Cast Shop Technology: Metal Treatment and Shape Casting
Sponsored by: TMS Light Metals Division, TMS: Aluminum Committee
Program Organizers: Samuel Wagstaff, Oculatus Consulting
Wednesday 2:00 PM
March 17, 2021
Room: RM 29
Location: TMS2021 Virtual
Session Chair: Filippos Patsiogiannis, Bridgnorth Aluminium
2:00 PM
Grain Refinement Efficiency: Rein Vainik1; John Courtenay1; Frode Lien1; 1MQP Ltd
New results on grain refinement of aluminium are presented by using the efficiency concept, which is a powerful tool to compare the nucleation efficiency of different grain refiners. This involves calculation of nucleation sites per unit volume, which gives much more information about nucleation than intercept grain size. The different methods of measuring efficiency are discussed. Optifine, a high efficiency grain refiner, has been on the market for almost 10 years. When Optifine is implemented at cast houses, the grain refiner additions can be minimised, using the growth restriction effect that titanium in liquid solution imposes on the first nucleated aluminium crystals. The efficiency concept is utilised in our grain refinement test method to accurately calibrate the performance of each batch of Optifine. Decreased grain refiner additions are beneficial for many reasons, e.g. lower cost, less impurities leading to less defects, enhanced surface quality, less blocking of filters etc.
2:20 PM
A Comparison of AA6060 Grain Structures Achieved Using AMG’s TiBAl Advance™ and Alternative Al-Ti-B Grain Refiners via a 1D Upward Solidification Device: Matthew Piper1; Shahid Akhtar2; Phil Enright3; 1AMG Aluminum UK Limited; 2Hydro Aluminium Reseach Centre; 3NTec
Using a 1D upward solidification device with indirect to direct chill transition, the as-cast grain structures of an AA6060 alloy were evaluated for different Al-Ti-B grain refiner types and addition rates. Through consideration of the individual and combined effects of heterogeneous nucleation and grain growth restriction, a method is provided to reduce the grain refiner addition rate by at least 50 %, whilst maintaining the desired grain structure. Scanning electron microscopy (SEM) characterisation was carried out on the microstructures of each grain refiner, and the size distributions of TiB2 particles were compared. The grain refining efficiency of AMG’s TiBAl Advance is demonstrated to surpass that of other grain refiners tested. TiBAl Advance is suggested to introduce a greater number density of nucleation sites on which free growth of α – Al could be expected to prevail. However, supplementary work is necessary to explain the exact mechanism.
2:40 PM
Mechanism of High Grain Refinement Effectiveness on New Grain Refiner “TiBAl Advance”: Akihiro Minagawa1; Matthew Piper2; 1Uacj Corporation; 2AMG Aluminum
Grain refiners are used for the aluminum DC casting process to easily refine the cast structure. On the other hand, high levels of TiB2 particles and other inclusions in the grain refiner cause clogging of the melt filter. Improvement of the grain refinement effectiveness is required to reduce the addition level of grain refiners. The grain refiner supplier AMG developed “TiBAl Advance”, which is high performance Al-3Ti-1B (mass%) grain refiner. TiBAl Advance is a selected grain refiner that has passed a special casting test. However, the reason why high grain refinement effectiveness is not clarified yet. In this work, the grain refinement effectiveness of TiBAl Advance was compared with conventional grain refiner. In addition, TiB2 particle size distributions, including agglomerates, were measured in each refiner, and applied to the new model for the grain size prediction to estimate the mechanism of the difference of grain refinement effectiveness.
3:00 PM
Resonance for Contactless Ultrasonic Treatment in Direct Chill Casting: Catherine Tonry1; Valdis Bojarevics1; Georgi Djambazov1; Koulis Pericleous1; 1Unviersity of Greenwich
Grain refinement is desirable in direct chill (DC) casting. Ultrasonic treatment (UST) has been proven to be a grain refinement technique. Immersed sonotrodes have been employed for this purpose to treat alloys both within the launder or directly in the sump. We propose an alternative electromagnetic (EM) technique used directly in the caster. This ‘contactless sonotrode’ technique uses a kilohertz frequency induction coil tuned to reach acoustic resonance within the melt pool. The technique has been successfully used in batch to refine the microstructure and degas aluminum in a crucible. We extend numerical models, coupling electromagnetics, fluid flow, gas cavitation, heat transfer and solidification to examine use in the DC process. Simulations show that a consistent resonant mode is obtainable within a vigorously mixed melt pool, with pressures high enough to achieve cavitation. It is expected conditions in the mushy zone due to cavitation would promote dendrite fragmentation.
