Influence of cold rolling on microstructure, texture and mechanical properties of low carbon high Mn TWIP steel

Abstract

The present study deals with the influence of cold rolling on microstructure, texture and mechanical properties of low carbon high Mn TWIP steel. It is noticed that the hardness, yield strength and tensile strength of the specimens increase whereas percentage elongation decreases as the amount of cold rolling reduction increases. The fully austenite phase with the average grain size of about 55µm along with annealing twins became fragmented and flattened when subjected to 10–50% cold deformation. The cold deformation results in the evolution of sub-structure, comprising dislocations, twins as well as interaction of dislocations and twins. The hot rolled and air cooled sample (0% cold deformation) reveals γ-fibre (〈111〉//ND) texture, whereas cold rolled samples shows Goss texture ({110}〈001〉) and Brass texture ({110}〈112〉) components, which are expected after cold deformation of austenitic steels having lower stacking fault energy in the range of 15–40mJ/m2. X-ray line profile analysis through extended convolution multiple whole profile fitting method is utilised to quantify the dislocation density and planar fault (twin) probability for the cold rolled samples with different degree of reduction. Fractography shows that with the increase in cold deformation, fractures become more and more brittle in nature.