The effect of heat treatment on the abrasion resistance of alloy white irons

The effect of the temperature and time of the destabilization and sub-critical heat treatments on the abrasive wear behaviour of two high-chromium white iron alloys (15-3 Cr-Mo and 27 Cr) was investigated. The response of each alloy to the destabilization heat treatment and, therefore, the microstructures developed, differed significantly. Pin abrasion tests were conducted, and showed the wear resistance of the 15-3 Cr-Mo alloy to be superior to that of the 27 Cr alloy for most conditions. Following abrasion testing, retained austenite measurements using X-ray diffraction and microhardness measurements on the wear pins indicated the extent of austenite transformation and work-hardening. The work-hardening due to abrasion was greater for the 15-3 Cr-Mo alloy and this was related to the difference in composition of the matrix of each alloy. Abrasion on garnet and on alumina produced similar levels of work-hardening for both alloys, despite the differences in the abrasive hardness. Sub-critical heat treatments increased the abrasive wear loss. In particular, the formation of ferrite/carbide aggregates during the sub-critical heat treatment greatly increased the wear rate. (C) 1997 Elsevier Science S.A.