Correlation between Luder strain and retained austenite in TRIP-assisted cold rolled steel sheets

In developed multiphase high strength, high formability TRIP-aided steel, Luders bands are observed similar to conventional low carbon steels. Retained austenite as the most effective constituent in TRIP steels, is responsible for Luders band formation as well as other properties such as formability, physical and mechanical properties.In the present study, a correlation between the Luders strain and the retained austenite characterization is proposed and verified by experimental evidences of the work carried out on two types of TRIP steel sheets. Intercritical annealing of cold rolled TRIP steels at different temperatures change the volume fraction of the retained austenite as well as the carbon concentration of samples which in turn leads to different Luders strain values. The experimental results show that the Luders strain is limited when the volume fraction and carbon concentration of the retained austenite increase in the TRIP steels.