive tests. Alumina oxides detected by FPI on the 'float' surfaces (top sid surfaces of the casting during solidification) of the part were almost entirely less than the acceptance criteria of .032 inches in diameter. Destructive chem mill of the castings was required to determine the effect of the process variables used during the processing of these last four parts (with the exception of the 'Shape & Location of TGC' variable).

  11. PREFACE: MCWASP XIII: International Conference on Modeling of Casting, Welding and Advanced Solidification Processes

    NASA Astrophysics Data System (ADS)

    Ludwig, Andreas

    2012-07-01

    Due to fast-paced development in computer technologies during the last three decades, computer-based process modeling has become an important tool for the improvement of existing process technologies and the development of new, innovative technologies. With the help of numerical process simulations, complex and costly experimental trials can now be reduced to a minimum. For metallurgical processes in particular, computer simulations are of outstanding importance, as the flow and solidification of molten alloys or the formation of microstructure and defects can hardly be observed experimentally. Corresponding computer simulations allow us inside views into the key process phenomena and so offer great potential for optimization. In 1980 the conference series 'Modeling of Casting, Welding and Advanced Solidification Processes (MCWASP)' was started up, and has now been continued by holding the 13th international conference on 'Modeling of Casting, Welding and Advanced Solidification Processes', MCWASP XIII, in Schladming, Austria, from June 17-22 2012. Around 200 scientists from industry and academia, coming from 20 countries around the globe attended 78 oral and 50 poster presentations on different aspects of solidification-related modeling topics. Besides process-related sessions such as (i) Ingot and Shape Casting, (ii) Continuous Casting and Direct Chill Casting, (iii) Directional Solidification and Zone Melting, (iv) Welding, and (v) Centrifugal Casting, a larger focus was put on (vi) Experimental Investigation and In-Situ Observations. In recent years, this topic has been significantly strengthened as advanced synchrotron technologies allow fantastic in-situ observations of phenomena happening inside small metallic samples. These observations will definitely serve as a benchmark for the modeling community. Further macroscopic aspects of advanced solidification science were tackled in the sessions (vii) Electromagnetic Coupling, (viii) Thermomechanics, (ix

  12. Structure and properties of polypropylene cast films: Polymer type and processing effects

    NASA Astrophysics Data System (ADS)

    Mileva, Daniela; Gahleitner, Markus; Gloger, Dietrich

    2016-05-01

    The influence of processing parameters in a cast film extrusion process of thin films of isotactic polypropylene homopolymer and random propylene-ethylene copolymer was analyzed. Variation of the chill roll temperature allowed changing the supercooling of the melt and thus the generation of different crystal polymorphs of iPP. Additional focus was placed on the effect of flow induced crystallization via changing the output rate of the line. The crystal structure and morphology of the materials were evaluated and correlated to selected optical and mechanical properties.

  13. Phased Arrays Techniques and Split Spectrum Processing for Inspection of Thick Titanium Casting Components

    NASA Astrophysics Data System (ADS)

    Banchet, J.; Sicard, R.; Zellouf, D. E.; Chahbaz, A.

    2003-03-01

    In aircraft structures, titanium parts and engine members are critical structural components, and their inspection crucial. However, these structures are very difficult to inspect ultrasonically because of their large grain structure that increases noise drastically. In this work, phased array inspection setups were developed to detected small defects such as simulated inclusions and porosity contained in thick titanium casting blocks, which are frequently used in the aerospace industry. A Cut Spectrum Processing (CSP)-based algorithm was then implemented on the acquired data by employing a set of parallel bandpass filters with different center frequencies. This process led in substantial improvement of the signal to noise ratio and thus, of detectability.

  14. Modeling of microstructure evolution of magnesium alloy during the high pressure die casting process

    NASA Astrophysics Data System (ADS)

    Wu, Mengwu; Xiong, Shoumei

    2012-07-01

    Two important microstructure characteristics of high pressure die cast magnesium alloy are the externally solidified crystals (ESCs) and the fully divorced eutectic which form at the filling stage of the shot sleeve and at the last stage of solidification in the die cavity, respectively. Both of them have a significant influence on the mechanical properties and performance of magnesium alloy die castings. In the present paper, a numerical model based on the cellular automaton (CA) method was developed to simulate the microstructure evolution of magnesium alloy during cold-chamber high pressure die casting (HPDC) process. Modeling of dendritic growth of magnesium alloy with six-fold symmetry was achieved by defining a special neighbourhood configuration and calculating of the growth kinetics from complete solution of the transport equations. Special attention was paid to establish a nucleation model considering both of the nucleation of externally solidified crystals in the shot sleeve and the massive nucleation in the die cavity. Meanwhile, simulation of the formation of fully divorced eutectic was also taken into account in the present CA model. Validation was performed and the capability of the present model was addressed by comparing the simulated results with those obtained by experiments.

  15. Study on Fabrication of AA4032/AA6069 Cladding Billet Using Direct Chill Casting Process

    NASA Astrophysics Data System (ADS)

    Han, Xing; Zhang, Haitao; Shao, Bo; Li, Lei; Liu, Xuan; Cui, Jianzhong

    2016-04-01

    AA4032/AA6069 cladding billet in size of φ130 mm/φ110 mm was prepared by the modified direct chill casting process, and the parametric effect on casting performance was investigated using numerical simulation. Microstructures, elements distribution, and mechanical properties of the bonding interface were examined. The results show that metallurgical bonding interface can be obtained with the optimal parameters: the casting speed of 130 to 140 mm/min, the internal liquid level height of 50 to 60 mm, and the contact height of 40 to 50 mm. The metallurgical bonding interface is free of any discontinuities due to the fact that the alloying elements diffused across the interface and formed Ni-containing phase. Tensile strength of the cladding billet reaches 225.3 MPa, and the fracture position was located in AA6069 side, suggesting that the interface bonding strength is higher than the strength of AA6069. The interfacial shearing strength is 159.3 MPa, indicating excellent metallurgical bonding.

  16. Modifying AM60B Magnesium Alloy Die Cast Surfaces by Friction Stir Processing

    SciTech Connect

    Santella, Michael L; Feng, Zhili; Degen, Cassandra; Pan, Dr. Tsung-Yu

    2006-01-01

    These experiments were done to evaluate the feasibility of locally modifying the surface properties of magnesium alloys with friction-stir processing. The magnesium alloy used for the study was high-pressure die-cast AM60B, nominally Mg-6Al-0.13 Mn (wt. %). Friction-stir passes were made with a translation speed of 1.7 mm/s using tool-rotation speeds of 1,250 rpm or 2,500 rpm. Stir passes with good appearance were obtained under both conditions. In some cases up to five passes were overlapped on a single bar to produce stir zones with cross-sectional dimensions of about 1.5 mm x 10 mm. Metallographic examinations indicated that the stir zones were largely comprised of a magnesium solid solution with equiaxed grains on the order of 5-10 {micro}m in size. Hardness mapping showed that the stir zones experienced increases of 16-25% compared to the as-cast metal. Room-temperature testing showed that, compared to the cast metal, the stir zones had flow stresses nearly 20% higher with about twice the tensile elongation.

  17. A study on atomic diffusion behaviours in an Al-Mg compound casting process

    SciTech Connect

    Liu, Yongning; Chen, Yiqing; Yang, Chunhui

    2015-08-15

    Al and Mg alloys are main lightweight alloys of research interest and they both have superb material properties, i.e., low density and high specific strength, etc. Being different from Al alloys, the corrosion of Mg alloys is much more difficult to control. Therefore to combine merits of these two lightweight alloys as a composite-like structure is an ideal solution through using Al alloys as a protective layer for Mg alloys. Compound casting is a realistic technique to manufacture such a bi-metal structure. In this study, a compound casting technique is employed to fabricate bi-layered samples using Al and Mg and then the samples are analysed using electron probe micro-analyzer (EPMA) to determine diffusion behaviours between Al and Mg. The diffusion mechanism and behaviours between Al and Mg are studied numerically at atomic scale using molecular dynamics (MD) and parametric studies are conducted to find out influences of ambient temperature and pressure on the diffusion behaviours between Al and Mg. The results obtained clearly show the effectiveness of the compound casting process to increase the diffusion between Al and Mg and thus create the Al-base protection layer for Mg.

  18. Influence of macromolecular architecture on necking in polymer extrusion film casting process

    SciTech Connect

    Pol, Harshawardhan; Banik, Sourya; Azad, Lal Busher; Doshi, Pankaj; Lele, Ashish; Thete, Sumeet

    2015-05-22

    Extrusion film casting (EFC) is an important polymer processing technique that is used to produce several thousand tons of polymer films/coatings on an industrial scale. In this research, we are interested in understanding quantitatively how macromolecular chain architecture (for example long chain branching (LCB) or molecular weight distribution (MWD or PDI)) influences the necking and thickness distribution of extrusion cast films. We have used different polymer resins of linear and branched molecular architecture to produce extrusion cast films under controlled experimental conditions. The necking profiles of the films were imaged and the velocity profiles during EFC were monitored using particle tracking velocimetry (PTV) technique. Additionally, the temperature profiles were captured using an IR thermography and thickness profiles were calculated. The experimental results are compared with predictions of one-dimensional flow model of Silagy et al{sup 1} wherein the polymer resin rheology is modeled using molecular constitutive equations such as the Rolie-Poly (RP) and extended Pom Pom (XPP). We demonstrate that the 1-D flow model containing the molecular constitutive equations provides new insights into the role of macromolecular chain architecture on film necking.{sup 1}D. Silagy, Y. Demay, and J-F. Agassant, Polym. Eng. Sci., 36, 2614 (1996)

  19. The Impact of Melt-Conditioned Twin-Roll Casting on the Downstream Processing of an AZ31 Magnesium Alloy

    NASA Astrophysics Data System (ADS)

    Bayandorian, I.; Huang, Y.; Fan, Z.; Pawar, S.; Zhou, X.; Thompson, G. E.

    2012-03-01

    Melt conditioning by intensive shear was used prior to twin-roll casting of AZ31 magnesium alloy strip to promote heterogeneous nucleation and to provide a refined and uniform microstructure without severe macrosegregation. The cast strip was then processed by homogenization, hot rolling, and annealing, and its downstream processing was compared with a similar cast strip produced without melt conditioning. Melt conditioning produced strip with accelerated kinetics of recrystallization during homogenization and improved performance in hot rolling and improved tensile properties. An average tensile elongation of ~28 pct was achieved, which is substantially higher than the ~9 pct obtained for the strip produced without melt conditioning which is consistent with reported values (~6 pct to 16 pct). The as-cast, homogenized, and hot-rolled microstructures of the strip were characterized. The kinetics of homogenization and hot-rolling process have been discussed in detail.

  20. Effect of Process Parameters on Abnormal Grain Growth during Friction Stir Processing of a Cast Al Alloy

    SciTech Connect

    Jana, Saumyadeep; Mishra, Rajiv S.; Baumann, John A.; Grant, Glenn J.

    2010-11-25

    The effects of process parameters and friction stir processing (FSP) run configurations on the stability of nugget microstructure at elevated temperatures were evaluated. Cast plates of an Al-7Si- 0.6Mg alloy were friction stir processed using a combination of tool rotation rates and tool traverse speeds. All single pass runs showed some extent of abnormal grain growth (AGG), whereas multi-pass runs were more resistant to AGG. Additionally, higher tool rpm was found to be beneficial for controlling AGG. These effects were analyzed by comparing the result of this work with other published results and AGG models.

  1. Casting Technology.

    ERIC Educational Resources Information Center

    Wright, Michael D.; And Others

    1992-01-01

    Three articles discuss (1) casting technology as it relates to industry, with comparisons of shell casting, shell molding, and die casting; (2) evaporative pattern casting for metals; and (3) high technological casting with silicone rubber. (JOW)

  2. Effects of casting conditions and deformation processing on A356 aluminum and A356-20 vol. pct SiC composites

    NASA Technical Reports Server (NTRS)

    Rozak, G. A.; Lewandowski, J. J.; Wallace, J. F.; Altmisoglu, A.

