Dynamic behaviors of 0Cr18Ni10Ti stainless steel welded joints at elevated temperatures and high strain rates

Dynamic mechanical behaviors of the base metal (BM) and the weld metal (WM) for the welded joints of an austenitic stainless steel, 0Cr18Ni10Ti, are studied at loading rates ranging from 200 to 3800 s^-1 and temperatures from 25 to 600 °C using a modified Hopkinson pressure bar system. We focus on the effects of strain, strain rate and temperature on the flow stress of the specimens. The results show that the work hardening rate and the sensitivities of the flow stress to strain, strain rate and temperature are affected by the testing temperature. The plastic deformation is dominated by the competition between thermal softening and strain/strain rate hardening, in keeping with the thermally activated dislocation motion theory. The stress-strain curves are successfully modeled by the Johnson-Cook (J-C) model and different plastic flow mechanisms are found for the WM and the BM through microstructure analyses.