基于温度场模拟的镁合金SLM元素烧损行为

SLM element burning behavior of magnesium alloy based on temperature field simulation

镁合金在选区激光熔融(SLM)成型过程中,由于Mg元素蒸汽压较高,熔沸点较低,在高能量激光束作用下极易出现烧损并产生大量烟尘。为有效抑制镁合金SLM成型过程中的元素烧损,提出了烧损速率与工艺参数关系建模方法,首先通过SLM温度场仿真建立工艺参数与温度之间的关系模型,然后结合气体动力学与热力学理论建立元素烧损速率与温度之间的解析关系模型,最终建立工艺参数与元素烧损速率之间的关系模型。研究发现在激光功率为70~90W、扫描速度为300~500mm/s时烧损速率较小。对该窗口进行SLM成型实验验证,发现在此窗口下烟尘量明显减少,成型件性能提高,且在激光功率为85 W、扫描速度为400mm/s时试件的平均抗拉强度为324.1 MPa,延伸率为10.12%。

Due to the high vapor pressure and low melting boiling point of the Mg element in the Selective Laser Melting(SLM)forming process,it is easy to burn and produce a large amount of smoke under the action of high energy laser.To restrain element burning loss in SLM forming of the magnesium alloy,a method for modeling the relationship between the burning loss rate and the process parameters was proposed.First,by simulating the SLM temperature field,the relationship between process parameters and temperature model was established.Second,based on the theory of gas dynamics and thermodynamics,an analytic relation model between the burning rate and temperature was built.Finally,the relationship model between process parameters and element loss rate is developed.It was found that the burning rate is small when the laser power was 70-90 W and the scanning speed was 300-500 mm/s.SLM molding experiments were carried out to verify the window,and it was found that in this window,the amount of smoke was significantly reduced,and the performance of the molds was improved.When the laser power was 85 W and the scanning speed was 400 mm/s,the average tensile strength of the specimen was 324.1 MPa,and the elongation was 10.12%.