3:20 PM
Ultrasonic Melt Treatment in a DC Casting Launder: The Role of Melt Processing Temperature: Christopher Beckwith1; Tungky Subroto2; Koulis Pericleous1; Georgi Djambazov1; Dmitry Eskin2; Iakovos Tzanakis3; 1University of Greenwich; 2Brunel University London; 3Oxford Brookes University
Ultrasonic melt treatment (UST) using a single sonotrode source in a launder is an efficient way to treat a large-volume melt. One key parameter is the temperature of the melt. Melt temperature affects the acoustic pressure generated by the sonotrode, which ultimately defines the cavitation development as well as the resulting acoustic streaming. Experiments have also shown that temperature affects the final grain size, as well as the intermetallic size and number density. This work presents a numerical model covering acoustic cavitation, flow (including acoustic streaming) and heat transfer in direct-chill (DC) casting, to better understand this process. The UST effectiveness is quantified through the size of the high-pressure acoustic region and the melt residence time and is validated against experimental data. The output of this work is useful for optimizing the selection of process parameters for UST DC casting.
3:40 PM
Residual Stress Prediction in the Casting Process of Automotive Powertrain Components: Sina Kianfar1; Joshua Stroh1; Nasim Bahramian1; Dimitry G. Sediako1; Anthony Lombardi2; Glenn Byczynski2; Philipp Mayr3; Mark Reid4; Anna Paradowska4; 1University of British Columbia; 2Nemak Canada; 3Nemak Global; 4ANSTO
Residual stress development during the manufacturing process of powertrain components, such as engine blocks, is a primary source of premature failure. Residual stress may induce in-service dimensional instability and crack formations, which poses challenges for developing high-efficiency engines. Hence, adopting a reliable approach for accurate prediction and characterization of residual stresses plays a vital role in efficient stress management. Advanced numerical techniques using versatile finite element methods are viable tools for stress analyses. The current study develops a numerical model of the residual stress evolution in engine blocks during the casting procedure. To determine the proper modelling and process parameters, the simulation was initially conducted on a simplified standard geometry. Then, the casting process of an I6 bore-chilled sand-cast engine block was simulated in ANSYSTM. The results revealed that there was a positive correlation between the predicted residual stresses and neutron diffraction data, specifically in the engine block’s axial orientation.
4:00 PM
Coupled Modeling of Misrun, Could Shut, Air Entrainment and Porosity for High Pressure Die Casting Applications: Juergen Jakumeit1; Herfried Behnken1; Romuald Laqua1; Simon Mbewou2; Martin Fehlbier2; Julian Gänz3; Leonard Becker3; 1Access E.V.; 2Foundry technic, University Kassel; 3Siemens Industry Software GmbH, DI SW STS CCM TO
High pressure casting (HPDC) is an increasingly important production process for large, thin-walled components. When geometries combine large thin areas with volumetric regions, defects due to misruns, cold shuts, air pockets and porosity can occur in close proximity and influence each other. Simulation-based process optimization requires a combined modeling approach to capture these errors fully coupled.To address this task a multi-phase fully coupled mold filling and solidification methodology has been developed. Liquid melt and gas are treated as compressible fluids separated by a sharp volume of fluid interface. Reduced melt flow due to solidification is achieved by a mushy-zone model. The methodology allows the simultaneous simulation of reduced melt flow, air compression and porosity formation due to gas evaporation and volume shrinkage. The ability to address these defects with one combined modelling approach was validated by casting trials using a specially designed geometry for thin-walled aluminum HPDC applications.
4:20 PM
Study on the Mechanical Properties of Commercial Vehicle Wheel Through the Molten-Forged on the A356 Alloy with a Multi-cavity Fabrication Process: Min Seok Moon1; Myeong Han Yoo1; Kee Won Kim2; Joon Hyuk Song1; Je Ha Oh1; 1Korea Institute of Carbon Convergence Technology; 2Rheoforge Co., Ltd.
This study is related to lightweight automobiles due to global warming, with the reduction of fossil fuel reserves are rapidly progressing around the automobile industry. This study has revealed the relationship for the mechanical properties via the analyzed microstructure, precipitated phase variation of the wheel hub of a commercial vehicle manufactured using molten forging technology using A356 alloy, which is high-strength Al-Si base cast aluminum alloys. DSC(Differential scanning calorimetry) analysis has performed to analyze the precipitation amount of material that influences the mechanical properties of aluminum alloy. The XRD analysis has measured for the microstructure's crystal phase on the A356 alloy. In this paper has evaluated to compare the properties of the A356 alloy for the mechanical properties. Therefore, this study confirmed that the A356 alloy has excellent mechanical properties by microstructure and thermal analysis.
4:40 PM Question and Answer Period