Numerical Simulation Of Temperature Field And Stress Field Of Coaxial Powder Feeding Laser Cladding And Its Parameter Optimization Research

Recently,with the continuous development of laser cladding technology,it has been gradually used to manufacture,repair or remanufacture various industrial parts,and has been applied to many fields such as automobiles,energy,electronics,aerospace,and medical.Laser cladding technology can improve the performance of raw materials,extend the life of components and expand the range of applications.The temperature distribution and stress distribution of laser cladding will affect the processing quality.The numerical simulation can explore the distribution of temperature and stress fields.The difference in temperature field distribution between the molten pool and its surrounding during the cladding process will have a significant effect on the quality of the final cladding layer,and the residual stress generated by the heating and cooling process will affect the geometric properties and mechanical properties of the cladding layer.Due to the small range of the molten pool and the extremely fast heating and cooling process,it is difficult to obtain the variation of the temperature field and the stress field completely by experimental methods using existing equipment.Therefore,the numerical simulation method is used to study the three-dimensional transient temperature field and stress field of coaxial powder feeding laser cladding,and the distribution law of temperature field and stress field of single-pass and multi-channel laser cladding is obtained.The variation of the morphology was verified by experiments.The main contents include:(1)The variation of the temperature field of single-pass laser cladding and single-layer multi-pass laser cladding was analyzed and compared.Parametric programming was performed using the finite element analysis software ANSYS.The results show that the maximum temperature at the edge of the single-pass cladding layer is significantly higher than that at the middle.In actual processing,defects can be avoided by adjusting the process parameters.The comparative analysis of the influence of process parameters on the temperature field provides a theoretical basis for the optimization of process parameters.In addition,the temperature distributions of the six scanning methods of single-layer multi-channel laser cladding were compared.The results show that one-way scanning method avoids local short-term energy accumulation compared to reciprocating scanning method;There is no obvious difference between the scanning method along the long axis direction and the short axis direction;The spiral scanning method can ensure the continuity of the processing process and avoid the temperature fluctuation between the tracks of other scanning methods.(2)On the basis of temperature field simulation,the stress field distribution law of laser cladding is obtained by sequential thermal coupling.The results show that the surface of the cladding layer is mainly subjected to tensile stress after laser cladding,and the substrate is mainly subjected to compressive stress.Comparing the stresses in different directions,the residual tensile stress in the scanning direction is the largest,so the crack is more perpendicular to the scanning direction.Using the Mises stress,the maximum stress occurs at the junction of the cladding layer and the substrate and at the center of the cladding layer.In multi-channel cladding,the residual stress distribution in the one-way scanning method along the short axis direction is superior to other scanning methods,while the spiral inward scanning method obtains the largest residual stress.The residual stress distribution can be significantly improved by increasing the preheating temperature.(3)The process parameter optimization experiment of single-pass laser cladding was carried out by response surface method.The 316L stainless steel was welded on 45#steel,and the influence of process parameters on aspect ratio and dilution rate was obtained,which was consistent with the finite element analysis.The surface morphology of the cladding layer obtained by the six scanning methods was measured experimentally,and the surface quality of the cladding layer obtained by the spiral outward scanning method was the best.