Effect of Austenitizing on the Microstructure and Mechanical Properties of Gray Cast Iron

This study enhanced the performance of gray cast iron through the precise control of the partial austenitizing temperature combined with an isothermal quenching process. The study investigated the effects of three austenitizing temperatures, namely 810 °C, 850 °C, and 900 °C, on the microstructure and mechanical properties of gray cast iron. With the increase in austenitizing temperature, the transformation of pearlite to ausferrite was promoted, and the ausferrite content increased from 8.0% at 810 °C to 91.2% at 900 °C. Mechanical property tests showed that the specimen treated at 850 °C had the best comprehensive performance. Its tensile strength reached 332 MPa, an increase of 78.6% compared with the as-cast state. The elongation increased by 51.8%, and the wear depth under a 20 N load decreased from 250 μm to 2 μm. Specimens with a high ausferrite content exhibited stable low-friction characteristics due to the uniform hardness and the suppression of adhesive wear. However, an excessively high austenitizing temperature of 900 °C would lead to an increase in residual stress in the casting and deformation of the graphite structure, reducing the wear resistance. Under the established austenitizing temperature conditions, this study explored the relevant mechanisms for the performance improvement of gray cast iron by means of various testing methods, providing a theoretical basis and process reference for optimizing the material performance of explosion-proof equipment under harsh mining conditions.