NOUFERROUS METALLURGICAL EQUIPMENT

In order to further improve the Rockwell hardness and impact toughness of the grinding ball for mines, the mechanical properties, microstructure and phase characteristics of the grinding ball under different heat treatment conditions were studied. The results show that the microstructure of the grinding ball under different heat treatment conditions is composed of martensite, carbide and retained austenite. The microstructure characteristics of the matrix, the shape and distribution of carbide and the proportion of retained austenite all affect the performance of the grinding ball. With the increase of austenitizing temperature, the hardness increased first and then decreased, while the impact toughness decreased continuously. With the extension of austenitized holding time, both hardness and impact toughness increased first and then decreased. The hardness decreased continuously and the impact toughness fluctuation increased as the tempering temperature increased. With the extension of tempering holding time, the hardness does not change obviously, while the impact toughness decreased. For experimental grinding balls, the appropriate heat treatment process is to hold at 950℃ for 3h, and then quickly quenched in oil, and then tempered at 300℃ for 3h. Under this condition, the Rockwell hardness of the grinding ball is 62.58HRC and the impact toughness is 4.92J, which can be increased by 5.2% and 51.9% compared with the product grinding ball, respectively.