Effects of chemical composition and heat treatment on wear properties of backup rolls steel

Abstract

In this study, friction and wear properties of backup roll steels with different chemical compositions subjected to various heat treatment processes were investigated by optical microscopy, scanning electron microscopy and microindentation to figure out changes in microstructure during wear testing. The results showed that wear of backup roll was mainly consisted of sliding wear with some contribution from abrasive wear. The surface of backup roll material depicted obvious ploughing characteristics and plastic deformation zones after wear processing. The wear scar width, wear volume, hardened layer thickness and plastically deformed layer thickness of the backup roll material all decreased as substrate hardness increased. The wear resistance of the material enhanced with the matrix hardness. On the other hand, increasing contents of Mo, V, Nd and other elements influenced dispersion and fine grain strengthening. By comparison, increasing contents of C, Si and Mn affected the solid solution strengthening. Both methods improved wear resistance of the backup roll. The working layer of the backup roll produced by the integral induction hardening process was identified as mainly tempered martensite. In sum, the wear resistance of induction hardened backup roll significantly improved when compared to conventional differential temperature quenching.