The Effect of Elevated Temperatures and Speed Upon the Wear of Mild Steel

Abstract

This thesis describes an elevated temperature wear test rig specially designed to study the friction, wear and heat flow between specimens as a function of load, speed and externally - induced ambient temperatures. The pin and disc specimens used for these experiments were made from EN8steel. The variations of wear rate with load revealed wear rate transitions similar to those reported by Welsh ( 1964 ). The shape of the 'wear rate versus load' graphs were strongly dependant upon the externally -induced ambient specimen temperatures, It is shown that similar transitions and shapes could also be obtained by increasing the sliding speeds. The division of heat at the specimen interface was measured for selected experiments in which no external heating was supplied to the specimen. Using a surface model, a computer analysis of both the heat flow and the wear rate was carried out to find out how these results could be fitted to an oxidational wear theory and provide realistic estimates of surface temperatures during sliding. A critical analysis of this method and the difficulty encountered in fitting the computer analysis to an oxidational wear theory has been carried out. Physical and metallographic techniques were applied to worn specimen surfaces and wear debris.