Study On The Effect Of Laser Parameters On Laser Repair

There are a large number of cracks like defects in the material and engineering structure.These cracks like defects are easily extended when the components and structures bear external loads,which not only reduces the bearing capacity of the materials and structures,and may eventually lead to the normal work of parts,parts,and even the whole machine,and may even lead to major disasters.The accident caused great loss of life and economy.The existence of crack defects greatly shortens the effective life of service products.For valuable,key parts and core components with long manufacturing cycle and high precision requirements,repairing crack damage can save resources and energy,and has remarkable economic benefit.Therefore,it is of theoretical value and practical value to study crack repairing methods for preventing further expansion after cracks.In this paper,laser repairing technique at the crack tip of 304 stainless steel compact tensile specimen is studied.Based on ABAQUS finite element software,the temperature distribution of laser repair at crack tip was simulated under different parameters.The results show that the depth and width of the molten pool increase with the increase of laser power,increase synchronously with the increase of heating time,and decrease with the increase of spot diameter.The shape of the molten pool is symmetrically distributed relative to the center of the beam,and the highest temperature points on the isotherms of the molten pool are located at the center of the beam.The fracture parameter COD values of the repaired specimens under different laser parameters are analyzed.The effect of laser process parameters on the fracture properties of repaired specimens is obtained.The results show that the fracture properties of the specimens are improved after laser repair.With the increase of laser power,the COD value of the repaired specimen becomes smaller,that is,the fracture property becomes better,the COD value of the repaired specimen increases with the increase of the light spot diameter,that is,the fracture property becomes worse,and with the increase of heating time,the COD value of the repaired specimen becomes worse.The COD value of the repaired specimen first decreases and then increases,that is,the fracture property becomes better and worse.The microstructures of the repair layer of the specimen were observed under different laser parameters.Microstructure and morphology.The effect of laser process parameters on the microstructure of the repaired specimen was obtained.The results show that the microstructure of the repair zone is smaller and denser than that of the matrix.When laserpower is too small,porosity is easy to occur;too large spot diameter will lead to incomplete melting of alloy powder;too short heating time will lead to incomplete melting of alloy powder,and too long time will easily lead to cracks in the repair layer.Finally,The order of influence of laser parameters on fracture properties of specimens was obtained by orthogonal test: the influence of spot diameter is the greatest,the influence of heating time is the second,and the influence of laser power is the least.In the range of selected laser parameters,the repair parameters are optimized.The optimal combination of laser parameters based on the fracture properties of the specimen is as follows: laser power2000 W,spot diameter 2mm,heating time 1.0s.