    1992-01-01

    The effects of casting conditions and deformation processing on the mechanical properties of unreinforced A356 aluminum and A356-20 vol pct SiC composite were investigated by tensile properties in these compounds fabricated by either sand casting or squeeze casting techniques followed by hot working to 33, 50, 90, and 95 percent reductions. The evolution of the microstructure and values of tensile properties were evaluated for the cast materials in each of the hot worked conditions. It was found that, while the deformation processing of the sand-cast composite resulted in banding of the Al and SiC particles within the microstructure, such features were not observed in the squeeze-cast microstructure. The tensile strengths of the squeeze cast materials was found to be higher than those of the sand cast materials, for both the unreinforced and composite samples, while increased amounts of deformation were found to improve the ductility of the composite.

  3. Evaluation of Centrifugal Casting Process Parameters for In Situ Fabricated Functionally Gradient Fe-TiC Composite

    NASA Astrophysics Data System (ADS)

    Rahimipour, Mohammad Reza; Sobhani, Manoochehr

    2013-10-01

    A gradient Fe-TiC composite was successfully produced via combination of in situ reaction with centrifugal casting techniques. Additionally, some of the effective parameters of the centrifugal casting process have been studied. Cast iron and ferrotitanium, which were used as raw materials, were melted using a high-frequency induction furnace coupled with centrifugal equipment. The microstructure and phase characterization of the fabricated composite was studied by scanning electron microscopy, optical microscopy, and X-ray diffraction. The results show that the production of a pearlite matrix composite reinforced by TiC particles is feasible. The distribution of TiC in the pearlitic matrix is completely uneven as a result of density difference between molten medium and TiC in the centrifugal casting process.

  4. Quantitative characterization of processing-microstructure-properties relationships in pressure die-cast magnesium alloys

    NASA Astrophysics Data System (ADS)

    Lee, Soon Gi

    The central goal of this research is to quantitatively characterize the relationships between processing, microstructure, and mechanical properties of important high-pressure die-cast (HPDC) Mg-alloys. For this purpose, a new digital image processing technique for automatic detection and segmentation of gas and shrinkage pores in the cast microstructure is developed and it is applied to quantitatively characterize the effects of HPDC process parameters on the size distribution and spatial arrangement of porosity. To get better insights into detailed geometry and distribution of porosity and other microstructural features, an efficient and unbiased montage based serial sectioning technique is applied for reconstruction of three-dimensional microstructures. The quantitative microstructural data have been correlated to the HPDC process parameters and the mechanical properties. The analysis has led to hypothesis of formation of new type of shrinkage porosity called, "gas induced shrinkage porosity" that has been substantiated via simple heat transfer simulations. The presence of inverse surface macrosegregation has been also shown for the first time in the HPDC Mg-alloys. An image analysis based technique has been proposed for simulations of realistic virtual microstructures that have realistic complex pore morphologies. These virtual microstructures can be implemented in the object oriented finite elements framework to model the variability in the fracture sensitive mechanical properties of the HPDC alloys.

  5. EBSD Study on Grain Boundary and Microtexture Evolutions During Friction Stir Processing of A413 Cast Aluminum Alloy

    NASA Astrophysics Data System (ADS)

    Shamanian, Morteza; Mostaan, Hossein; Safari, Mehdi; Szpunar, Jerzy A.

    2016-07-01

    The as-cast Al alloys contain heterogeneous distributions of non-deforming particles due to non-equilibrium solidification effects. Therefore, these alloys have poor tribological and mechanical behaviors. It is well known that using friction stir processing (FSP), very fine microstructure is created in the as-cast Al alloys, while their wear resistance can be improved. In this research work, FSP is used to locally refine a surface layer of the coarse as-cast microstructure of cast A413 Al alloy. The main objective of this study is to investigate the effect of FSP on microstructure and microtexture evolutions in A413 cast Al alloy. The grain boundary character distribution, grain structure, and microtexture evolutions in as-cast and friction stir processed A413 Al alloy are analyzed by electron back scatter diffraction technique. It is found that with the FSP, the fraction of low ∑boundary such as ∑3, 7, and 9 are increased. The obtained results show that there are no deformation texture components in the structure of friction stir processed samples. However, some of the main recrystallization texture components such as BR and cubeND are formed during FSP which indicate the occurrence of dynamic recrystallization phenomenon due to the severe plastic deformation induced by the rotation of tool.

  6. EBSD Study on Grain Boundary and Microtexture Evolutions During Friction Stir Processing of A413 Cast Aluminum Alloy

    NASA Astrophysics Data System (ADS)

    Shamanian, Morteza; Mostaan, Hossein; Safari, Mehdi; Szpunar, Jerzy A.

    2016-05-01

    The as-cast Al alloys contain heterogeneous distributions of non-deforming particles due to non-equilibrium solidification effects. Therefore, these alloys have poor tribological and mechanical behaviors. It is well known that using friction stir processing (FSP), very fine microstructure is created in the as-cast Al alloys, while their wear resistance can be improved. In this research work, FSP is used to locally refine a surface layer of the coarse as-cast microstructure of cast A413 Al alloy. The main objective of this study is to investigate the effect of FSP on microstructure and microtexture evolutions in A413 cast Al alloy. The grain boundary character distribution, grain structure, and microtexture evolutions in as-cast and friction stir processed A413 Al alloy are analyzed by electron back scatter diffraction technique. It is found that with the FSP, the fraction of low ∑boundary such as ∑3, 7, and 9 are increased. The obtained results show that there are no deformation texture components in the structure of friction stir processed samples. However, some of the main recrystallization texture components such as BR and cubeND are formed during FSP which indicate the occurrence of dynamic recrystallization phenomenon due to the severe plastic deformation induced by the rotation of tool.

  7. Mechanical Strength and Failure Characteristics of Cast Mg-9 pctAl-1 pctZn Alloys Produced by a Heated-Mold Continuous Casting Process: Tensile Properties

    NASA Astrophysics Data System (ADS)

    Okayasu, Mitsuhiro; Takeuchi, Shuhei; Ohfuji, Hiroaki

    2014-11-01

    The mechanical properties and failure characteristics of a cast Mg alloy (AZ91: Mg-Al8.9-Zn0.6-Mn0.2) produced by a heated-mold continuous casting process (HMC) are investigated. In a modification of the original HMC process, the cooling of the liquid alloy by direct water spray is carried out in an atmosphere of high-purity argon gas. The HMC-AZ91 alloy exhibits excellent mechanical properties (high strength and high ductility) that are about twice as high as those for the same alloy produced by conventional gravity casting. The increased material strength and ductility of the HMC sample are attributed to nanoscale and microscale microstructural characteristics. The fine grains and tiny spherical eutectic structures ( e.g., Mg17Al12 and Al6Mn) distributed randomly in the matrix of the HMC alloy result in resistance to dislocation movement, leading to high tensile strength. Basal slip on (0001) planes in the relatively organized crystal orientation of the HMC alloy, as well as grain boundary sliding through tiny spherical eutectic structures, results in high ductility. Details of the failure mechanism under static loading in the HMC alloy are also discussed using failure models.

  8. Colloidal processing, tape casting and sintering of PLZT for development of piezoceramic/polymer interlayered composites

    NASA Astrophysics Data System (ADS)

    Feng, Jian-Huei

    Piezoceramic/polymer composites possess many advantages as compared to single-phase piezoceramics. One typical form of the composites is the interlayered structure, where the main requirement is to obtain thin, flat and dense ceramic sheets. Tape casting is a reliable process for producing such high-quality sheets. The colloidal processing of tape casting slurries is a critical step to achieve uniform ceramic bodies. Lanthanum-modified lead zirconate titanate (PLZT) was selected for making piezoceramic sheets due to its superior piezoelectric properties. The quality of green tapes depends mainly on the solvents and organic additives of tape casting slurries. The effects of xylenes/ethanol solvent mixtures on non-aqueous slurries were first investigated. Well-dispersed colloidal suspensions were obtained in xylenes-rich solvents with a minimum amount of menhaden fish oil as a dispersant. Adsorption of dispersant and PLZT solids content of unfired tapes are strongly affected by the solvent(s) utilized. Furthermore, when selecting solvent mixtures, one needs to consider other additives, such as binder that can affect the viscosity of slurries. Aqueous tape casting was performed using a polyelectrolyte dispersant, poly(vinyl alcohol) (PVA) binders and various plasticizers. Zeta potential, conductivity and viscosity of PLZT suspensions containing dispersant were characterized. The effects of plasticizers and binders on properties of unfired tapes were also investigated. The tapes made from low molecular weight plasticizers showed higher plasticity. Glycerol was shown to be the most effective plasticizer for PVA. Strong hydrogen bonding in high hydrolysis PVA led to high strength and high bulk density of green tapes, but also caused deformation of the tapes after drying. There are many challenges for sintering PLZT tapes due to volatilization of PbO component at high temperatures and fragility of thin tapes. By using the proper setter powders and the sandwich method

  9. Fabrication of TiO2/PU Superhydrophobic Film by Nanoparticle Assisted Cast Micromolding Process.

    PubMed

    Li, Jie; Zheng, Jianyong; Zhang, Jing; Feng, Jie

    2016-06-01

    Lotus-like surfaces have attracted great attentions in recent years for their wide applications in water repellency, anti-fog and self-cleaning. This paper introduced a novel process, nanoparticle assisted cast micromolding, to create polymer film with superhydrophobic surface. Briefly, waterborne polyurethane (WPU) sol and nano TiO2/WPU sol were each cast onto the featured surfaces of the poly(dimethylsiloxane) (PDMS) stamps replicated from fresh lotus leaves. After being dried and peeled off from the stamps, PU and TiO2/WPU replica films were created respectively. To the former, only high hydrophobic property was observed with static water contact angle (WCA) at 142.5 degrees. While to the later, superhydrophobic property was obtained with WCA more than 150 degrees and slide angle less than 3 degrees. Scanning electron microscopy (SEM) imaging showed that the PU replica film only had the micro-papillas and the TiO2/PU replica film not only had micro papillas but also had a large number of nano structures distributed on and between the micro-papillas. Such nano and micro hierarchical structures were very similar with those on the natural lotus leaf surface, thus was the main reason for causing superhydrophobic property. Although an elastic PDMS stamp from lotus leaf was used in herein process, hard molds may also be used in theory. This study supplied an alternative technique for large scale production of polymeric films with superhydrophobic. PMID:27427647

  10. The mechanical response of a uranium-nobium alloy: a comparison of cast versus wrought processing

    SciTech Connect

    Cady, Carl M; Gray, George T., III; Cerreta, Ellen K; Aikin, Robert M; Chen, Shuh - Rong; Trujillo, Carl P; Lopez, Mike F; Korzekwa, Deniece R; Kelly, Ann M

    2009-02-13

    A rigorous experimentation and validation program is being undertaken to create constitutive models that elucidate the fundamental mechanisms controlling plasticity in uranium-6 wt.% niobium alloys (U-6Nb). The first, 'wrought', material produced by processing a cast ingot I'ia forging and forming into plate was studied. The second material investigated is a direct cast U-6Nb alloy. The purpose of the investigation is to detennine the principal differences, or more importantly, similarities, between the two materials due to processing. It is well known that parameters like grain size, impurity size and chemistry affect the deformation and failure characteristics of materials. Metallography conducted on these materials revealed that the microstructures are quite different. Characterization techniques like tension, compression, and shear were performed to find the principal differences between the materials as a function of stress state. Dynamic characterization using a split Hopkinson pressure bar in conjunction with Taylor impact testing was conducted to derive and thereafter validate constitutive material models. The Mechanical Threshold Strength Model is shown to accurately capture the constitutive response of these materials and Taylor cylinder tests are used to provide a robust way to verify and validate the constitutive model predictions of deformation by comparing finite element simulations with the experimental results. The primary differences between the materials will be described and predictions about material behavior will be made.

