Effect of Heat Treatment on the Structure and Properties of the ChKh3 Low-Alloy Wear-Resistant Chromium Cast Iron

The effect of heat treatment on the microstructure, microhardness, and structural-phase state of the samples of the ChKh3 low-alloy wear-resistant chromium cast iron is studied. The metallographic analysis is performed using a Carl Zeiss Axio Observer Z1m metallographic microscope and ThixoMet PRO software. The heat treatment of the samples is carried out in a SNOL furnace equipped with a Termodat 16-E3 PID controller. After 2-h-long quenching at a temperature of 890°C, the samples are removed from the furnace and cooled in still air. After cooling to a temperature of 40–50°C, the samples are tempered at a temperature of 180–200°C for 2 h. The samples cooled after tempering have a hardness of 54–56 HRC compared to a hardness of 320–340 HB in the cast state. The results for heat treatment show that the main contribution to an increase in the hardness of the ChKh3 wear-resistant chromium cast iron is provided by a significant increase (by a factor of 2–2.5) in the hardness of the metal matrix due to solid-solution hardening and partial precipitation of fine inclusions (carbide particles). Tests of heat-treated shot blast blades made of the ChKh3 cast iron show an increase in service life by a factor of 8–11 compared to cast blades not subjected to heat treatment, and a factor of 1.5–2 compared to serial shot blast blades, made of the 510Cr2 cast iron in China.