Wear and Friction under Rolling with Slip

Abstract

Wear of steel rail has been the subject of extensive laboratory as well as field investigations. A number of variables such as load, speed, weather conditions, wear fragments, extraneous grit, battering of rail ends, etc. have been shown to exercise profound influence indivi-dually and jointly on the wear of steel rail. Effect of longitudinal relative slip between the rail and the wheel on the wear of steel rails was, therefore, carried out under conditions of nominally pure rolling and with rela-tive slip up to the extent of fifteen per cent. Studies were made under both sets of conditions viz. predominantly adhesive (wear fragments removed) and self-abrasive (wear fragments not removed). The nature of variations of wear rate and friction with percentage of relative slip has been shown to be uniquely related with the nature and size of wear fragments, surface conditions of the test discs and the sub-surface metal flow ; the contribution of each factor having been discussed separately. The cause of rela-tively high wear rate and lower friction in case of wear fragments not removed and lower wear rate and higher fric-tion in case of wear fragments removed has been traced particularly to the surface energy of the wear fragments produced.