激光选区熔化关键工艺参数对热物理过程的影响

Selective laser melting (SLM) is of vital value in the manufacturing industry which melt powder material, such as metal powder, layer-by-layer by using laser beam. Nevertheless, the thermal physical phenomena and the influence of process parameters on the thermal physical process need to be further studied. A multi-track numerical model, considering the phase change and irreversible powder-to-solid transition, was established to simulate the SLM of 316L stainless steel. The effects of laser power, scan speed and effective laser beam diameter on the temperature field, melting time, cooling rate and melt pool dimension was studied. Experiment was conducted to verify the reliability of numerical simulation results. The results indicated that the melting time is easily affected by laser power and scan speed, while the maximum cooling rate is more sensitive to effective laser beam diameter. With relative low laser power or high scan speed, the melt pool dimension is comparatively small, and easy to form cave like defects. The effective laser beam diameter has a small effect on the melt pool dimension. The stability of melt pool firstly has no certain change tendency and then increases with the increasing laser power. With the increase of scan speed, the stability of melt pool decreases continuously. The effect of effective laser beam diameter on the stability of melt pool is uncertain. The numerical simulation results are approximately in accordance with the experimental results and provide guides to tuning and optimizing the process parameters in SLM.