研究了用塑性区紧固法拧紧的柴油机气缸盖高强度螺栓的硬度和加工顺序对组装中的螺栓及螺栓本身疲劳极限的影响,获得了如下主要结论:①在螺栓平均硬度从HV300提高到HV400时,调质后滚丝的组装中的螺栓体的疲劳极限可提高20％,螺栓自身的疲劳极限可提高30％。②螺栓的平均硬度愈高,其初始紧固力(预紧力)就愈大,对受循环偏心载荷的组装件的分离特性的约束性也愈强,因此在螺栓上产生的循环应力就愈小。 The influence of the hardness of the high strength bolts of the cylinder heads of the diesel engine fastened by the plastic zone fastening method and the processing sequence on the fatigue limit of the bolts and bolts themselves during assembly are studied. The main conclusions are as follows: ①When the average hardness of bolts increases from HV300 to HV400 , The fatigue limit of the bolt body in the assembly after the tempering and rolling can be increased by 20%, and the fatigue limit of the bolt itself can be increased by 30%. ② The higher the average hardness of the bolt, the greater its initial tightening force (pre-tightening force) and the greater the constraint on the separation characteristics of the assembly subject to cyclic eccentric load, so the cyclic stress produced on the bolt small.