February 2022 Volume 4

FORGING RESEARCH

in the specimen coordinate system. New code infrastructure was developed to incorporate all of these complications. As shown in Figure 8, the point track file from the DEFORM software package is used as a starting point. A VPSC-based post-processing routine is then run using the point track file as an input. With this code infrastructure, site specific texture evolution (and therefore microtexture evolution and globularization behavior) can be calculated within a given component.

1.3 Realistic thermomechanical processing scenarios While the simple loading scenarios above are insightful for testing which physics must be incorporated into this simulation methodology, they are ultimately not realistic thermomechanical processing scenarios in comparison to those used in industry today. Real processing paths are non-isothermal, contain variable deformation rates, and contain many steps including re-orientations

Figure 8: DEFORM-generated point track files are post-processed using developed codes. VPSC is run at each DEFORM step and at each point, with the phase fractions and CRSS values updated as the temperature changes. From these simulations, site-specific evolution can be predicted. Figure 8: DEFORM-generated point track files are post-processed using developed codes. VPSC is run at each DEFORM step and at each point, with the phase fractions and CRSS values updated as the temperature changes. From these simulations, site-specific evolution can be predicted.

Starting from the DEFORM outputs, the temperatures are used to calcuate phase fractions of the and β phases using either equilibrium phase fractions or phase fractions based on continuous cooling transformation data. The temperature is also used to appropriately scale the CRSS values of each phase. The velocity gradients at each point are used to write deformation pathways for VPSC. Using these inputs, VPSC is run iteratively at each

orientations.” In a polycrystal, these orientations would undergo relatively little strain relative to their softer neighbors. To capture this effect, stress-controlled trials were run in uniaxial compression. It is assumed that stress control will help to represent load-shedding and possibly the kinking behavior that the original simulations missed. The stress-controlled simulation results are presented in Figure 7. As illustrated, now loading directions aligned with the α c axis are correctly predicted to be difficult to globularize. Incorporating more elements of stress-controlled deformation also appears to be a promising strategy for improving simulation predictive power. 1.3 Realistic thermomechanical processing scenarios While the simple loading scenarios above are insightful for testing which physics must be incorporated into this simulation methodology, they are ultimately not realistic ther- momechanical processing scenarios in comparison to those used in industry today. Real processing paths are non-isothermal, contain variable deformation rates, and contain many steps including re-orientations in the specimen coordinate system. New code infrastruc- ture was developed to incorporate all of these complications. As shown in Figure 8, the point track file from the DEFORM software package is used as a starting point. A VPSC- based post-processing routine is then run using the point track file as an input. With this code infrastructure, site specific texture evolution (and therefore microtexture evolution and globularization behavior) can be calculated within a given component. Starting from the DEFORM outputs, the temperatures are used to calcuate phase frac- tions of the α and β phases using either equilibrium phase fractions or phase fractions based on continuous cooling transformation data. The temperature is also used to appro- priately scale the CRSS values of each phase. The velocity gradients at each point are used to write deformation pathways for VPSC. Using these inputs, VPSC is run iteratively at each DEFORM timestep for each point. When the workpiece is rotated in DEFORM, the grain orientations in VPSC are correspondingly rotated. The output textures in VPSC are also rotated back into the original reference frame for ease of interpretation. The flow of information through the code is illustrated schematically in Figure 9. DEFORM timestep for each point. When the workpiece is rotated in DEFORM, the grain orientations in VPSC are correspondingly rotated. The output textures in VPSC are also rotated back into the original reference frame for ease of interpretation. The flow of information through the code is illustrated schematically in Figure 9. Figure 9: Schematic of the flow of information through the VPSC-DEFORM framework. Figure 9: Schematic of the flow of information through the VPSC-DEFORM framework.

FIA MAGAZINE | FEBRUARY 2022 82 shots of the three tabs of the GUI are shown in Figure 10. This framework is still in active development and will be the subject of several forth- coming presentation. It has been developed in a modular way, so that new materials physics