Influence Of Trailing Colding On Temperature Field Stress Deformation And Microstructure Properties Of Arc Additive Manufacturing

Aiming at the problems of poor forming quality,low dimensional accuracy and large residual stress inside the formed part after the accumulation is completed due to the serious heat accumulation in the arc additive manufacturing process.This paper proposes a trailing cold source arc additive manufacturing method to improve the serious heat accumulation in the arc additive manufacturing process and reduce the residual stress inside the formed part.The method of combining numerical simulation and experiment is used to study the influence of the trailing cold source on the temperature field and stress and strain in the arc additive manufacturing process.Finally,the microstructure and mechanical properties of the accumulation layer are analyzed,and the influence of the trailing cold source on the microstructure and mechanical properties of the arc additive manufacturing forming parts is studied.Based on ANSYS,a finite element model of the temperature field under the conditions of additive manufacturing with and without cooling source was established,The thermal cycle curve of points on the substrate was tested experimentally,and the simulation results were compared to verify the accuracy of the establishment of the temperature field finite element model.Based on the finite element simulation results,the following conclusions are drawn: Compared with no cold source,the temperature of the substrate when the heat source reaches the midpoint of the fifth and tenth layers of the buildup layer under the condition of cold source additive manufacturing is reduced by 70°C and 113°C,respectively.The existence of a cold source can effectively reduce the amount of heat accumulation on the build-up layer and the substrate.Compared with no cold source,the maximum temperature of the molten pool when the heat source reaches the midpoint of the first layer,fifth layer,and tenth layer under the additive manufacturing condition of cold source is reduced by 35°C,87°C and 92°C,respectively.When there is a cold source,the forming quality of the accumulation layer can be improved.Based on ANSYS,the finite element model of the stress field under the conditions of additive manufacturing with and without cold source was established.The residual stress measured at the calibration point is compared with the simulation result,which verifies the accuracy of the establishment of the stress field finite element model.Based on the finite element simulation results of the stress field,the following conclusions are drawn: The residual stress inside the formed part determines the final deformation of the formed part,The residual stress inside the formed part mainly depends on the longitudinal stress,and the size and distribution of the longitudinal stress determine the final deformation of the formed part.Compared with no cold source,the longitudinal residual stress inside the accumulation layer under the condition of cold source additive manufacturing is reduced by 17.6%.Due to the cold source,the longitudinal stress level on the formed part can be reduced,the final deformation of the formed part can be reduced,and the dimensional accuracy of the formed part can be improved.Compared with no cold source,the maximum node displacement on the formed part under the cold source additive manufacturing condition is reduced by 24%.Since trailing cold source arc additive manufacturing can effectively improve the heat accumulation during the forming process and accelerate the cooling rate of the molten pool,it will inevitably have an impact on the structure and performance of the accumulation layer,Comparing the structure and performance of the accumulation layer under the additive manufacturing conditions with and without cooling source,the results show that the grain size of the accumulation layer is smaller under the additive manufacturing conditions of the cooling source.Under the condition of cold source additive manufacturing,due to the fine grain size of the build-up layer,the tensile strength and elongation of the build-up layer are significantly improved,Compared with no cold source,the tensile strength of the accumulation layer under the condition of cold source additive manufacturing is increased by 10%,The microhardness of the accumulation layer is also slightly improved under the condition of cold source additive manufacturing...