Effect of batch and continuous annealing processes on crystallographic texture and formability of an if steel

Abstract

IF (interstit ial free) steels are used in many applicatio ns, specifically in automotive industry due to their excellent formability. This formability behaviour is directly related to the annealing process, which influences both the crystallographic texture and the related "r value". For annealing, two main routes, namely batch and continuous annealing processes, are used in the production of IF-steels. The present study aims at comparing the same grade of IF steels produced via batch and continuous annealing processes. For this purpose, the texture and microstructure analysis were performed by electron backscatter diffraction (EBSD) technique in a scanning electron microscope (SEM). The formability behaviour of the steel sheet was characterized by determining the hardening curve and yield surface. It has been found that all samples show a strong ND fiber; {111}//ND. On the other hand, the drawability and related "r value" of continuously annealed samples were better than batch annealed ones. This behaviour is explained by the ultra-low carbon content, lower yield strength and equiaxial grain structure. © Copyright 2017 MS&T17®.