2013 Volume 54 Issue 633 Pages 913-917
The formation mechanism of edge-seam defects at the edges of hot-rolled strips of ferritic stainless steel was examined experimentally using a ferritic stainless-steel slab and crystal plasticity finite element analysis. Wrinkles in rolled strips occur owing to differences in deformation between coarse grains formed in orientation rotation as the reduction ratio increases, determined on the basis of the crystal anisotropy of coarse grains with random orientations that were formed during slab heating. In the initial stage of hot rolling, the depth of wrinkles increases with the diameter of such grains. Because the T.D. deformation of {111} is small and that of {001} is large, a grain sandwiched between {111} and {001} grains undergoes a large amount of deformation owing to the large constraining force of the grain boundaries of such grains. As a result, the formation of edge-seam defects is divided into two stages. In the early stage, wrinkles are formed by the crystal anisotropy on the side of the slab. In the second stage, those wrinkles extend toward the strip surfaces as a result of bulging during horizontal hot rolling.
