The Study On Heat Treatment Technology Of 55Cr5SiMoVNi Abrasive Cast Steel

With the development of modernization, the demand on abrasive cast steel has been increasing. In this paper, three kinds of medium alloy abrasive casting steel was designed, and the technology of heat treatment was studied on the base of analysis of properties and microstructure of imported cuter. It is aimed at finding the abrasive cast steel with comprehensive perfect properties and its heat treatment technology. In the meantime, the influence of multi-heat treatment and isothermal quenching were studied on microstructure and property, abrasion resistance and mechanism of fracture with different heat treatment.The results show that the imported cuter was made by forge. It has excellent properties with hardness 55HRC and impact toughness 58.5J/cm2. Furthermore, it has excellent work-hardening property. Its microstructure is fine and uniform, and its crystal grain size is over 12 grade. The mechanism of fracture is ductile fracture.The properties of three kinds of material are different at the condition of identical heat treatment. The properties of same material is also different at the condition of different heat treatment, and the fracture mechanism is very different. The properties of material A is better than the other two kind of material, and its chemical composition includes 0.55%C, 1.0%Si, 0.5%Mn, 5.0%Cr, 0.3%Nk 1.3%Mo and 1.0%V.The study on multi-heat treatment shows that tempering temperature and austenitizing temperature the first stage have great influence on properties. Crystal grain is fine and segregation can be reduced by normalization treatment before multi-heat treatment. Hardness reached to 53.5HRC and impact toughness 31.9J/cm2.The study of isothermal quenching shows that the quantity and size of bainite increase withthe isothermal time, hardness and impact toughness decrease. But the impact toughness increases when the isothermal time is over 3h.The test shows that the abrasion resistance of material A reached the level of imported cutter's after multi-heat treatment and isothermal quenching. The cost of test steel is cheaper, and the price is one-fifth of imported cutter's. The test steel is a new kind of material which is worth popularizing.