离心铸造辗扩成形42CrMo钢环件热处理后的组织与性能

Microstructure and properties of 42CrMo steel ring formed by centrifugal casting and ring rolling after heat treatment

为实现42CrMo离心铸坯辗扩成形环件良好的综合力学性能,对热辗扩后成形环件采用840℃水淬及590℃回火调质处理,对其显微组织和力学性能进行检测,并对拉伸及冲击断口形貌观察。结果表明:辗扩后环件平均晶粒尺寸较小,中层晶粒相对内、外层的粗大;经过调质处理,辗扩残余应力得到释放,晶界活性增加,晶粒发生一定程度长大,显微组织由层片状珠光体转变为回火索氏体,断裂形式由解理断裂转变为韧性断裂;强度、硬度有所降低,但塑韧性明显提高,综合力学性能良好,满足了技术条件要求。

In order to achieve good mechanical properties of 42CrMo steel ring formed by centrifugal casting and ring rolling, the ring was quenched at 840 ℃ and tempered at 590℃ after ring rolling. Mechanical properties and microstructure of the ring were detected, and tensile and impact fracture morphologies were observed. The results show that the average grain size of the rolling ring is small, and the grain size in the middle layer is relatively coarse than the inner and outer layer. After quenching and tempering, the crystal grain grows up to a certain extent because the residual stress is released and the activity of grain boundaries is increased and the microstructure changes from lamellar pearlite to tempering sorbite, the fracture form changes from cleavage fracture to ductile fracture, and the strength and hardness decrese to a certain extent while ductility and toughness improve significantly, the good comprehensive mechanical properties can be obtained and meet the technical requirements.