Establishing the Rolling - Friction Coefficient for Different Contacts Between Balls and Termochemicallly Treated Steel Rolling Paths

Abstract

Within the frame of this work, the influence of four very well-known and often used thermochemical treatments (carburizing, carbonitriding, nitriding and nitrocarburizing) of steel rolling paths applied on rolling-friction coefficient has been studied. The rolling - friction tests supposed different arrangements of the semi-couples (plates) and intermediary balls. Because of the difficulty in estimating the value (dimension) of the rolling friction coefficient, an equivalent static friction coefficient μ₀ (at the start) was established for all the couples. According to the experimental results of this study, the carburized rolling paths seemed to offer the best conditions for rolling, the initial move appearing at the earliest. In addition, the presence of  nitrogen and the possible FexN compounds on the contact rolling surface leads to an increased friction coefficient μ₀. Finally, the study demonstrated that there is a slight tendency for a certain decrease in μ₀ when increasing the intermediary balls diameter.