Effect of deformation twinning on high-temperature performance of cold-rolled S31042 steel

Influence of deformation twinning on high-temperature instantaneous performance of cold-rolled S31042 steel was investigated by optical microscopy, scanning electron microscopy, transmission electron microscopy, and high-temperature tensile test. An increasing number of deformation twins have formed as the cold rolling reduction degree increases during the cold rolling process. During the tensile process at 700 °C, M23C6 particles generated along the deformation twin boundaries, and NbCrN nanoparticles dispersedly precipitated throughout the austenite grains. For the high-temperature tensile sample subjected to cold reduction for 80%, it is observed from the fractured cross section that numerous deformation twin boundaries were decorated by discontinuous M23C6 particles. Therefore, austenite grains were divided into several independent zones by the deformation twins, and the grains were refined. Due to the grain refinement strengthening and precipitation strengthening, the high-temperature temporal strength of the 80% cold-rolled sample was significantly improved, and simultaneously, this sample exhibited favorable high-temperature elongation.