Positive Strain Rate Sensitivity and Deformation Behavior of a Fe-29Mn-3Al-3Si TWIP Steel

The Fe-29Mn-3Al-3Si twin-induced plasticity (TWIP) steel is used to conduct quasi-static compression and dynamic impact deformation with strain rates ranging from 8.3 x 10(-4) to 3800 s(-1). The microstructures and properties of deformed samples under different strain rates were investigated comparatively. These results show that positive strain rate sensitivity was observed with the increase in strain rates and that there was a significant difference in strain rate sensitivity factor (m) between quasi-static compression (m = 0.029) and dynamic impact deformation (m = 0.190). Compared to the quasi-static compression, the dynamic impact deformation exhibited higher yield strength. Microstructural examination reveals that the primary twins were frequently found during the quasi-static compression process, and the secondary twins were rarely observed. However, the secondary and multi-fold deformation twins were florescent in the dynamic impact samples. At the initial stage of dynamic impact deformation, partial dislocations and staking faults on multiple conjugate {111} planes were simultaneously activated and produced a large number of Lomer-Cottrell dislocations, resulting in a large increase in yield strength during dynamic impact.

Automated summary

The study reveals that Fe-29Mn-3Al-3Si twin-induced plasticity (TWIP) steel exhibits significant strain rate sensitivity under different deformation rates, with dynamic impact deformation showing higher yield strength than quasi-static compression. Microstructural analysis shows the presence of secondary and multi-fold deformation twins in dynamic impact samples.