Numerical Simulation Of Residual Stress In Laser Cladding

Laser cladding is an advanced technology by which a powdered material with completely different Composition and Property can be melted and consolidated onto matrix surface then formed metallurgical bonding with the matrix.It is widely used in materials Preparation, metal parts rapid direct manufacturing and failure metal parts Green Remanufacturing areas,etc.In the Laser cladding process,material experienced rapid melting and rapid solidification process,accompanied complex thermal physical process and microstructure generation process.As a result of heat input effect during laser cladding process,Residual Stress were generated inevitably.While residual stress will seriously affect workpiece's mechanical performance and use life.Meanwhile the stress evolution and distribution is difficult to measure by means of test.Therefore,Numerical simulation of temperature and stress field is a effective method to access temperature information and stress strain information.This article use ANSYS software and MSC.Marc software respectively,adopt sequential coupling method and direct coupling method to establish the stress field finite element model of synchronous Powder feeding Laser Cladding process. The simulation was carried out.The major content as follows:Use ANSYS Parametric Design Language APDL, established synchronous Powder feeding Laser Cladding finite element model.Defined the boundary conditions, latent heat and other thermal parameters changing with temperature.Adopt ANSYS Alive&Death element to simulation powder fell into melting pool process.Simulation first conducted a nonlinear transient thermal conduction analysis,then obtained temperature field distribution of laser cladding process.Then based on the temperature field, through element conversion,convert the thermal analysis model into structure analysis model. Then conduct a quasi-steady-state analysis of elastic-plastic mechanics, and obtained the residual stress distribution on the workpiece.And the Simulation results of Stress distribution were analyzed.Use MSC.Marc nonlinear FEM Universal analysis software established synchronous Powder feeding Laser Cladding thermodynamic coupling numerical model.Adopted thermo-elasto-plastic direct coupling Finite Element Method,in considering temperature dependent material thermal-physical parameters,stress evolution and stress distribution during laser cladding and the following cooling process were analyzed.The stress distribution along the path on the surface of the workpiece and the path along the depth direction were investigated respectively.Results show that there was residual tensile stress in the cladding layer.and the longitudinal tensile stress was much larger than the transverse tensile stress. The longitudinal residual tensile stress is the main reason for Cladding cracking.In cladding layer, VonMises stress close to the size of the material yield stress.Established the Temperature and Stress field model of laser cladding under different scanning speed,simulated and obtained the temperature field and stress distribution under different scanning speeds.Results showed that With scanning speed increases, the equivalent VonMises peak stress on the cladding layer surface also increased.