  11. An evaluation of direct pressure sensors for monitoring the aluminum die casting process

    SciTech Connect

    Zhang, X.

    1997-12-31

    This study was conducted as part of the US Department of Energy (DOE) sponsored project Die Cavity Instrumentation. One objective of that project was to evaluate thermal, pressure, and gas flow process monitoring sensors in or near the die cavity as a means of securing improved process monitoring and control and better resultant part quality. The objectives of this thesis are to (1) evaluate a direct cavity pressure sensor in a controlled production campaign at the GM Casting Advanced Development Center (CADC) at Bedford, Indiana; and (2) develop correlations between sensor responses and product quality in terms of the casting weight, volume, and density. A direct quartz-based pressure sensor developed and marked by Kistler Instrument Corp. was acquired for evaluating as an in-cavity liquid metal pressure sensor. This pressure sensor is designed for use up to 700 C and 2,000 bars (29,000 psi). It has a pressure overload capacity up to 2,500 bars (36,250 psi).

  12. Numerical modelling of evaporation in a ceramic layer in the tape casting process

    NASA Astrophysics Data System (ADS)

    Jabbari, M.; Jambhekar, V. A.; Hattel, J. H.; Helmig, R.

    2016-06-01

    Evaporation of water from a ceramic layer is a key phenomenon in the drying process for the manufacturing of tape cast ceramics. This process contains mass, momentum and energy exchange between the porous medium and the free-flow region. In order to analyze such interaction processes, a Representative Elementary Volume (REV)-scale model concept is presented for coupling non-isothermal multi-phase compositional porous-media flow and single-phase compositional laminar free-flow. The preliminary results show the typical expected evaporation behaviour from a porous medium initially saturated with water, and its transport to the free-flow region according to the existent results from the literature.

  13. The development of ultrahigh strength low alloy cast steels with increased toughness

    NASA Astrophysics Data System (ADS)

    Lynch, Paul C.

    This work describes the initial work on the development of the next generation of ultrahigh strength low alloy (UHSLA) cast steels. These UHSLA cast steels have both ultrahigh strength levels and good impact toughness. The influence of heat treatment, secondary processing using hot isostatic processing (HIP), and chemical composition on the microstructure and properties of UHSLA cast steels have been evaluated. The extent of microsegregation reduction expected during the heat treatment of UHSLA cast steels has also been estimated by diffusion modeling. This new family of UHSLA cast steels is similar in composition and properties to UHSLA wrought steels. However, the heat treatment and secondary processing of the UHSLA cast steels is used to develop microstructures and properties typically developed through thermomechanical processing and heat treatment for wrought UHSLA steels. Two martensitic UHSLA steels, 4340+ (silicon modified 4340) and ES-1 were investigated for this study. For the 4340+ alloy, heat treatment variables evaluated include homogenization temperature and time, tempering temperature, and austempering temperature and time. For the ES-1 alloy, heat treatment variables evaluated include homogenization temperature and time, austenization temperature, cryogenic treatment, and tempering temperature. The effect of high temperature hot isostatic processing (HIP) on the 4340+ and ES- 1 alloys was also investigated. Tensile properties, charpy v-notch impact toughness (CVN), microstructures, and fractographs have all been characterized after heat treatment. The effects of HIP on microporosity reduction in the ES-1 alloy were also investigated. The experiments carried out on the investment cast 4340+ alloy have shown that increasing the homogenization temperature can increase CVN without changing the ultimate tensile strength (UTS) or yield strength (YS) of the cast material. By replacing the homogenization step in the conventional heat treatment process with

  14. Semi-quantitative predictions of hot tearing and cold cracking in aluminum DC casting using numerical process simulator

    NASA Astrophysics Data System (ADS)

    Subroto, T.; Miroux, A.; Mortensen, D.; M'Hamdi, M.; Eskin, D. G.; Katgerman, L.

    2012-07-01

    Cracking is one of the most critical defects that may occur during aluminum direct-chill (DC) casting. There are two types of cracking typical of DC casting: hot tearing and cold cracking. To study and predict such defects, currently we are using a process simulator, ALSIM. ALSIM is able to provide semi-quantitative predictions of hot tearing and cold cracking susceptibility. In this work, we performed benchmark tests using predictions of both types of cracks and experimental results of DC casting trials. The trials series resulted in billets with hot tearing as well as cold cracking. The model was also used to study the influence of several casting variables such as casting speed and inlet geometry with respect to the cracking susceptibility in the ingots. In this work, we found that the sump geometry was changed by the feeding scheme, which played an important role in hot tear occurrence. Moreover, increasing the casting speed also increased the hot tear and cold crack susceptibility. In addition, from the result of simulation, we also observed a phenomenon that supported the hypotheses of connection between hot tearing and cold cracking.

  15. Development of Cast Alumina-forming Austenitic Stainless Steel Alloys for use in High Temperature Process Environments

    SciTech Connect

    Muralidharan, Govindarajan; Yamamoto, Yukinori; Brady, Michael P; Pint, Bruce A; Pankiw, Roman; Voke, Don

    2015-01-01

    There is significant interest in the development of alumina-forming, creep resistant alloys for use in various industrial process environments. It is expected that these alloys can be fabricated into components for use in these environments through centrifugal casting and welding. Based on the successful earlier studies on the development of wrought versions of Alumina-Forming Austenitic (AFA) alloys, new alloy compositions have been developed for cast products. These alloys achieve good high-temperature oxidation resistance due to the formation of protective Al2O3 scales while multiple second-phase precipitation strengthening contributes to excellent creep resistance. This work will summarize the results on the development and properties of a centrifugally cast AFA alloy. This paper highlights the strength, oxidation resistance in air and water vapor containing environments, and creep properties in the as-cast condition over the temperature range of 750°C to 900°C in a centrifugally cast heat. Preliminary results for a laboratory cast AFA composition with good oxidation resistance at 1100°C are also presented.

  16. Aluminum-Silicon Alloy Having Improved Properties At Elevated Temperatures and Process for Producing Cast Articles Therefrom

    NASA Technical Reports Server (NTRS)

    Lee, Jonathan A. (Inventor); Chen, Po-Shou (Inventor)

    2002-01-01

    A process for making a cast article from an aluminum alloy includes first casting an article from an alloy having the following composition, in weight percent: Silicon 11.0-14.0, Copper 5.6-8.0, Iron 0-0.8, Magnesium 0.5-1.5, Nickel 0.05-0.9, Manganese 0-1.0, Titanium 0.05-1.2, Zirconium 0.12-1.2, Vanadium 0.05-1.2, Zinc 0.05-0.9, Strontium 0.001-0.1, Aluminum balance . In this alloy the ratio of silicon to magnesium is 10 to 25, and the ratio of copper to magnesium is 4 to 15. After an article is cast from the alloy, the cast article is aged at a temperature within the range of 400F to 500F for a time period within the range of four to 16 hours. It has been found especially advantageous if the cast article is first exposed to a solutionizing step prior to the aging step. This solutionizing step is carried out by exposing the cast article to a temperature within the range of 900F to 1000F for a time period of fifteen minutes to four hours. It has also been found to be especially advantageous if the solutionizing step is followed directly with a quenching step, wherein the cast article is quenched in a quenching medium such as water at a temperature within the range of 120F to 300F. The resulting cast article is suitable in a number of high temperature applications, such as heavy-duty pistons for internal combustion engines.

  17. Annealing of chromium oxycarbide coatings deposited by plasma immersion ion processing (PIIP) for aluminum die casting

    NASA Astrophysics Data System (ADS)

    Peters, A. M.; He, X. M.; Trkula, M.; Nastasi, M.

    2001-04-01

    Chromium oxycarbide coatings have been investigated for use as non-wetting coatings for aluminum die casting. This paper examines Cr-C-O coating stability and non-wetability at elevated temperatures for extended periods. Coatings were deposited onto 304 stainless steel from chromium carbonyl [Cr(CO) 6] by plasma immersion ion processing. The coatings were annealed in air at an aluminum die casting temperature of 700°C up to 8 h. Coatings were analyzed using resonant ion backscattering spectroscopy, nanoindentation and pin-on-disk tribometry. Molten aluminum was used to determine coating wetting and contact angle. Results indicate that the surface oxide layer reaches a maximum thickness of 900 nm. Oxygen concentrations in the coatings increased from 24% to 34%, while the surface concentration rose to almost 45%. Hardness values ranged from 22.1 to 6.7 GPa, wear coefficients ranged from 21 to 8×10 -6 mm3/ Nm and contact angles ranged from 156° to 127°.

  18. Self-resolution of alcohol problems as a process of investing and re-investing in self.

    PubMed

    Finfgeld, D L

    1999-08-01

    Resolution of alcohol problems without formal treatment or participation in support groups was studied using a grounded theory approach. Thirteen former problem drinkers and their close associates were interviewed, and verbatim transcripts were analyzed using grounded theory methods. The core of self-resolving alcohol problems involves investing and/or reinvesting in self to gain or regain the essence of who or what one wants to be. Self-resolvers tend to independently change for their own benefit rather than the benefit of others, and personal resources may promote or delay the process. The effort required to self-resolve drinking problems varies, and close associates tend to be minority investors in the process. Input from health-care providers regarding the health-related hazards of drinking are largely ignored because threats to who or what one wants to be are perceived as more significant. As such, clinical interventions should emphasize personally relevant threats to self versus focusing solely on the physical consequences of alcohol abuse. PMID:10478499

  19. On the evolution of unsteady disturbances in continuous strip casting processes

    NASA Astrophysics Data System (ADS)

    Kluwick, A.; Scheichl, St.

    1997-12-01

    Continuous solidification processes in thin layers of molten metal are of central importance in many fields of modern metallurgical engineering. This paper deals with unsteady disturbances possibly emerging at the free surface or the phase boundary within the solidification zone of a horizontal strip casting process. Assuming that the wave lengths of the disturbances are large compared to the characteristic depth of the melt, we can apply governing equations for one-dimensional flow. Furthermore, we assume the amplitudes of the disturbances to be so small that their evolution can be regarded as weakly nonlinear. Since unsteady wave propagation phenomena can arise from temperature variations as well as from the excitation of waves at the free surface or the solidification front, both mechanisms will be studied in the following. In the latter case the disturbances at the surface are found to be governed by the inviscid Burgers equations with varying coefficients and will then, in general, develop shock discontinuities.

  20. A fast and efficient adaptive parallel ray tracing based model for thermally coupled surface radiation in casting and heat treatment processes

    NASA Astrophysics Data System (ADS)

    Fainberg, J.; Schaefer, W.

    2015-06-01

    A new algorithm for heat exchange between thermally coupled diffusely radiating interfaces is presented, which can be applied for closed and half open transparent radiating cavities. Interfaces between opaque and transparent materials are automatically detected and subdivided into elementary radiation surfaces named tiles. Contrary to the classical view factor method, the fixed unit sphere area subdivision oriented along the normal tile direction is projected onto the surrounding radiation mesh and not vice versa. Then, the total incident radiating flux of the receiver is approximated as a direct sum of radiation intensities of representative “senders” with the same weight factor. A hierarchical scheme for the space angle subdivision is selected in order to minimize the total memory and the computational demands during thermal calculations. Direct visibility is tested by means of a voxel-based ray tracing method accelerated by means of the anisotropic Chebyshev distance method, which reuses the computational grid as a Chebyshev one. The ray tracing algorithm is fully parallelized using MPI and takes advantage of the balanced distribution of all available tiles among all CPU's. This approach allows tracing of each particular ray without any communication. The algorithm has been implemented in a commercial casting process simulation software. The accuracy and computational performance of the new radiation model for heat treatment, investment and ingot casting applications is illustrated using industrial examples.

