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本文研究了表面形变强化对不同热处理状态的45Cr钢三点弯曲、不对称循环下疲劳强度的影响,并用x射线衍射法测定了残余应力的分布及半高宽,用电镜观察了断口形貌和断裂特征. 表面形变强化后材料疲劳强度的提高可归结为宏观残余应力、表面光洁度和组织结构变化三个基本因素. 高温回火试样经滚压强化后,其组织结构变化既有组织强化又有组织损伤,它对疲劳强度的影响比残余应力要小些.但当残余应力衰减较剧时,它又会成为影响疲劳强度的主导因素. 低温回火试样的形变强化效果显著.除了残余压应力的有利因素外,材料表层回火马氏体微观不均匀性的改善也对疲劳抗力的提高起了重要作用.
In this paper, the effect of surface deformation strengthening on the three-point bending and asymmetric cyclic fatigue strength of 45Cr steel under different heat treatment conditions was investigated. The distribution of residual stress and FWHM of the 45Cr steel were measured by X-ray diffraction. Fracture characteristics.The improvement of the fatigue strength of the material after the surface deformation strengthening can be attributed to the three basic factors of macroscopic residual stress, surface finish and structure change.After rolling strengthening, the microstructure of the specimen after high temperature tempering has both the strengthening of the structure It has less effect on the fatigue strength than the residual stress.However, when the residual stress attenuates more, it will become the dominant factor affecting the fatigue strength.The deformation strengthening effect of the low temperature tempering specimen is significant.Although the residual In addition to the favorable factors of compressive stress, the improvement of microscopic nonuniformity of tempered martensite on the material surface also plays an important role in the improvement of fatigue resistance.