February 2022 Volume 4

FORGING RESEARCH

The angular deviation from the initial Burgers Orientation Relationship (BOR) is shown with overlaid experimental data from Semiatin et al . in Figure 4. The gray regions are orientations which were reported to be slow to globularize. [2]. As illustrated, the simulation results are strongly consistent with the reported experimental results. However, the simulation results suggest that the single set of experimental analysis may not capture the full extent of orientation dependence. In the original experimental results, orientation dependence is reported solely based on the tilt of of the

phase c-axis relative to the compression direction. The simulation results suggest a secondary effect where the rotation about the c-axis is also important. There is one notable region where the simulation results are inconsistent with the Bieler and Semiatin's experimental data: in compression along the c-axis. In experiments, these orientations are reported to kink rather than plastically deforming; this phenomenology is not captured in the VPSC model. This model shortcoming is addressed below.

Figure 4: Angular deviation from initial BOR overlaid with experimental observations from Reference [2]. The simulation results are strongly consistent with experimental results, but also suggest that there is likely more nuance to the orientation-dependence of globularization than originally reported. Figure 4: Angular deviation from initial BOR overlaid with experimental observations from Reference [2]. The simulation results are strongly consistent with experimental results, but also suggest that there is likely more nuance to the orientation-dependence of globularization than originally reported.

5. Unsurprisingly, the stable vs. unstable orientations change substantially with different loading types. However, the primary takeaway is that far fewer orientations are stable in plane strain compression or simple shear than in uniaxial loading; more complex loading conditions will tend to have fewer issues with unperturbed colonies.

1.2 Newmonotonic loading scenarios Under this award, many additional loading scenarios, assumptions for constitutive behavior, and boundary conditions were simulated. First, different simple monotonic strain paths were examined: plane strain compression (idealized rolling) and simple shear. The deviations from BOR after deformation are shown in Figure Figure 4: Angular deviation from initial BOR overlaid with experimental ob erva ions from Reference [2]. The simulation results are strongly consistent with experimental resul s, but also suggest that there is likely more nuance to the orientation-dependence of globularization than originally reported.

Figure 5: Deviation from the initial BOR as a function of colony loading direction for different monotonic loading scenarios.

1.2 New monotonic loading scenarios

FIA MAGAZINE | FEBRUARY 2022 80 Next, different constitutive behavior was examined by changing the relative critical resolved shear stresses (CRSSs) for slip. In the original work, the CRSS values were taken directly from Reference [3] and perfectly plastic deformation was assumed. Also, each a direction was assumed to behave differently due to the initial BOR and the anisotropy of Under this award, many additional loading scenarios, assumptions for constitutive behavior, and boundary conditions were simulated. First, different simple monotonic strain paths were examined: plane strain compression (idealized rolling) and simple shear. The deviations from BOR after deformation are shown Under this award, many additional loading scenarios, assumptions for constitutive behavior, and boundary conditions were simulated. First, different simple monotonic strain paths were examined: plane strain compression (idealized rolling) and simple shear. The deviations from BOR after deformation are shown in Figure 5. Unsurprisingly, the stable vs. unstable orientations change substantially with different loading types. However, the primary takeaway is that far fewer orientations are stable in plane strain compression or simple shear than in uniaxial loading; more complex loading conditions will tend to have fewer issues with unperturbed colonies. Figure 5: Deviation from the initial BOR as a function of colony loading direction for different monotonic loading scenarios. 1.2 New monotonic loadi g scenarios Figure 5: Dev ation from the initial BOR s a function of colony loading direction for different monotonic loading sc narios.