  1. Machinability of Austempered Ductile Iron (ADI) Produced by Integrated Green Technology of Continuous Casting-Heat Treatment Processes

    SciTech Connect

    Meena, A.; El Mansori, M.; Ghidossi, P.

    2011-01-17

    This study presents the novel processing technique known as continuous casting-heat treatment processes to produce Austempered Ductile Iron (ADI) which is a new class of ductile iron. ADI is characterized by improved mechanical properties but has low machinability as compared to other cast irons and steel of similar strength. The novel technique is developed by the integration of casting (in die casting) and heat treatment processes in foundry to save cost energy and time. Specimens just after casting were austenitized at 930 deg. C for 90 min and then austempered in fluidized bed at 380 deg. C for 90 and 120 min. Hence, the effect of austempering time on the morphology of retained austenite and mechanical properties of the material were examined and compared with conventionally produced ADI. Drilling tests were then carried out to evaluate the machinability of ADI in terms of cutting forces, chip micro-hardness, chip morphology and surface roughness. The mechanical properties of ADI austempered for 120 min have found to be better as compare to the ADI austempered for 90 min.

  2. Machinability of Austempered Ductile Iron (ADI) Produced by Integrated Green Technology of Continuous Casting-Heat Treatment Processes

    NASA Astrophysics Data System (ADS)

    Meena, A.; El Mansori, M.; Ghidossi, P.

    2011-01-01

    This study presents the novel processing technique known as continuous casting-heat treatment processes to produce Austempered Ductile Iron (ADI) which is a new class of ductile iron. ADI is characterized by improved mechanical properties but has low machinability as compared to other cast irons and steel of similar strength. The novel technique is developed by the integration of casting (in die casting) and heat treatment processes in foundry to save cost energy and time. Specimens just after casting were austenitized at 930° C for 90 min and then austempered in fluidized bed at 380° C for 90 and 120 min. Hence, the effect of austempering time on the morphology of retained austenite and mechanical properties of the material were examined and compared with conventionally produced ADI. Drilling tests were then carried out to evaluate the machinability of ADI in terms of cutting forces, chip micro-hardness, chip morphology and surface roughness. The mechanical properties of ADI austempered for 120 min have found to be better as compare to the ADI austempered for 90 min.

  3. Analysis and Evaluation of Novel Al-Mg-Sc-Zr Aerospace Alloy Strip Produced Using the Horizontal Single Belt Casting (HSBC) Process

    NASA Astrophysics Data System (ADS)

    Ge, Sa; Celikin, Mert; Isac, Mihaiela; Guthrie, Roderick I. L.

    2015-04-01

    Horizontal single belt casting (HSBC) is a near net shape casting process in which molten metal is directly cast into thin strips, at high cooling rates (order of several 100 °C/s), with the potential for high volume, friction free, continuous production of metal strips. This casting process was used in the present work to produce strips of Al-Mg alloys in the AA5000 series, with additions of Sc and Zr. Such aluminum alloys show exceptional potential as a structural material for transportation/aerospace applications. To demonstrate the suitability of the HSBC process to manufacture competitive strip products of Al-Mg-Sc-Zr, the mechanical properties and microstructures of the strips produced using the HSBC process were compared with conventionally cast products. The effects of annealing on the mechanical properties of the strip-cast Al-Mg-Sc-Zr alloys were also investigated.

  4. Thermal casting process for the preparation of anisotropic membranes and the resultant membrane

    DOEpatents

    Caneba, Gerard T. M.; Soong, David S.

    1987-01-01

    A method for providing anisotropic polymer membranes from a binary polymer/solvent solution using a thermal inversion process. A homogeneous binary solution is cast onto a support and cooled in such a way as to provide a differential in cooling rate across the thickness of the resulting membrane sheet. Isotropic or anisotropic structures of selected porosities can be produced, depending on the initial concentration of polymer in the selected solvent and on the extent of the differential in cooling rate. This differential results in a corresponding gradation in pore size. The method may be modified to provide a working skin by applying a rapid, high-temperature pulse to redissolve a predetermined thickness of the membrane at one of its faces and then freezing the entire structure.

  5. Wear properties of compact graphite cast iron with bionic units processed by deep laser cladding WC

    NASA Astrophysics Data System (ADS)

    Zhou, Hong; Zhang, Peng; Sun, Na; Wang, Cheng-tao; Lin, Peng-yu; Ren, Lu-quan

    2010-08-01

    By simulating the cuticles of some soil animals, the wear resistance of compact graphite cast iron (CGI) processed by laser remelting gets a conspicuous improvement. In order to get a further anti-wear enhancement of CGI, a new method of deep laser cladding was used to process bionic units. By preplacing grooves then filling with WC powders and laser cladding, the bionic units had a larger dimension in depth and higher microhardness. Fe powder with different proportions from 30% (wt.) to 60% (wt.) was added into WC before laser processing for a good incorporation with CGI substrate. The improved laser cladding units turned out to induce higher wear resistance in comparison with laser remelting ones. The depth of the layer reached up to 1 mm. The results of dry sliding wear tests indicated that the specimen processed by laser cladding has a remarkable improvement than the ones processed by laser remelting. It should be noted that the wear mass loss was essentially dependent on the increase in WC proportion.

  6. Simple, low-cost planar flow casting machine for rapid solidification processing

    NASA Astrophysics Data System (ADS)

    Smith, M. T.; Saletore, M.

    1986-08-01

    The design, fabrication, and operation of a relatively simple low-cost planar flow casting (PFC) machine optimized for small-batch processing were investigated by the Bureau of Mines. Several design features found beneficial to PFC process operation include: a ground nozzle stopper to retain the alloy charge during melting; a remote, large-volume pressure vessel connected to the crucible gas system to reduce temperature-induced pressure fluctuations; and the use of a nested induction coil that allows both the melt charge and the crucible reservoir to be located close to the cooling wheel. The results of several PFC process runs are provided showing typical values of the cooling wheel surface velocity, crucible ejection pressure, and crucible nozzle clearance gap. Examination of the rapidly solidified, Fe-based ribbons for thickness, dimensional uniformity, and atomic structure indicated that good quality glassy ribbon could be produced with proper selection of the controllable process variables. In addition, single-variable linear regression analysis was used to determined the effect of each process variable on the resulting ribbon thickness.

  7. Low-resolution FTIR continuous monitoring/process control system to minimize HCl emissions in aluminum casting operations

    NASA Astrophysics Data System (ADS)

    Dunder, Thomas A.

    1999-12-01

    In a Department of Energy funded project, a low resolution Fourier Transform IR Continuous Emissions Monitoring (FTIR CEM) and Process Control system was developed and evaluated for use in minimizing HCl emissions during aluminum casting operations. In the casting process, molten aluminum is treated by fluxing with chlorine to remove alkali and hydrogen impurities. The industry has traditionally used a stoichiometric excess of chlorine to ensure metal quality, with resulting atmospheric emissions of HCl. The FTIR system can potentially be used to reduce emission when employed as a closed-loop process control device to monitor the HCl concentration and thereby reduce chlorine usage while maintaining product quality. In the initial project phase, tests were conducted under varying process conditions at a pilot-scale casting facility. The goals of these test included demonstrating that the FTIR monitor could provide closed-loop control of chlorine use, correlating HCl emission with metal quality, and verifying that the instrumentation could operate under harsh casting facility conditions. The system will subsequently be tested at two aluminum production facilities. This paper summarizes the results from the initial evaluation of the FTIR CEM/Process Control system.

  8. Effect of Rotational Speeds on the Cast Tube During Vertical Centrifugal Casting Process on Appearance, Microstructure, and Hardness Behavior for Al-2Si Alloy

    NASA Astrophysics Data System (ADS)

    Shailesh Rao, A.; Tattimani, Mahantesh S.; Rao, Shrikantha S.

    2015-04-01

    The flow of molten metal plays a crucial role in determining casting quality. During rotation of the mold, melt flow around its inner circumference determines the final configurations and properties of the cast tube. In this paper, Al-2Si alloy is cast in the vertical mold at the various rotational speeds of the mold. The uniform cylinder tube is formed at a rotational speed of 1000 rpm, while before and beyond this speed, irregular-shaped cast tube is formed. Finally, fine structured grain size with high hardness value is found in uniform cast tube compared with others.

  9. ToxCast Workflow: High-throughput screening assay data processing, analysis and management (SOT)

    EPA Science Inventory

    US EPA’s ToxCast program is generating data in high-throughput screening (HTS) and high-content screening (HCS) assays for thousands of environmental chemicals, for use in developing predictive toxicity models. Currently the ToxCast screening program includes over 1800 unique c...

  10. Study on Venture Capital Investment Risk Avoiding Base on Option Pricing in Agricultural Production and Processing Enterprises

    NASA Astrophysics Data System (ADS)

    Zhang, Xubo

    This paper uses the approaches and models of option theory to analyze two-stage venture capital investment in agricultural production and processing enterprises decision-making under uncertainty. Mathematics expressions of this two-stage venture capital investment decision-making are presented. An option value model about two-stage venture capital investment decision-making base on options pricing theory under the uncertainty is presented. Get the solution of option pricing model which we present.

  11. Microstructure Analysis on 6061 Aluminum Alloy after Casting and Diffuses Annealing Process

    NASA Astrophysics Data System (ADS)

    Wang, H. Q.; Sun, W. L.; Xing, Y. Q.

    One factory using semi-continuous casting process produce the ф200×6000 mm 6061 aluminium alloy barstock, and then rotary forged for car wheels. 6061 distorting aluminium alloy is an forged aluminum alloy, and mainly containing Mg, Si, Cu and other alloying elements. The main strengthening phase is Mg2Si, and also has few phase of (FeMn) 3Si2Al15. In order to eliminate the segregation and separation which present in the crystal boundary, and make the distortion to be uniform, and does not present ear and fracture defects after the forging. So the 6061 distorting aluminium alloy adopt the diffusion annealing heat treatment before the forging process.According to the current conditions, we use the diffusion annealing which have the different heating temperature and different holding time.The best process we can obtain from the test which can improve the production efficiency and reduce the material waste, improve the mechanical properties, and eliminate the overheated film on the surface.Then,we using OM,SEM and EDS to analyse the microstructure and the chemical composition of compound between the surface and centre. The result shows that the amount of segregation were different in the surface and in the center, and the different diffusion annealing can cause the phase change in the surface and the center.

  12. The study of flow pattern and phase-change problem in die casting process

    NASA Technical Reports Server (NTRS)

    Wang, T. S.; Wei, H.; Chen, Y. S.; Shang, H. M.

    1996-01-01

    The flow pattern and solidification phenomena in die casting process have been investigated in the first phase study. The flow pattern in filling process is predicted by using a VOF (volume of fluid) method. A good agreement with experimental observation is obtained for filling the water into a die cavity with different gate geometry and with an obstacle in the cavity. An enthalpy method has been applied to solve the solidification problem. By treating the latent heat implicitly into the enthalpy instead of explicitly into the source term, the CPU time can be reduced at least 20 times. The effect of material properties on solidification fronts is tested. It concludes that the dependence of properties on temperature is significant. The influence of the natural convection over the diffusion has also been studied. The result shows that the liquid metal solidification phenomena is diffusion dominant, and the natural convection can affect the shape of the interface. In the second phase study, the filling and solidification processes will be considered simultaneously.

  13. Achieving Investment Autonomy.

    ERIC Educational Resources Information Center

    Flynn, Jeffrey B.

