WE43镁合金SLM成形数值模拟及试验验证

Numerical Simulation and Experimental Validation of SLM Forming of WE43 Rare Earth Magnesium Alloy

目的研究WE43镁合金激光选区熔化(SLM)成形过程、成形后变形及应力分布的变化规律,得到SLM态WE43常温拉伸力学模型。方法采用SLM方法制备了WE43镁合金悬臂梁及拉伸试样,通过对比悬臂梁局部切割翘曲试验结果与数值模拟结果,得到WE43镁合金固有应变模型,实现WE43镁合金SLM成形过程的模拟及变形预测;对SLM态WE43镁合金开展拉伸试验,使用金相显微镜及扫描电镜进行微观组织及断口形貌观察;采用Normalized Cockcroft&Latham模型对拉伸试验进行模拟,实现SLM态WE43常温拉伸过程分析。结论常温SLM态WE43的抗拉强度为313 MPa,屈服强度为236 MPa,延伸率为7.6%,试样中存在不规则孔洞缺陷;在SLM成形过程中,WE43镁合金固有应变值exx、eyy、ezz分别为−0.0025、−0.0025、−0.0115,悬臂梁最大翘曲高度为1.99 mm,模拟结果显示未切割悬臂梁最大等效应力为12.3 MPa;当NC&L断裂准则临界损伤值为0.1时,WE43常温拉伸过程模拟结果与试验结果最为接近,预测准确率为93%。

The work aims to get the variation of deformation field and stress distribution during and after the forming process of WE43 magnesium alloy selective laser melting(SLM),and to get the room temperature tensile mechanics model of WE43 in SLM state.The cantilever beam and tensile specimen of WE43 magnesium alloy were prepared by SLM method,and the intrinsic strain model of WE43 magnesium alloy was obtained by matching the height of cantilever buckling after local cutting of cantilever beam with the numerical simulation value,to realize the simulation and deformation prediction of SLM forming process of WE43 magnesium alloy.Tensile test was carried out on WE43 magnesium alloy in SLM state,and microstructure and fracture morphology were observed by metallurgical microscope and scanning electron microscope.The tensile test was simulated by the Normalized Cockcroft&Latham damage model to analyze the tensile process of the SLM state WE43 at room temperature.The tensile strength of WE43 in SLM state at room temperature is 313 MPa,yield strength is 236 MPa,elongation is 7.6%,and there are defects such as irregular holes in the specimen.The intrinsic strain values of WE43 magnesium alloy in the SLM forming process are−0.0025,−0.0025 and−0.0115 for the values of exx,eyy and ezz respectively.The simulation results show that the maximal equivalent force in the forming process of cantilever beam is 12.3 MPa.and the maximum buckling height is 1.99 mm.When the critical damage value of NC&L is 0.1,the simulation of the room temperature tensile process of WE43 is closest to the tensile test results,with a prediction accuracy of 93%.