The effects of austenitising temperature and temper treatment on the microstructure, hardness and abrasive wear resistance of a high carbon high vanadium high speed steel roll of composition 2?2-2?4C, 5?5-6?5V, 4?5-5?5Cr, 14?0-16?0(Wz2Mo), 1?0-1?4Ni and 1?2-1?5Nb (wt-%) were investigated by light optical microscopy, scanning electron microscopy, backscattered electron image, X-ray diffraction and hardness and wear testing. It was found that the hardness increases as the austenitising temperature increases to a maximum of 1050uC, and then begins to decrease because of the increase in retained austenite. Moreover, retained austenite begins to transform into martensite with increasing tempering temperature. The retained austenite in the quenched structure leads to the temper hardening of the rolls, which promotes improved abrasive wear resistance. The roll life of high carbon high vanadium high speed steel compound rolls austenitised at 1050-1080uC and tempered at 540-560uC increased by 400% (single groove trials) compared to high nickel-chromium white cast iron rolls when the rolls were used in a K1 mill housing of a bar mill.

The authors describe the researching results to optimise the hardening and tempering of the high carbon high-speed steel for rolls containing 2.38%C, 5.07%V, 6.34%Mo, 5.09%Cr, 1.20%Ni, 1.17%Nb, 0.09%Ti and 0.05%RE by means of light optical microscope (LOM), scanning electron microscope (SEM), backscattered electron image (BSE), X-ray diffraction (XRD), and hardness, tensile strength, impact toughness and wear testers. The results show that the microstructure of above casting high-speed steel is given by a tempered martensitic matrix surrounded by eutectic carbides. Casting high-speed steel has higher hardness quenching at 1280 K -1340 K, and it has higher hardness, tensile strength, impact toughness, and abrasive wear resistance tempering at 793 K -833 K. The comprehensive properties of casting high-speed steel is the best while air-cooling quenching about 1340 K and tempering about 813 K.