    1988-01-01

    Public investors can lower commissions through investment autonomy, that is, implementing the investment decision process without outside input. Details some techniques for fine-tuning the investment process. (MLF)

  14. Effects of Processing Parameters on the Fabrication of Copper Cladding Aluminum Rods by Horizontal Core-Filling Continuous Casting

    NASA Astrophysics Data System (ADS)

    Su, Ya-Jun; Liu, Xin-Hua; Huang, Hai-You; Wu, Chun-Jing; Liu, Xue-Feng; Xie, Jian-Xin

    2011-02-01

    Copper cladding aluminum (CCA) rods with a diameter of 30 mm and a sheath thickness of 3 mm were fabricated by horizontal core-filling continuous casting (HCFC) technology. The effects of key processing parameters, such as the length of the mandrel tube of composite mold, aluminum casting temperature, flux of the secondary cooling water, and mean withdrawing speed were optimized based on some quality criteria, including the uniformity of the sheath thickness, integrality of the rods, and thickness of the interface. The causes of internal flaws formation of CCA rods were also discussed. The results showed that the continuity of the liquid aluminum core-filling process and the interface reaction control between solid copper and liquid aluminum were two key problems that strongly affected the stability of the casting process and the product quality. Our research indicated that for the CCA rod with the previously mentioned size, the optimal length of mandrel tube was 210 mm. A shorter mandrel tube allowed of easier erosion at the interface, which led to a nonuniform sheath thickness. Conversely, it tended to result in a discontinuous filling process of liquid aluminum, which causes shrinkage or cold shuts. The optimal casting temperatures of copper and aluminum were 1503 K (1230 °C) and 1043 K to 1123 K (770 °C to 850 °C), respectively. When the casting temperature of aluminum was below 1043 K (770 °C), the casting process would be discontinuous, resulting in shrinkages or cold shuts. Nevertheless, when the casting temperature of aluminum was higher than 1123 K (850 °C), a severe interface reaction between solid copper and liquid aluminum would occur. The proper flux of the secondary cooling water and the mean withdrawing speed were determined as 600 to 800 L/h and 60 to 87 mm/min, respectively. In the previously mentioned proper ranges of processing parameters, the interfacial shear strengths of CCA rods were 40.5 to 67.9 MPa.

  15. Anisotropic constitutive model and FE simulation of the sintering process of slip cast traditional porcelain

    NASA Astrophysics Data System (ADS)

    Sarbandi, B.; Besson, J.; Boussuge, M.; Ryckelynck, D.

    2010-06-01

    Slip cast ceramic components undergo both sintering shrinkage and creep deformation caused by gravity during the firing cycle. In addition sintering may be anisotropic due to the development of preferential directions during slip casting. Both phenomena induce complex deformations of parts which make the design of casting molds difficult. To help solving this problem, anisotropic constitutive equations are proposed to represent the behavior of the ceramic compacts during sintering. The model parameters are identified using tests allowing to characterize both sintering and creep. The model was implemented in a finite element software and used to simulate the deformation of a traditional ceramic object during sintering.

  16. Anisotropic constitutive model and FE simulation of the sintering process of slip cast traditional porcelain

    SciTech Connect

    Sarbandi, B.; Besson, J.; Boussuge, M.; Ryckelynck, D.

    2010-06-15

    Slip cast ceramic components undergo both sintering shrinkage and creep deformation caused by gravity during the firing cycle. In addition sintering may be anisotropic due to the development of preferential directions during slip casting. Both phenomena induce complex deformations of parts which make the design of casting molds difficult. To help solving this problem, anisotropic constitutive equations are proposed to represent the behavior of the ceramic compacts during sintering. The model parameters are identified using tests allowing to characterize both sintering and creep. The model was implemented in a finite element software and used to simulate the deformation of a traditional ceramic object during sintering.

  17. Large Eddy Simulation of Transient Flow, Solidification, and Particle Transport Processes in Continuous-Casting Mold

    NASA Astrophysics Data System (ADS)

    Liu, Zhongqiu; Li, Linmin; Li, Baokuan; Jiang, Maofa

    2014-07-01

    The current study developed a coupled computational model to simulate the transient fluid flow, solidification, and particle transport processes in a slab continuous-casting mold. Transient flow of molten steel in the mold is calculated using the large eddy simulation. An enthalpy-porosity approach is used for the analysis of solidification processes. The transport of bubble and non-metallic inclusion inside the liquid pool is calculated using the Lagrangian approach based on the transient flow field. A criterion of particle entrapment in the solidified shell is developed using the user-defined functions of FLUENT software (ANSYS, Inc., Canonsburg, PA). The predicted results of this model are compared with the measurements of the ultrasonic testing of the rolled steel plates and the water model experiments. The transient asymmetrical flow pattern inside the liquid pool exhibits quite satisfactory agreement with the corresponding measurements. The predicted complex instantaneous velocity field is composed of various small recirculation zones and multiple vortices. The transport of particles inside the liquid pool and the entrapment of particles in the solidified shell are not symmetric. The Magnus force can reduce the entrapment ratio of particles in the solidified shell, especially for smaller particles, but the effect is not obvious. The Marangoni force can play an important role in controlling the motion of particles, which increases the entrapment ratio of particles in the solidified shell obviously.

  18. Process-directed self-assembly of multiblock copolymers: Solvent casting vs spray coating

    NASA Astrophysics Data System (ADS)

    Tang, Q.; Tang, J.; Müller, M.

    2016-07-01

    Using computer simulation of a soft, coarse-grained model and self-consistent field theory we investigate how collapsed, globular chain conformations in the initial stages of structure formation, which are produced by spray-coating, affect the single-chain structure and morphology of microphase-separated multiblock copolymers. Comparing spray-coated films with films that start from a disordered state of Gaussian chains, we observe that the collapsed molecular conformations in the initial stage give rise to (1) a smaller fraction of blocks that straddle domains (bridges), (2) a significant reduction of the molecular extension normal to the internal interfaces, and (3) a slightly larger lamellar domain spacing in the final morphology. The relaxation of molecular conformations towards equilibrium is very protracted for both processes - solvent casting and spray coating. These findings illustrate that the process conditions of the copolymer materials may significantly affect materials properties (such as mechanical properties) because the system does not reach thermal equilibrium on the relevant time scales.

  19. Metal particle compaction during drop-substrate impact for inkjet printing and drop-casting processes

    NASA Astrophysics Data System (ADS)

    Clancy, I.; Amarandei, G.; Nash, C.; Glowacki, B. A.

    2016-02-01

    Direct coating methods using metal particles from aqueous solutions or solvent-based inks become central in the roll-to-roll fabrication processes as these methods can lead to continuous or pre-defined conductive layers on a large variety of substrates. For good electrical conductivity, the metal particles have to be brought into contact, and traditionally, additional sintering treatments are required. Such treatments can degrade the sensitive substrates as paper or polymer films. In this study, the possibility of obtaining conductive layers at room temperature is investigated for direct coating methods with an emphasis on drop-casting and inkjet printing. Thus, it is shown that electrical conductive layers can be achieved if the metal particles can compact during the drop-substrate impact interaction. It is theoretically shown that the compaction process is directly related to the particle and ink drop size, the initial fractional particle loading of the ink, solvent viscosity, and drop velocity. The theoretical predictions on compaction are experimentally validated, and the particle compaction's influence on changes in the electrical conductivity of the resulting layers is demonstrated.

  20. LLNL casting technology

    SciTech Connect

    Shapiro, A.B.; Comfort, W.J. III

    1994-01-01

    Competition to produce cast parts of higher quality, lower rejection rate, and lower cost is a fundamental factor in the global economy. To gain an edge on foreign competitors, the US casting industry must cut manufacturing costs and reduce the time from design to market. Casting research and development (R&D) are the key to increasing US compentiveness in the casting arena. Lawrence Livermore National Laboratory (LLNL) is the home of a wide range of R&D projects that push the boundaries of state-of-the art casting. LLNL casting expertise and technology include: casting modeling research and development, including numerical simulation of fluid flow, heat transfer, reaction/solidification kinetics, and part distortion with residual stresses; special facilities to cast toxic material; extensive experience casting metals and nonmetals; advanced measurement and instrumentation systems. Department of Energy (DOE) funding provides the leverage for LLNL to collaborate with industrial partners to share this advanced casting expertise and technology. At the same time, collaboration with industrial partners provides LLNL technologists with broader insights into casting industry issues, casting process data, and the collective, experience of industry experts. Casting R&D is also an excellent example of dual-use technology; it is the cornerstone for increasing US industrial competitiveness and minimizing waste nuclear material in weapon component production. Annual funding for casting projects at LLNL is $10M, which represents 1% of the total LLNL budget. Metal casting accounts for about 80% of the funding. Funding is nearly equally divided between development directed toward US industrial competitiveness and weapon component casting.

  1. LLNL casting technology

    NASA Astrophysics Data System (ADS)

    Shapiro, A. B.; Comfort, W. J., III

    1994-01-01

    Competition to produce cast parts of higher quality, lower rejection rate, and lower cost is a fundamental factor in the global economy. To gain an edge on foreign competitors, the US casting industry must cut manufacturing costs and reduce the time from design to market. Casting research and development (R&D) are the key to increasing US competiveness in the casting arena. Lawrence Livermore National Laboratory (LLNL) is the home of a wide range of R&D projects that push the boundaries of state-of-the art casting. LLNL casting expertise and technology include: casting modeling research and development, including numerical simulation of fluid flow, heat transfer, reaction/solidification kinetics, and part distortion with residual stresses; special facilities to cast toxic material; extensive experience casting metals and nonmetals; advanced measurement and instrumentation systems. Department of Energy (DOE) funding provides the leverage for LLNL to collaborate with industrial partners to share this advanced casting expertise and technology. At the same time, collaboration with industrial partners provides LLNL technologists with broader insights into casting industry issues, casting process data, and the collective experience of industry experts. Casting R&D is also an excellent example of dual-use technology; it is the cornerstone for increasing US industrial competitiveness and minimizing waste nuclear material in weapon component production. Annual funding for casting projects at LLNL is $10M, which represents 1% of the total LLNL budget. Metal casting accounts for about 80% of the funding. Funding is nearly equally divided between development directed toward US industrial competitiveness and weapon component casting.

  2. Experimental investigation of the start-up phase during direct chill and low frequency electromagnetic casting of 6063 aluminum alloy processes

    NASA Astrophysics Data System (ADS)

    Wang, Xiangjie; Zhang, Haitao; Zhao, Zhihao; Zhu, Qingfeng; Wang, Gaosong; Jiang, Huixue; Cui, Jianzhong

    2010-06-01

    On the basis of conventional hot-top casting and Casting, Refining and Electromagnetic process, a lower frequency electromagnetic field was applied during the conventional hot-top casting process. Nine thermocouples (type K) were introduced into the metal to study the temperature profile in the ingot during the start-up phase of casting process. The experimental results show that under the effect of the low frequency electromagnetic filed, the heat transfer is changed greatly and the film boiling disappears, which could restrain the formation of fine subsurface cracks; the sump is shallow, and the macrostructure of the ingot butt is fine during the start-up phase of direct chill casting process.

  3. The influence of cooling conditions on grain size, secondary phase precipitates and mechanical properties of biomedical alloy specimens produced by investment casting.

