3D Finite Element Simulation Of The Temperature Field And Experiment Study On Direct Metal Laser Sintering

Direct Metal Laser Sintering is an important branch of Selective Laser Sintering technology, it improves the product flexibility unlimitedly for need no any dies & tools, un-restricted by part geometry shape, higher material utilization, shorter life cycle and so on, and it becomes an important development direction of advanced manufacturing increasingly.At the present time, balling effect and warpage deformation are the two important problems need to be solved in the DMLS field, the laser moving thermal resource of concentrating input is bound to make the temperature field distribution instability and produce thermal stress, this is the ultimate reason of the sintered part quantity problem.Whether Metal part form smoothly or not, the microstructure and performance are fine or not, all depend on the choice of processing parameters. So, if want to choose the appropriate processing parameter and get fine sintered part with regular shape, high densification and fine performance , the evolution process of the temperature fields time-depended are needed to acquire.This thesis make a deep research on DMLS temperature field simulation and related experiment as follows:First, The present status of development and trend of DMLS process and temperature field both at home and abroad are analysied, the key problem which affects sintered quantity and the deficiency of the temperature fields are presented.Second, the technique of ANSYS birth/ death for element is introduced in the DMLS multi-layers sintering simulation for the first time. It carrises out the process of material dynamic addition. At the same time, The problem of the moving and load of laser thermal resource, the treatment of the material nonlinear,phase-change latent heat and the circular beam and so on are resolved.Third, heat conduction, heat convection and material high linear are considered comprehensively, the 3D FE model of the temperature field which matched with DMLS process has been established based on ANSYS software, and the simulation was conducted by using Ni-based alloy power. The heating-cooling process of laser molten pool, the process of inter-sintering tracks and inter-layers, the effect process on temperature field of different process parameters are analysed and suitable process parameters is selected.In the last, sintering experiment is carried out based on the Ni -based alloy powder and the research tools are large power laser device, JXA-840A SEM, HVS-1000 micro-hardness instrument. The effect on the quality of sintering line and balling effect of laser power and scan speed are analysed, and got the multi-layers sintered part by the optimized parameters. At last, the sintering width and depth has been measured , the micro-structure has been observed. The simulation results are contrasted with experiment results and the simulation results agree with the experimental results well.