Effect of Different Torsion Routes on Microstructure Evolution and Mechanical Properties of 0Cr12Mn5Ni4Mo3Al Steel Undergoing Deformation-Induced Phase Transformation

The microstructure evolution and mechanical properties of the 0Cr12Mn5Ni4Mo3Al steel subjected to single direction torsion (SDT) and torsion-reverse torsion (TRT) are investigated. The finite-element method (FEM) is used to obtain the value of the equivalent strain in different torsion routes. These results demonstrate that the size of the grain becomes more refined when undergoing SDT and TRT. With a decrease in the TRT angle, the distribution of α-phase appears like a kinked curve, and the grain refinement becomes less and less obvious. In addition, deformation-induced phase transformation emerges and results in ferrite and austenite concurrent rearrangements. Furthermore, the material hardening is mainly due to the increase in statistically stored dislocations (SSDs) and geometrically necessary dislocations (GNDs) with the accumulation of the equivalent strain and the strain gradient. Finally, the fracture mechanism is also discussed to reveal the strength ductility of the samples.