Experimental study on the evolution law of residual stress in the fatigue process of inductively quenched 42CrMo steel

Abstract

In the process of remanufacturing a crankshaft with a history of service, it is found that the residual stress of the crankshaft will relax during operation. Therefore, the relaxation of residual stress must be considered in the study of crankshaft remanufacturing. X-ray diffraction is used to measure the initial and final residual stresses after each loading cycle, and the changes in the microstructure of the material after induction quenching were also measured by scanning electron microscopy. The results show that the maximum residual compressive stress appears inside the sample, and its size decreases with increasing depth. The relaxation of residual stress on the surface of the sample with hardened layer can be roughly divided into three stages: rapid relaxation, stable relaxation, and instantaneous release of the final fracture residual stress. An empirical model is proposed to estimate the residual stress relaxation, considering the depth of the hardened layer and the external load during the fatigue process to predict the relaxation law of the residual stress.