Effect of new type heat treatment on wear characteristics of high-strength sintered steels

The main aim of the paper is to study the influence of new type heat treatment - sinter hardening - on the wear characteristics of high-strength sintered steels. The wear behaviour of the chromium pre-alloyed sintered steels was investigated through pin-on-disk tests. Two different processing conditions have been used, involving different cooling rates from the sintering temperatures of 1180 °C, the first of which, identified as slow, implied a cooling rate of 0.05°C/s. The later cooling rate obtained applying a process called sinter hardening determined an average cooling of 6 °C/s. The role of the different chemical compositions has also been evaluated. The microscopic investigations reveal deformed layers and tracks along the direction of sliding during wear. Particular attention has also been paid to the friction coefficient and to the role of porosity on wear. The results showed that the microstructure characteristics represent an important parameter affecting the wear behaviour of sintered steels and sinter hardening is a suitable heat treatment for improving the wear resistance of sintered steels.