Effects of Reduction Partitioning in Two-Stage Cold Rolling on the Surface Ridging Resistance of Ferritic Stainless Steel

The effect of reduction partitioning in two-stage cold rolling on the microstructure, texture, and ridging resistance of ferritic stainless steel was investigated to obtain the optimal process to improve the surface quality of the sheets. In the present study, four different cold rolling processes were employed: conventional cold rolling without intermediate annealing (i.e., Route 1) and two-stage cold rolling with three different reduction partitionings (i.e., Routes 2, 3, and 4). In Route 1 final annealed sheets, significant surface ridging defects were observed due to relatively large grain sizes, pronounced oriented grain colonies and size grain colonies. The ridging resistance of the final annealed sheets in the two-stage cold rolling process improved compared to Route 1. In two-stage cold rolling, the optimal ridging resistance was obtained when the first-stage cold rolling employed a 50% reduction and the second-stage cold rolling employed an 80% reduction. The results show that the texture is mainly shifted from α-fiber orientation to γ-fiber orientation. Additionally, decreasing the {001} < 110 > orientation volume fraction, improving the uniformity along the γ-fiber texture, increasing the γ-fiber intensity, and decreasing the average grain size of the final annealed sheets can improve the ridging resistance of the sheets. Moreover, eliminating orientation and size of grain colonies to achieve a uniform distribution is a key factor in improving the ridging resistance of the sheets. The appropriate reduction partitioning is a crucial factor in determining the ridging resistance of two-stage cold rolling final annealed sheets.

Graphical Abstract