Study On Effect Of Surface Hardness On Contact Properties Of PSHG Parts

With the rapid development of mechanical manufacturing industry,the contact fatigue failure of mechanical parts has attracted more and more attention,Surface integrity of components has had a huge impact on the rolling contact fatigue performance.New surface hardening treatment technology was more concerned.Pre-stressed hardening grinding is a new surface processing technology which can hardening the workpiece surfaces by using grinding heat,and applied prestress to control the residual stress.The influence rule of the pre-stressed hardening grinding 45 steel specimens surface hardness on the rolling contact fatigue was studied based on the combined method of experiment and theoretical analysis and finite element simulation.Specific research work as follows:(1)The rolling contact fatigue test was designed to investigate the relationship between rolling contact fatigue properties of PSHG composite processing 45 steel specimens with surface hardness.The traditional friction and wear testing machine was transformed into rolling contact fatigue testing machine with the new rolling contact pair.The rolling contact fatigue test was carried out on PSHG composite 45 steel specimen with different surface hardness.The influence of surface hardness on the rolling contact fatigue was analyzed by comparing the fatigue damage of the contact area on the surface of the specimen.(2)Based on the 45 steel specimens surface hardness induced by pre-stressed hardening grinding,a rolling contact fatigue(RCF)life predict model is proposed.Based on rolling contact theory,the surface contact stress of the part is calculated and analyzed.Considering the factors of surface hardness and surface stress,the fatigue life model was established based on the local S-N curve and fracture mechanics theory.The rolling contact fatigue(RCF)life of PSHG composite 45 steel specimen with different surface hardness was calculate by using the model.(3)ABAQUS finite element software was used to analyze the rolling contact model of PSHG composite 45 steel specimen with different surface hardness.First,the surface hardness can be converted to other mechanical properties which can be input to the simulation.Then the static and steady contact stress,ratcheting effect and rolling contact fatigue life of PSHG 45 steel specimens with different hardness were analyzed.The impact mechanism of surface hardness on the contact properties of PSHG composite specimens were investigatedThe results show that the rolling contact fatigue properties of PSHG 45 steel specimen are enhanced with the increase of surface hardness in a certain range of hardness.The crack initiation position is about 30 ?m away from the surface,and the crack initiation life is about 80%of the total life.When the surface hardness is too large,the brittleness of the material increases,and the contact property of the parts may be deteriorated.The results of the three analytical methods are consistent and can be compared with each other.The surface integrity parameters of the workpiece after PSHG composite processing are determined by the process parameters.The influence of specimen surface hardness on the rolling contact fatigue properties and the influence of PSHG composite processing parameters on the surface hardness of the specimen can be used to provide research foundation.for the development of PSHG composite processing.