Developing a graphitic white iron for abrasive wear application: Thermal and wear properties

Abstract

Abstract Frictional heat generated in high speed sliding and rolling wear generates a significant amount of heat. Metal loses a large portion of hardness at high temperature, making it more susceptible to failures. Temperature rise due to abrasive wear on contact surface is a serious issue that limits the lifetime of many metal-to-metal contact wear systems. Five flake graphite containing white irons with different chromium and carbon contents (graphitic white irons) were designed, cast and investigated by the authors to solve this problem. This study examined the introduction of flake graphite into a white iron to increase the net thermal diffusivity, and to improve the abrasive wear resistance. Thermal diffusivity was measured using the laser flash method following ASTM E1461 and thermal diffusivity increased with increasing graphite volume percentage. Abrasive wear resistance was evaluated utilizing a dry sand/rubber wheel apparatus following ASTM G65 Procedure A, and it was found that 1\u202fvol% graphite was equivalent to an increase in wear resistance resulting from a hardness increment of 2.3 HRC, which benefited from the evaluated thermal diffusivity. Several numerical models were established to correlate hardness, microstructure, thermal and wear properties with the developed carbon equivalent. Comparisons with other commonly used alloys showed that the graphitic white irons had comparable wear performance to a premium high molybdenum, high chromium, white iron, but the alloy cost was 90% lower.