1前言某些机械零件如轧钢机组用的接轴、齿轮轴等，由于服役条件不同，不仅要求有较高的强度、同时要有良好的塑性和韧性以及抗疲劳等性能，即需具备好的综合力学性能。为满足上述要求，一般选用含碳量在0．30％～0．50％的优质碳素结构钢如45钢或合金结构钢35CrMo等牌号用调质 1 Preface Some mechanical parts such as rolling mills with the shaft, gear shaft, due to different service conditions, not only requires a higher strength, good ductility and toughness and fatigue resistance and other properties, you need to have a good Comprehensive mechanical properties. In order to meet the above requirements, the general selection of carbon content of 0.30% ~ 0.50% of high-quality carbon structural steel such as 45 steel or alloy steel 35CrMo grade with tempering