Tribological properties of self-lubricating bronze-graphite composite against Fe-based alloys

Abstract

Purpose - The purpose of this study is to investigate the tribological properties of society of automotive engineers (SAE) 430B bronze-graphite composite, supplied in the form of machined and graphite embedded, used in sheet forming industry. Design/methodology/approach - Pin-on-disc wear tests were performed under a constant normal load of 15 N and a sliding velocity of 60 mm/s. Due to the extended usage of Fe-based alloys in forming dies, pin materials were selected as cold work tool steel, gray and ductile irons. The weight losses of the disc (SAE 430B bronze-graphite composite) and the pins (Fe-based alloys) were measured separately under various sliding distances (5,000, 10,000 and 15,000 m). The average friction coefficients and wear tracks were obtained. Findings - It is concluded that dry sliding behavior of SAE 430B bronze-graphite composite is the worst when operated with GGG-70 ductile iron due to its highest abrasive effect. The high hardness and nodular shape of graphite increased the abrasiveness of ductile iron. The improvement in wear resistance reached up to maximum 90 per cent and the degradation in friction coefficient was about 50 per cent by embedding graphite solids in bronze disc at dry sliding conditions. Originality/value - Although the machined and graphite embedded bronze composites are indispensable parts of forming dies, there is no scientific knowledge on their dry sliding behavior.