    PubMed

    Kaiser, R; Williamson, K; O'Brien, C; Ramirez-Garcia, S; Browne, D J

    2013-08-01

    The objective of this work was to investigate and evaluate the effect of the cooling environment on the microstructure, secondary phase precipitates and mechanical properties of an as-cast cobalt alloy. The microstructure of castings has a large bearing on the mechanical properties, grain size, porosity and the morphology of carbide precipitates are thought to influence hardness, tensile strength and ductility. It is postulated that a greater understanding of microstructure and secondary phase precipitate response to casting parameters could lead to the optimisation of casting parameters and serve to reduce the requirement of thermo-mechanical treatments currently applied to refine as-cast structures and achieve adequate mechanical properties. Thermal analysis was performed to determine the critical stages of cooling. Ten millimetre diameter cylindrical specimens which could be machined into tension test specimens were cast and cooled under different conditions to impose different cooling rates. Analytical techniques such as optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDX), tensile testing and micro-hardness testing were used to study the specimens. Parameters studied include grain size, secondary dendrite arm spacing, secondary phase precipitates, porosity, hardness, ultimate tensile strength, yield strength and elongation. The microstructure of as-cast Co-28Cr-6Mo was found to consist of a dendritic matrix with secondary phases precipitated at grain boundaries and interdendritic zones. These secondary phase precipitates consist of carbides, rich in chromium and molybdenum. The size and area fraction of carbides was found to decrease significantly with increasing cooling rate while the micro-porosity was only marginally affected. The as-cast grains are illustrated for the first time showing a significant difference in size between insulated and naturally cooled specimens. The secondary dendrite arm spacing was

  4. Process for casting hard-faced, lightweight camshafts and other cylindrical products

    DOEpatents

    Hansen, Jeffrey S.; Turner, Paul C.; Argetsinger, Edward R.; Wilson, Rick D.

    1996-01-01

    A process for casting a hard-faced cylindrical product such as an automobile camshaft includes the steps of: (a) preparing a composition formed from a molten base metal and an additive in particle form and having a hardness value greater than the hardness value of the base metal; (b) introducing the composition into a flask containing a meltable pattern of a cylindrical product such as an automobile camshaft to be manufactured and encased in sand to allow the composition to melt the pattern and assume the shape of the pattern within the sand; and (c) rotating the flask containing the pattern about the longitudinal axes of both the flask and the pattern as the molten base metal containing the additive in particle form is introduced into the flask to cause particles of the additive entrained in the molten base metal to migrate by centrifugal action to the radial extremities of the pattern and thereby provide a cylindrical product having a hardness value greater at it's radial extremities than at its center when the molten base metal solidifies.

  5. Fabrication of glass photonic crystal fibers with a die-cast process

    NASA Astrophysics Data System (ADS)

    Guiyao, Zhou; Zhiyun, Hou; Shuguang, Li; Lantian, Hou

    2006-06-01

    We demonstrate a novel method for the fabrication of glass photonic crystal fibers (PCFs) with a die-cast process. SF6 glass is used as the material for PCFs, and the die is made of heat-resisting alloy steel, whose inner structure matches the PCF's structure. The die is put vertically in the vessel with SF6 glass, and the vacuum hose is attached to the top of the die. The die and glass are put in the furnace to heat at 870 K. The die is slowly filled with the softening glass under vacuum conduction until it is full. It is kept in the furnace to anneal at a rate of 20 K/h to remove the thermal stress that could lead to cracks. The outer tube of the die is taken apart when its temperature is close to room temperature, and the fused glass bundle is etched in an acidic solution to remove the heat-resisting alloy steel rods. Thus, the etched bundle is ready to use as a PCF preform. The PCF is observed in the generation of a supercontinuum, with the flat plateau in the spectrum of the output emission stretching from 400 to 1400 nm by experimental measurement. The transmission loss is 0.2-0.3 dB/m at wavelengths of 420-900 nm.

  6. Isotope biogeochemical assessment of natural biodegradation processes in open cast pit mining landscapes

    NASA Astrophysics Data System (ADS)

    Jeschke, Christina; Knöller, Kay; Koschorreck, Matthias; Ussath, Maria; Hoth, Nils

    2014-05-01

    In Germany, a major share of the energy production is based on the burning of lignite from open cast pit mines. The remediation and re-cultivation of the former mining areas in the Lusatian and Central German lignite mining district is an enormous technical and economical challenge. After mine closures, the surrounding landscapes are threatened by acid mine drainage (AMD), i.e. the acidification and mineralization of rising groundwater with metals and inorganic contaminants. The high content of sulfur (sulfuric acid, sulfate), nitrogen (ammonium) and iron compounds (iron-hydroxides) deteriorates the groundwater quality and decelerates sustainable development of tourism in (former) mining landscapes. Natural biodegradation or attenuation (NA) processes of inorganic contaminants are considered to be a technically low impact and an economically beneficial solution. The investigations of the stable isotope compositions of compounds involved in NA processes helps clarify the dynamics of natural degradation and provides specific informations on retention processes of sulfate and nitrogen-compounds in mine dump water, mine dump sediment, and residual pit lakes. In an active mine dump we investigated zones where the process of bacterial sulfate reduction, as one very important NA process, takes place and how NA can be enhanced by injecting reactive substrates. Stable isotopes signatures of sulfur and nitrogen components were examined and evaluated in concert with hydrogeochemical data. In addition, we delineated the sources of ammonium pollution in mine dump sediments and investigated nitrification by 15N-labeling techniques to calculate the limit of the conversion of harmful ammonium to nitrate in residual mining lakes. Ultimately, we provided an isotope biogeochemical assessment of natural attenuation of sulfate and ammonium at mine dump sites and mining lakes. Also, we estimated the risk potential for water in different compartments of the hydrological system. In

  7. The Through Process Simulation of Mold filling, Solidification, and Heat Treatment of the Al Alloy Bending Beam Low-pressure Casting

    NASA Astrophysics Data System (ADS)

    Yin, Yajun; Zhou, Jianxin; Guo, Zhao; Wang, Huan; Liao, Dunming; Chen, Tao

    2015-06-01

    The research on the simulation for the through process of low-pressure casting and heat treatment is conducive to combine information technology and advanced casting technology, which will help to predict the defects and mechanical properties of the castings in the through process. In this paper, we focus on the simulation for through process of low-pressure casting and heat treatment of ZL114A Bending beam. Firstly, we analyzethe distribution of the shrinkage and porosities in filling and solidification process, and simulate the distribution of stress and strain in the late solidification of casting. Then, the numerical simulation of heat treatment process for ZL114A Bending beam is realized according to the heat treatment parameters and the corresponding simulation results of temperature field, stress, strain, and aging performance are given. Finally, we verify that simulation platform for the through process of low-pressure casting and heat treatment can serve the production practice perfectly and provide technical guidance and process optimization for the through process of low-pressure casting and heat treatment.

  8. SLIP CASTING METHOD

    DOEpatents

    Allison, A.G.

    1959-09-01

    S>A process is described for preparing a magnesium oxide slip casting slurry which when used in conjunction with standard casting techniques results in a very strong "green" slip casting and a fired piece of very close dimensional tolerance. The process involves aging an aqueous magnestum oxide slurry, having a basic pH value, until it attains a specified critical viscosity at which time a deflocculating agent is added without upsetting the basic pH value.

  9. Distortion Behavior of a Heavy Hydro Turbine Blade Casting During Forced Air Cooling in Normalizing Treatment Process

    NASA Astrophysics Data System (ADS)

    Yu, Hai-Liang; Kang, Jin-Wu; Wang, Tian-Jiao; Ma, Ji-Yu; Hu, Yong-Yi; Huang, Tian-You; Wang, Shi-Bin; Wu, Ying; Zhang, Cheng-Chun; Dai, Yan-Tao; Li, Peng

    2012-01-01

    Distortion behavior of blade castings in heat treatment process determines their geometrical accuracy, and improper control of it may result in additional repair, shape righting, or even rejection. This article presents a novel approach for discovering the distortion behavior of heavy blade castings during heat treatment process in production. Real-time measurements of distortion and temperature field of a heavy hydro turbine blade casting weighted 17 ton during forced air cooling in normalizing treatment process were carried out by using deformation measurement instruments and an infrared thermal imaging camera. The distortion processes of the typical locations of blade and the temperature field of the blade were obtained. One corner on the blade outlet edge side exhibits variation of distortion with two peaks and a valley. The range reaches 97 mm and the final distortion value is 76 mm. The maximum temperature difference on blade surface reaches 460 °C after 80 min of cooling. Influences of thermal stress and phase transformation stress on the distortion of the blade were elucidated and discussed. The results are of great significance for the understanding and control of the distortion behavior of hydro turbine blades in heat treatment.

  10. CC process optimization through an improved thermal modeling of the cast steel products

    SciTech Connect

    Selaries, J.; Hoffbeck, AM.; Jolivet, JM.; Niederlaender, M.; Perrin, G.; Bobadilla, M.

    1997-12-31

    Heat transfer models developed for continuous casting are more and more becoming simulation tools for defining, from metallurgical criteria, the values of casting parameters (superheat, primary and secondary cooling, casting speed,...) in order to obtain quality products (free from surface cracks and having a low level of central segregation) in the framework of a given production. From this outlook, it is important to have reliable models for the description of the basic mechanisms (heat transfer, microsegregation) as well as for the values relative to the thermophysical data to be used (thermal conductivity, density, enthalpy,...). The studies conducted by IRSID in these fields have made it possible to define the improvements to be brought to the thermal models of continuous casting that are already available. In the first part of this paper, the principles of the improvements brought to the basic models are presented in detail: mathematical formulation taking into account the evolution of the thermal conductivity and the density of steel with temperature, introduction of the microsegregation model adapted to various steel grades (low carbon steels, high carbon steels, stainless steels,...) and selection of the thermophysical data (thermal conductivity, density, enthalpy) with respect to the steel grade. In the second part, some industrial applications of the new model for heat transfers in continuous casting are presented.

  11. Energy Saving Melting and Revert Reduction (E-SMARRT): Precision Casting of Steel

    SciTech Connect

    Dr. Von L. Richards

    2011-09-30

    This project addresses improvements in metal casting processes by reducing scrap and reducing the cost of production, due to scrap reduction from investment casting and yield improvement offered by lost foam casting as compared to no-bake or green sand molding. The objectives for the investment casting portion of the subtask are to improve knowledge of fracture toughness of mold shells and the sources of strength limiting flaws and to understand the effects of wax reclamation procedures on wax properties. Applying 'clean steel' approaches to pouring technology and cleanliness in investment casting of steel are anticipated to improve incoming materials inspection procedures as they affect the microstructure and toughness of the shell. This project focused on two areas of study in the production of steel castings to reduce scrap and save energy: (1) Reducing the amount of shell cracking in investment cast steel production; (2) Investigate the potential of lost foam steel casting The basic findings regarding investment casting shell cracking were: (1) In the case of post pouring cracking, this could be related to phase changes in silica upon cooling and could be delayed by pouring arrangement strategies that maintained the shell surface at temperature for longer time. Employing this delay resulted in less adherent oxidation of castings since the casting was cooler at the time o fair exposure. (2) A model for heat transfer through water saturated shell materials under steam pressure was developed. (3) Initial modeling result of autoclave de-waxing indicated the higher pressure and temperature in the autoclave would impose a steeper temperature gradient on the wax pattern, causing some melt flow prior to bulk expansion and decreasing the stress on the green shell. Basic findings regarding lost foam casting of steel at atmospheric pressure: (1) EPS foam generally decomposes by the collapse mode in steel casting. (2) There is an accumulation of carbon pick-up at the end

  12. Effect of Stress Ratio on the Fatigue Behavior of a Friction Stir Processed Cast Al-Si-Mg Alloy

    SciTech Connect

    Jana, Saumyadeep; Mishra, Rajiv S.; Baumann, John B.; Grant, Glenn J.

    2009-11-01

    The effect of friction stir processing (FSP) on the fatigue life of a cast Al-7Si-0.6Mg alloy at a stress ratio of R=0 was evaluated. Two types of specimen geometry were used for the FSPed condition, through-thickness processed and partial thickness processed. FSP enhanced the fatigue life by a factor of 15 for the through thickness processed samples at lower stress amplitudes. This is different from the FSP specimens tested at R=-1 and similar stress amplitudes where a 5 times improvement in fatigue life was observed. In light of these observations, various closure mechanisms were examined.

