Research Of Numerical Simulation Of Stress Field And Interface Behaviour Of Ni201 Repair Layer By Electro-spark Deposition

The essence of electro-spark deposition is a kind of micro arc welding process,as a repair surface strengthening technology is of great significance to strengthen the repair of the damaged mechanical parts.In this paper,Ni201 repair layer on Q235 steel surface was prepared by DHD-6000 type electro-spark deposition equipment,interface behavior of Ni201 repair layer were studied.And temperature field and stress field of the electric-spark deposition was simulated analysis by establishing the finite element analysis model.The temperature field and stress field of the electro-spark deposition distribution were studied by using finite element analysis software ANSYS.By selecting the Gaussian heat source and loading reasonable thermal boundary conditions and displacement constraints,firstly calculate temperature field,then calculate stress field.The results show that the temperature of the substrate dramatic changes with the heat source moving,thermal stress is distributed mainly in the region of the temperature gradient larger,longitudinal residual tensile stress distribute along the direction of deposition center line,the maximum value is about 245 MPa,the areas of the deposition beginning and the end have residual compressive stress,the maximum value is 227.5MPa.The stress field is accord with theoretical results basically.The electric spark deposition experiment have been made by selecting process parameters,such as arc ratio,power output amplitude and frequency.The microstructure,chemical elements distribution,phase composition of the bonding interface between restoration layer and substrate,and residual stress on surface of restoration layer were investigated by means of scanning electron microscopy and energy dispersive spectrometer,and X-ray diffraction.The results show that the microstructure of Ni201 restoration layer is uniform and dense,the main phase of the layer is composed of Fe10.8Ni?(Fe,Ni)?CoFe15.7,the mutual diffusion between restoration layer and substrate form metallurgical bonding.It proves that the restoration layer of electro-spark deposition and substrate is not a simple mechanical bond.Repair lay surface residual stress increased with the increase of power output amplitude and arc ratio is tested by X-ray diffraction instrument,but within the material yield limit.In order to optimize the electro-spark deposition process and provide theoretical reference of reducing the repair layer surface residual stress,the effect degree of arc ratio,power output amplitude and frequency on the surface residual stress were analyzed by orthogonal experiment method.Results show that the influence of the three factors on surface residual stress from strong to weak is arc ratio,power output amplitude,frequency.Through comprehensive analysis the results of orthogonal experiment and quality of repair interface layer,the better process parameters of electro-spark deposition are as follows: frequency 1000 Hz,arc ratio 35%,power output amplitude 40%.