Effects of Si on tensile properties associated with deformation-induced ε-martensitic transformation in high Mn austenitic alloys

We investigated the effect of Si on the tensile properties of Fe-33Mn, Fe-33Mn-4Si, and Fe-33Mn-6Si austenitic alloys (mass%) at 273, 294, 323, and 423 K. The Si addition promoted the deformation-induced ε-martensitic transformation, thereby enhancing the work-hardening capacity. In terms of Considère's criterion, the enhanced work-hardening capacity can improve uniform elongation. However, the Si addition simultaneously promoted brittle cracking associated with ε-martensite, tending toward decreasing elongation. As a result of the ambivalent roles of Si related to ε-martensite, the elongation-strength balance was improved by the addition of 4%Si, but was deteriorated when the Si content increased to 6%. As an additional effect, the Si addition changed the microvoid-formation behavior, resulting in decreasing local elongations.