The Study On Fatigue Of High-speed EMU Axle Surface Reinforcement Layer

The rapid development of China's high-speed railway technology is the result of the development of the country's overall industrial level.Therefore,the study on fatigue of axle is the primary consideration for the strength checking of railway vehicles.This paper research the basic fatigue and fracture mechanical properties of S38C axle steel used in the CRH2 EMU trains.The obtained experimental data provided the basis for the determination of the reasonable maintenance cycle and life management method of the S38C axle.The contents of this paper can be summarized as follows:1.A series of basic research conducted on the S38C axle steel material taken from the actual axle.Obtain the main chemical composition,metallographic structure and gradient of hardening of S38C axle steel hardened layer.By thermal simulation test explore the heat treatment parameters of S38C axle hardening layer,and compare the structure and hardness of hardened layer of the actual axle.The confirmed heat treatment will be used to process the fatigue test and fracture mechanics test specimen.2.Research the basic fatigue properties of S38C axle steel materials by high frequency fatigue testing machine.By three point bending specimen test the bending fatigue property of S38C axle steel,and obtain the fatigue limit of the S38C axle steel material in the specified confidence interval and reliability.In the end,the p-S-N curve is gained.3.Research the fracture mechanics performance of S38C axle steel material,gain the surface strain fracture toughness of S38C axle steel material under certain thickness.4.Research the fatigue crack propagation rule of S38C axle steel material,by combining four different reliability models,gain the crack propagation equation under different reliability,and obtain the p-da/dN-?K curve.The test data of S38C axle steel material provided support in fracture mechanics performance.