Dry sliding wear properties of sub-microcrystalline ultra-low carbon steel produced by high-pressure torsion straining

Abstract

This study is the first to show dry sliding wear properties of sub-microcrystalline ultra-low carbon steel produced by high-pressure torsion (HPT) straining. Effects of number of turns in HPT process and counter materials in wear tests were investigated using a ball-on-disc friction method.Wear tests were carried out in a normal laboratory atmosphere of air at a sliding speed of 0.042m/s and an applied load of 39.6 N. When the ball material was cemented carbide (WCCo), the wear depth of HPT-processed discs decreased with increasing the number of turns in HPTstraining. This was explained by the hardness variation, i.e. the HPT-processed discs in which large strain was introduced exhibit high anti-wear resistance due to the high hardness. On the other hand, when the ball material was high carbon-chromium bearing steel (SUJ2), the wear depth of disc specimens increased with increasing the number of turns. The unusual behavior of the wear depth variation was thought to be attributed to the intensive adhesion between the HPT-processed steel disc and the SUJ2 ball because the coefficient of friction was considerably high for the ultra fine-grained specimens. © 2011 The Japan Institute of Metals.