Deformation behavior of the surface defects of low carbon steel in wire rod rolling

High surface quality of low carbon steel wire rod is essential to forge mechanical parts since a small surface defect can initiate the crack propagation. The aim of this study is to investigate the deformation behavior of the surface defects with a notch shape on the billet in multi-pass hot rolling process using FE code, CAMProll. It is focused on the possibility that intentionally produced notches on the billet can diminish or grow when their initial sizes and locations are varied. The contact treatment for three-dimensional rolling simulation in order to prevent the penetration of free surface nodes into contact surfaces was implemented in CAMProll. It is assumed that initial surface notches do not propagate in the multi-pass rolling. From numerical simulations, it was found that oval-round rolling sequence was effective to reduce the notch depth although it could not eliminate the initial surface defects. And the initial location is more influential factor to determine the final notch size.