选区激光熔化过程热应力试验研究

Experimental Study on Thermal Stress in the Process of Selective Laser Melting

对316L不锈钢材料选区激光熔化热应力进行研究,搭建实时应力监测平台,探究热应力变化规律、温度与热应力的相关性、SLM成形单层多道和单道多层扫描热应力变化规律,并进一步研究在不同工艺参数下热应力的变化。结果表明,选区激光熔化过程中,热应力的变化有4个阶段——受压、受拉、拉压抵消、拉压平衡,且最终残余应力为拉应力;热应力的变化幅度与扫描速度呈负相关,与激光功率呈正相关,但过小的扫描速度会造成熔覆过程中出现重熔的现象,使残余应力得到释放。

In this paper,selective laser melting thermal stress of 316 L stainless steel materials was studied,and real-time stress monitoring platform was established.The change discipline of thermal stress,correlation between temperature and thermal stress,change discipline of scanning thermal stress of SLM finished single-layer multi-channel and multi-layer single-channel were discussed,and the change of thermal stress under varied craft parameters was further studied.Results show that in the process of selective laser melting,the change of thermal stress includes four stages:press,pull,offsetting of press and pull,balance of pull and press,and the final residual stress is pull stress;the change altitude of thermal stress is negatively correlated with scanning speed,and positively correlated with laser power.However,slow scanning speed led to remelting in the process of melting and made residual stress released.