  13. Interfacial reaction in cast WC particulate reinforced titanium metal matrix composites coating produced by laser processing

    NASA Astrophysics Data System (ADS)

    Liu, Dejian; Hu, Peipei; Min, Guoqing

    2015-06-01

    Laser injection of ceramic particle was conducted to produce particulate reinforced metal matrix composites (MMCs) coating on Ti-6Al-4V alloy. Cast WC particle (WCp) was used as injection reinforcement to avoid excessive release of carbon atoms into the melt pool. The interfaces and boundaries between WC and Ti matrix were investigated by electron microscopy study. Compared with single crystal WCp, cast WCp was an appropriate solution to control the reaction products (TiC) in the matrix and the total amount of reaction products was significantly reduced. Irregular-shape reaction layers were formed around cast WCp. The reaction layers consist of a W2C layer and a mixed layer of W and TiC. Such reaction layers are effective in load transfer under an external load.

  14. Bifilm Defects in Ni-Based Alloy Castings

    NASA Astrophysics Data System (ADS)

    Campbell, John; Tiryakioğlu, Murat

    2012-08-01

    The Ni-base superalloys, which are normally melted and cast in a vacuum, entrain their surface-oxide film during turbulent pouring of the melt; unfortunately at this time, this process is universally practiced for investment castings of these materials. The entrained film becomes a bifilm crack automatically, so that cast alloys have a large population of cracks that controls their failure behavior. The problems of the growth of single crystals and the welding of polycrystalline alloys are reviewed to illustrate the central role of bifilms in the cracking of turbine blades, the heat-affected zones of welds, and the reliability of properties. It has been demonstrated that improved gravity pouring systems can reduce these problems significantly, but only countergravity filling of molds is expected to result in defect-free castings. Recent cases in which turbine blades failed in service are examined, and the central role of bifilm defects in these failures is discussed.

  15. Development of a CFD code for casting simulation

    NASA Technical Reports Server (NTRS)

    Murph, Jesse E.

    1993-01-01

    Because of high rejection rates for large structural castings (e.g., the Space Shuttle Main Engine Alternate Turbopump Design Program), a reliable casting simulation computer code is very desirable. This code would reduce both the development time and life cycle costs by allowing accurate modeling of the entire casting process. While this code could be used for other types of castings, the most significant reductions of time and cost would probably be realized in complex investment castings, where any reduction in the number of development castings would be of significant benefit. The casting process is conveniently divided into three distinct phases: (1) mold filling, where the melt is poured or forced into the mold cavity; (2) solidification, where the melt undergoes a phase change to the solid state; and (3) cool down, where the solidified part continues to cool to ambient conditions. While these phases may appear to be separate and distinct, temporal overlaps do exist between phases (e.g., local solidification occurring during mold filling), and some phenomenological events are affected by others (e.g., residual stresses depend on solidification and cooling rates). Therefore, a reliable code must accurately model all three phases and the interactions between each. While many codes have been developed (to various stages of complexity) to model the solidification and cool down phases, only a few codes have been developed to model mold filling.

  16. Influence of the fabrication process on the functionality of piezoceramic patch transducers embedded in aluminum die castings

    NASA Astrophysics Data System (ADS)

    Klassen, Alexander; Rübner, Matthias; Ilg, Jürgen; Rupitsch, Stefan J.; Lerch, Reinhard; Singer, Robert F.; Körner, Carolin

    2012-11-01

    Piezoceramic patch transducers are integrated into aluminum components using high-pressure die casting. Expanded metal has proven suitable as a supporting structure for placing the patch transducers inside the die cavity and for stabilization during the injection of molten metal. However, difficulties arise when the transducers are positioned off the neutral axis within the wall of the casting. Numerical simulations of the die filling are performed to analyse the evolution of the integration process. The asymmetric infiltration of the supporting structure is identified as the major factor contributing to the formation of cracks and perforations inside the piezoceramic transducer. By means of measurements and numerical calculations of the electrical impedance of the transducer, a close relation is established between mechanical damage patterns observed in radiographs of the patch transducers and loss of performance.

  17. Semi-solid Twin-roll Casting Process of Magnesium Alloy Sheets

    NASA Astrophysics Data System (ADS)

    Watari, H.; Davey, K.; Rasgado, M. T. Alonso; Haga, T.; Koga, N.

    2004-06-01

    An experimental approach has been performed to ascertain the effectiveness of semi-solid strip casting using a horizontal twin roll caster. The demand for light-weight products with high strength has grown recently due to the rapid development of automobile and aircraft technology. One key to such development has been utilization of magnesium alloys, which can potentially reduce the total product weight. However, the problems of utilizing magnesium alloys are still mainly related to high manufacturing cost. One of the solutions to this problem is to develop magnesium casting-rolling technology in order to produce magnesium sheet products at competitive cost for commercial applications. In this experiment, magnesium alloy AZ31B was used to ascertain the effectiveness of semi-solid roll strip casting for producing magnesium alloy sheets. The temperature of the molten magnesium, and the roll speeds of the upper and lower rolls, (which could be changed independently), were varied to find an appropriate manufacturing condition. Rolling and heat treatment conditions were changed to examine which condition would be appropriate for producing wrought magnesium alloys with good formability. Microscopic observation of the crystals of the manufactured wrought magnesium alloys was performed. It has been found that a limiting drawing ratio of 2.7 was possible in a warm deep drawing test of the cast magnesium alloy sheets after being hot rolled.

  18. Processing and Characterization of Functionally Graded Aluminum (A319)—SiCp Metallic Composites by Centrifugal Casting Technique

    NASA Astrophysics Data System (ADS)

    Jayakumar, E.; Jacob, Jibin C.; Rajan, T. P. D.; Joseph, M. A.; Pai, B. C.

    2016-06-01

    Functionally graded materials (FGM) are successfully adopted for the design and fabrication of engineering components with location-specific properties. The present study describes the processing and characterization of A319 Aluminum functionally graded metal matrix composites (FGMMC) with 10 and 15 wt pct SiCp reinforcements. The liquid stir casting method is used for composite melt preparation followed by FGMMC formation by vertical centrifugal casting method. The process parameters used are the mold preheating temperature of 523 K (250 °C), melt pouring temperature of 1013 K (740 °C), and mold rotation speed of 1300 rpm. The study analyzes the distribution and concentration of reinforcement particles in the radial direction of the FGMMC disk along with the effects of gradation on density, hardness, mechanical strength, the variation in coefficient of thermal expansion and the wear resistance properties at different zones. Microstructures of FGMMC reveal an outward radial gradient distribution of reinforcements forming different zones. Namely, matrix-rich inner, transition, particles-rich outer, and chill zone of a few millimeters thick at the outer most periphery of the casting are formed. From 10-FGM, a radial shift in the position of SiCp maxima is observed in 15-FGM casting. The mechanical characterization depicts enhanced properties for the particle-rich zone. The hardness shows a graded nature in correlation with particle concentration and a maximum of 94.4 HRB has been obtained at the particle-rich region of 15-FGM. In the particle-rich zone, the lowest CTE value of 20.1 µm/mK is also observed with a compressive strength of 650 MPa and an ultimate tensile strength of 279 MPa. The wear resistance is higher at the particle-rich zone of the FGMMC.

  19. Processing and Characterization of Functionally Graded Aluminum (A319)—SiCp Metallic Composites by Centrifugal Casting Technique

    NASA Astrophysics Data System (ADS)

    Jayakumar, E.; Jacob, Jibin C.; Rajan, T. P. D.; Joseph, M. A.; Pai, B. C.

    2016-08-01

    Functionally graded materials (FGM) are successfully adopted for the design and fabrication of engineering components with location-specific properties. The present study describes the processing and characterization of A319 Aluminum functionally graded metal matrix composites (FGMMC) with 10 and 15 wt pct SiCp reinforcements. The liquid stir casting method is used for composite melt preparation followed by FGMMC formation by vertical centrifugal casting method. The process parameters used are the mold preheating temperature of 523 K (250 °C), melt pouring temperature of 1013 K (740 °C), and mold rotation speed of 1300 rpm. The study analyzes the distribution and concentration of reinforcement particles in the radial direction of the FGMMC disk along with the effects of gradation on density, hardness, mechanical strength, the variation in coefficient of thermal expansion and the wear resistance properties at different zones. Microstructures of FGMMC reveal an outward radial gradient distribution of reinforcements forming different zones. Namely, matrix-rich inner, transition, particles-rich outer, and chill zone of a few millimeters thick at the outer most periphery of the casting are formed. From 10-FGM, a radial shift in the position of SiCp maxima is observed in 15-FGM casting. The mechanical characterization depicts enhanced properties for the particle-rich zone. The hardness shows a graded nature in correlation with particle concentration and a maximum of 94.4 HRB has been obtained at the particle-rich region of 15-FGM. In the particle-rich zone, the lowest CTE value of 20.1 µm/mK is also observed with a compressive strength of 650 MPa and an ultimate tensile strength of 279 MPa. The wear resistance is higher at the particle-rich zone of the FGMMC.

  20. A Neuroeconomics Analysis of Investment Process with Money Flow Information: The Error-Related Negativity

    PubMed Central

    Wang, Cuicui; Vieito, João Paulo; Ma, Qingguo

    2015-01-01

    This investigation is among the first ones to analyze the neural basis of an investment process with money flow information of financial market, using a simplified task where volunteers had to choose to buy or not to buy stocks based on the display of positive or negative money flow information. After choosing “to buy” or “not to buy,” participants were presented with feedback. At the same time, event-related potentials (ERPs) were used to record investor's brain activity and capture the event-related negativity (ERN) and feedback-related negativity (FRN) components. The results of ERN suggested that there might be a higher risk and more conflict when buying stocks with negative net money flow information than positive net money flow information, and the inverse was also true for the “not to buy” stocks option. The FRN component evoked by the bad outcome of a decision was more negative than that by the good outcome, which reflected the difference between the values of the actual and expected outcome. From the research, we could further understand how investors perceived money flow information of financial market and the neural cognitive effect in investment process. PMID:26557139

  1. A Neuroeconomics Analysis of Investment Process with Money Flow Information: The Error-Related Negativity.

    PubMed

    Wang, Cuicui; Vieito, João Paulo; Ma, Qingguo

    2015-01-01

    This investigation is among the first ones to analyze the neural basis of an investment process with money flow information of financial market, using a simplified task where volunteers had to choose to buy or not to buy stocks based on the display of positive or negative money flow information. After choosing "to buy" or "not to buy," participants were presented with feedback. At the same time, event-related potentials (ERPs) were used to record investor's brain activity and capture the event-related negativity (ERN) and feedback-related negativity (FRN) components. The results of ERN suggested that there might be a higher risk and more conflict when buying stocks with negative net money flow information than positive net money flow information, and the inverse was also true for the "not to buy" stocks option. The FRN component evoked by the bad outcome of a decision was more negative than that by the good outcome, which reflected the difference between the values of the actual and expected outcome. From the research, we could further understand how investors perceived money flow information of financial market and the neural cognitive effect in investment process. PMID:26557139

  2. Energy Saving Melting and Revert Reduction Technology: Improved Die Casting Process to Preserve the Life of the Inserts

