Effect of Annealing Treatment on Mechanical and Magnetic Softening Behaviors of Cold Rolled Interstitial-Free Steel

Abstract

The recovery and recrystallization behaviors of low-carbon interstitial-free steel are investigated at different annealing temperatures (200-690 °C) through correlation between the changes in magnetic parameters (coercivity and r.m.s. voltage), hardness, tensile strength and high-angle grain boundary fractions (HAB). Magnetic parameters and tensile strength show a significant change within recovery region (200-500 °C), while the hardness variation is very minimal at this temperature region. On the other hand, the hardness is abruptly changed compared to magnetic properties at higher annealing temperature (550-640 °C). The grain boundary characteristics and microtexture evolution occurring at recrystallization regime are evaluated by orientation imaging microscopy (OIM) and orientation distribution function (ODF) through electron backscattered diffraction (EBSD). The increase in recrystallization fraction noticeably affects microtexture property, justifying with the strengthening of γ-fiber, weakening of α-fiber and disappearance of rotated cube component with increasing annealing temperatures.