调质钢的热处理一般是淬火后经过低于临界点Ac_1温度的高温回火。我厂有一个产品零件,材料是38调质钢(化学成分是:碳0.34～0.42％,硅0.17～0.37％,锰0.50～0.80％,磷小于0.35％,硫小于0.03,铬0.80～1.10％,镍小于0.40％),要求的机械性是:屈服强度80公斤/毫米~2,抗拉强度95公斤/毫米~2,延伸率12％,断面收缩率50％,冲击韧性值9公斤一米/厘米~2,硬度R_c32～38。这种钢在退火或正火状态下的性能不能达到这些要求,但用一般调质处理,高温回火所占的 Heat treatment of quenched and tempered steel is generally quenched after the temperature below the critical point Ac_1 tempering temperature. I plant a product parts, the material is 38 quenched and tempered steel (chemical composition: carbon 0.34 ~ 0.42%, silicon 0.17 ~ 0.37%, 0.50 ~ 0.80% manganese, phosphorus less than 0.35%, sulfur less than 0.03, chromium 0.80 ~ 1.10% , Nickel less than 0.40%), the required mechanical properties are: yield strength of 80 kg / mm ~ 2, tensile strength of 95 kg / mm ~ 2, elongation of 12%, 50% reduction in area, impact toughness value of 9 kg / Cm ~ 2, hardness R_c32 ~ 38. The performance of this steel in the annealed or normalized state can not meet these requirements, but with the general quenching and tempering, high temperature tempering accounted for