    SciTech Connect

    David Schwam, PI; Xuejun Zhu, Sr. Research Associate

    2012-09-30

    The goal of this project was to study the combined effects of die design, proper internal cooling and efficient die lubricants on die life. The project targeted improvements in die casting insert life by: Optomized Die Design for Reduced Surface Temperature: The life of die casting dies is significantly shorter when the die is exposed to elevated temperature for significant periods of time. Any die operated under conditions leading to surface temperature in excess of 1050oF undergoes structural changes that reduce its strength. Optimized die design can improve die life significantly. This improvement can be accomplished by means of cooling lines, baffles and bubblers in the die. A key objective of the project was to establish criteria for the minimal distance of the cooling lines from the surface. This effort was supported with alloys and machining by BohlerUddeholm, Dunn Steel, HH Stark and Rex Buckeye. In plant testing and evaluation was conducted as in-kind cost share at St. Clair Die Casting. The Uddeholm Dievar steel evaluated in this program showed superior resistance to thermal fatigue resistance. Based on the experimental evidence, cooling lines could be placed as close as 0.5" from the surface. Die Life Extension by Optimized Die Lubrication: The life of die casting dies is affected by additions made to its surface with the proper lubricants. These lubricants will protect the surface from the considerable temperature peaks that occur when the molten melt enters the die. Dies will reach a significantly higher temperature without this lubricant being applied. The amount and type of the lubricant are critical variables in the die casting process. However, these lubricants must not corrode the die surface. This effort was supported with alloys and machining by BohlerUddeholm, Dunn Steel, HH Stark and Rex Buckeye. In plant testing and evaluation was conducted as in-kind cost share at St. Clair Die Casting. Chem- Trend participated in the program with die

  3. Effect of TurboSwirl Structure on an Uphill Teeming Ingot Casting Process

    NASA Astrophysics Data System (ADS)

    Bai, Haitong; Ersson, Mikael; Jönsson, Pär

    2015-12-01

    To produce high-quality ingot cast steel with a better surface quality, it would be beneficial for the uphill teeming process if a much more stable flow pattern could be achieved in the runners. Several techniques have been utilized in the industry to try to obtain a stable flow of liquid steel, such as a swirling flow. Some research has indicated that a swirl blade inserted in the horizontal and vertical runners, or some other additional devices and physics could generate a swirling flow in order to give a lower hump height, avoid mold flux entrapment, and improve the quality of the ingot products, and a new swirling flow generation component, TurboSwirl, was introduced to improve the flow pattern. It has recently been demonstrated that the TurboSwirl method can effectively reduce the risk of mold flux entrapment, lower the maximum wall shear stress, and decrease velocity fluctuations. The TurboSwirl is built at the elbow of the runners as a connection between the horizontal and vertical runners. It is located near the mold and it generates a tangential flow that can be used with a divergent nozzle in order to decrease the axial velocity of the vertical flow into the mold. This stabilizes flow before the fluid enters the mold. However, high wall shear stresses develop at the walls due to the fierce rotation in the TurboSwirl. In order to achieve a calmer flow and to protect the refractory wall, some structural improvements have been made. It was found that by changing the flaring angle of the divergent nozzle, it was possible to lower the axial velocity and wall shear stress. Moreover, when the vertical runner and the divergent nozzle were not placed at the center of the TurboSwirl, quite different flow patterns could be obtained to meet to different requirements. In addition, the swirl numbers of all the cases mentioned above were calculated to ensure that the swirling flow was strong enough to generate a swirling flow of the liquid steel in the TurboSwirl.

  4. Anisotropic Responses of Mechanical and Thermal Processed Cast Al-Si-Mg-Cu Alloy

    NASA Astrophysics Data System (ADS)

    Adeosun, S. O.; Akpan, E. I.; Balogun, S. A.; Onoyemi, O. K.

    2015-05-01

    The effects of ambient directional rolling and heat treatments on ultimate tensile strength (UTS), hardness (HD), percent elongation (PE), and impact energy (IE) on Al-Si-Mg-Cu alloy casting with reference to inclination to rolling direction are discussed in this article. The results show that rolled and quenched (CQ) sample possess superior UTS and HD to as-cast and those of rolled and aged samples (CA). Improved IE resistance with ductility is shown by both CQ and CA samples. However, these mechanical properties are enhanced as changes in the test sample direction moved away from rolling direction for all heat-treated samples. The CQ samples displayed highest tensile strength (108 MPa) and PE (19.8%) in the 90° direction.

  5. Casting materials

    DOEpatents

    Chaudhry, Anil R.; Dzugan, Robert; Harrington, Richard M.; Neece, Faurice D.; Singh, Nipendra P.

    2011-06-14

    A foam material comprises a liquid polymer and a liquid isocyanate which is mixed to make a solution that is poured, injected or otherwise deposited into a corresponding mold. A reaction from the mixture of the liquid polymer and liquid isocyanate inside the mold forms a thermally collapsible foam structure having a shape that corresponds to the inside surface configuration of the mold and a skin that is continuous and unbroken. Once the reaction is complete, the foam pattern is removed from the mold and may be used as a pattern in any number of conventional casting processes.

  6. Processing, Microstructure and Mechanical Behavior of Ultrasonic Assisted Cast Magnesium 1wt% Silicon Carbide Nano-Composites

    NASA Astrophysics Data System (ADS)

    Erman, Ari

    The goal of this dissertation is to establish an understanding of processing -- microstructure -- mechanical behavior relationship in Mg-1wt% SiC metal matrix nano-composites fabricated via an ultrasonic assisted casting process, with the emphasis on the effect of the distribution of nanoparticles on this relationship. Ultrasonic assisted casting has been proved as an effective technique to distribute nanoparticles in Mg metal matrix nano-composites (MMNCs). Mg MMNCs reinforced with 1 wt% SiC nanoparticles, were cast by ultrasonic cavitation-based dispersion methods. Microstructural analyses of as cast specimens were conducted to characterize the grain size, shape and distribution, SiC nanoparticle size and distribution, and nanoparticle-matrix interface. Average grain size for the ultrasonic assisted cast composite specimens was 72 mum compared to 181 mum for pure Mg samples prepared by the same method. The average measured SiC nanoparticle size was 66 nm. TEM studies showed good local dispersion of SiC nanoparticles, with only a few small, widely spaced clusters. HRTEM showed a clean interface between SiC nanoparticles and the Mg matrix, with no evidence of secondary phases. The yield strength of Mg-1 wt% SiC nanocomposites was 67 MPa, which showed improvement from 47 MPa for the pure Mg samples. This extra strengthening is due to Orowan and Hall-Petch effects. Fatigue experiments were conducted to characterize the cyclic stress-strain response of pure Mg and Mg-1wt% SiC samples at 0.2%, 0.4% and 0.6% plastic strain amplitudes. The analyses of the cyclic stress response curves and hysteresis loops, combined with post failure TEM analyses provided an understanding of the role of twinning, and twin-particle interactions on the cyclic deformation behavior of Mg MMNCs. Tensile twinning and basal slip are the main forms of deformation mechanisms under compression, followed by detwinning and basal slip in subsequent tension. Fatigue lives of Mg MMNCs are comparable to

  7. Nonintrusive sensing and control for intelligent processing and design of castings

    SciTech Connect

    Kunerth, D.C.; Gray, J.

    1995-11-01

    Two technologies, laser ultrasonics (LUT) for detecting inclusions in liquid metals and x-ray stereography (XS) for detecting and locating porosity and inclusions in castings, were evaluated. LUT is a relatively new technology that has the potential to operate in the harsh environment of metal melting, without melt contamination, because of its noncontacting nature. It was shown that LUT can detect and monitor inclusions in liquid metal, but limitations exist that restrict its implementation as well as minimize the advantage gained from its noncontacting nature. In many applications it is acceptable for castings to have a limited amount of inclusions or porosity if these are not in a critical location. XS can determine the physical location of defects and, when integrated into a real-time radiographic system, is useful for quickly evaluating the quality of castings prior to adding value via finish steps. It was demonstrated that XS can achieve a location accuracy of 0.2 mm relative to a part surface and can be configured as an inexpensive add-on to existing real-time systems.

  8. Interplay Between Residual Stresses, Microstructure, Process Variables and Engine Block Casting Integrity

    NASA Astrophysics Data System (ADS)

    Lombardi, Anthony; D'Elia, Francesco; Ravindran, Comondore; Sediako, Dimitry; Murty, B. S.; MacKay, Robert

    2012-12-01

    The replacement of nodular cast iron with 319 type aluminum (Al) alloys in gasoline engine blocks is an example of the shift towards the use of lighter alloys in the automotive industry. However, excessive residual stress along the cylinder bore may lead to bore distortion, significantly reducing engine operating efficiency. In the current study, microstructure, mechanical properties and residual stress were characterized along the cylinder bridge of engine blocks following thermal sand reclamation (TSR), T7 heat treatment, and service testing of the casting. Neutron diffraction was effectively used to quantify the residual stress along both the Al cylinder bridge and the adjacent gray cast iron cylinder liners in the hoop, radial, and axial orientations with respect to the cylinder axis. The results suggest that an increase in cooling rate along the cylinder caused a significant refinement in microstructure at the bottom of the cylinder. In turn, this suggested an increase in alloy strength at the bottom of the cylinder relative to the top. This increased strength at the bottom of the cylinder likely reduced the susceptibility of the cylinder to rapid relief of residual stress at elevated temperature. In contrast, the coarse microstructure at the top of the cylinder likely triggered stress relief at an elevated temperature.

  9. Assessment of Computer Simulation Software and Process Data for High Pressure Die Casting of Magnesium

    SciTech Connect

    Sabau, Adrian S; Hatfield, Edward C; Dinwiddie, Ralph Barton; Kuwana, Kazunori; Viti, Valerio; Hassan, Mohamed I; Saito, Kozo

    2007-09-01

    Computer software for the numerical simulation of solidification and mold filling is an effective design tool for cast structural automotive magnesium components. A review of commercial software capabilities and their validation procedures was conducted. Aside form the software assessment, the program addressed five main areas: lubricant degradation, lubricant application, gate atomization, and heat transfer at metal mold interfaces. A test stand for lubricant application was designed. A sensor was used for the direct measurement of heat fluxes during lubricant application and casting solidification in graphite molds. Spray experiments were conducted using pure deionized water and commercial die lubricants. The results show that the sensor can be used with confidence for measuring heat fluxes under conditions specific to the die lube application. The data on heat flux was presented in forms suitable for use in HPDC simulation software. Severe jet breakup and atomization phenomena are likely to occur due to high gate velocities in HPDC. As a result of gate atomization, droplet flow affects the mold filling pattern, air entrapment, skin formation, and ensuing defects. Warm water analogue dies were designed for obtaining experimental data on mold filling phenomena. Data on break-up jet length, break-up pattern, velocities, and droplet size distribution were obtained experimentally and was used to develop correlations for jet break-up phenomena specific to die casting gate configurations.

  10. Material Characterization of Austempered Ductile Iron (ADI) Produced by a Sustainable Continuous Casting-Heat Treatment Process

    NASA Astrophysics Data System (ADS)

    Meena, Anil; El Mansori, Mohamed

    2012-12-01

    Selecting a suitable manufacturing process is one way of achieving sustainability of a product by diminishing energy consumption during its production cycle and improving material efficiency. The article attempts to explore the new processing technology for direct manufacturing of lightweight austempered ductile iron (ADI) casting in a permanent mold. The new processing technology is based on the innovative integrated approach toward casting and heat-treatment process. In this technology, the ductile iron samples obtained using the permanent mold are first austenized immediately after solidification process followed by austempering heat treatment in the fluidized bed and then air cooled at room temperature to obtain ADI material. The influence of austempering time on the microstructural characteristics, mechanical properties, and strain-hardening behavior of ADI was studied. Optical microscopy, scanning electron microscopy (SEM), and X-ray diffraction (XRD) analyses were performed to correlate the mechanical properties with microstructural characteristics. It was observed that the mechanical properties of resulting ADI samples were influenced by the microstructural transformations and varied retained austenite volume fractions obtained due to different austempering time. The results indicate that the strain-hardening behavior of the ADI material is influenced by the carbon content of retained austenite.