Numerical Simulation Of Temperature Field Of Laser Cladding Technology Analysis

Laser cladding is widely used in forming and repairing parts.Laser cladding is a process of rapid cooling and heat.Temperature gradient,cooling rate and stress distribution in the forming process have direct effects on the quality of cladding layer.It is very difficult to measure the temperature field and stress field of the molten pool by experimental method at present.In this paper,the temperature field and stress field in laser cladding process are analyzed by numerical simulation,in order to reveal the growth mechanism of laser cladding structure,and the correctness of the model is verified by experiments.Firstly,parameterized programming based on APDL language of ANSYS is carried out,and the three-dimensional transient single-channel,multi-channel lap and multi-layer laser cladding temperature field finite element model under the action of moving laser heat source is established.The effects of laser cladding process parameters(laser power,scanning speed,spot radius)on temperature field,the variation of temperature field during cladding,temperature-time history curve of specific nodes,temperature gradient and cooling rate were studied.It is found that the temperature of the sampling point increases proportionally with the increase of laser power.The smaller the radius of the spot,the slower the scanning speed and the higher the temperature.In the cladding layer,the maximum temperature of the intermediate node is lower than that of the end node,which is called "end effect".Then,based on the finite element simulation of temperature field in laser cladding process,thermal stress analysis is carried out.It is found that the tensile stress will eventually occur in the cladding layer during the cladding process.In each direction,the tensile stress of the cladding joint is different,and the maximum tensile stress is along the Y axis(perpendicular to the direction of the cladding layer).The maximum stress is in the Y-axis direction,while the minimum stress is in the X-axis direction(laser scanning direction).Finally,by analyzing the morphology and size of the high temperature alloyGH864 cladding layer,we can know the relationship between the growth morphology of the cladding layer and the temperature gradient and cooling rate at different positions of the cladding layer,and verify the reliability of temperature field simulation.The morphologies of octahedral and dendritic NbC particles obtained by laser cladding experiments under SEM were analyzed,and the effects of temperature gradient and cooling rate on the morphologies of in-situ synthesized reinforced phase were revealed.According to the simulation results,the experimental results are in good agreement with the corresponding solidification theory.