Deformation mechanism of cryorolled Fe-36%Ni strip steel

State Key Laboratory of Rolling and Automation, Northeastern University, Shenyang 110819, PR China

^a Corresponding author: e-mail: lics@ral.neu.edu.cn

Abstract

The deformation mechanism of cryogenic rolled Fe-36%Ni steel is investigated with rolling strain of ε = 0.24–0.92. Experimental results show that both dislocation slip and twinning are activated at cryogenic temperature as strain ε = 0.24, and the mean thickness of deformation twins is about 200 nm. When the rolling strain increases to 0.53, the mean thickness of deformation twins reduces to 50 nm and some curved deformation twins exists. As the rolling strain increases to 0.92, the thickness of deformation twins is no longer changed and the micro shear bands exist due to the concentration of work hardening, which suggests that twinning is activated at the early stage of cryogenic rolling (CR) process. It is assumed that more deformation twins will be fragmented by shear bands during the following CR. The dislocation slip becomes the dominated mechanism again during the following deformation. The mechanism of the Fe-36%Ni steel following CR was analyzed quantitatively.