Numerical Simulation Of The Temperature Field And Stress Field For Plasma Powder Deposition Manufacturing Process

Plasma Powder Deposition Manufacturing (PPDM) is a metal surfacing technology, which utilizes the plasma arc to make powder melt and shaped a substrate along the stated path by a program, by the stacked content theory. So this technology is suitable to the rapid manufacturing of high-melting point alloys, and has received much attention in the world. The key of this technology is the formability and the control of the thermal stress. And these are associated with the temperature field and stress field. It's important to know how the deposition process parameters affect the temperature and stress field systematically and how they act on the forming properties, and the quality can be researched ulteriorly. Considering the process characteristics of PPDM, it is made to simulate the process of high melting-point alloy deposition manufacturing on the basis of the heat transfer theory and the thermal elastic-plasticity theory. The focus of the research is the self-activation mesh model based on the forming theories and the numerical model of the temperature field and the stress field under the condition of a high-energy moving heat source. Firstly, considering the influence of surface tension, to establish the deposition topography curve equation. Secondly, to utilize ANSYS to select coupling elements and mesh them individually, to simulate the subsequence of element growing on this finite element model, and to load thermal constraint according to the energy characteristics. At last an APDL program has been developed to simulate the temperature field and the stress field of PPDM. Making the example of nickel-base high-melting point alloy, and considering the Gauss model for energy distribution of the plasma arc, different forming processes were simulated. The simulation results show that the temperature field changed rapidly with time and space in the PPDM process. With the deposition height increased, the temperature field tended to uniform. The maximum residual stress existed in the corner of joints, and the residual stress field by water quenching was much better than by natural cooling. In the latter condition the stress at the corner was tensile, and the corner would be prone to micro-cracks. But in the former condition the stress was compressive. And the higher scanning velocity in the forming process would make the stress field uniform, and could reduce the thermal stress. Also, the higher initial temperature can reduce the thermal stress. At last an experiment was carried out to measure the temperature field of PPDM and verified the temperature field simulated by the developed software well. The result shows the effectiveness of the simulation model.