激光选区熔化致密度预测模型建立与工艺验证

致密度是评价增材制造成型件性能的重要参数之一,而高致密度成型件对应的工艺参数需要大量实验研究获得。针对该问题,本文建立了基于工艺参数的熔池致密度预测模型,能够有效地预测熔合不良引起的孔隙,进而为激光选区熔化工艺参数的选择和优化提供更多的参考。模型采用有限元分析和数值计算软件获得熔池尺寸以及模拟多层多道次的熔池拼接形貌,并预测工艺参数对应的致密度。同时在熔池预测模型中引入了波动系数、偏转角度以及层间扫描转角,以此兼顾熔池尺寸波动、熔池倾斜以及层间扫描转角对熔池模拟结果的影响。最终通过HR-2不锈钢选区激光熔化实验对预测模型的可行性进行验证。结果表明,模型预测结果与成型件熔池实验结果吻合较好,致密度预测结果与实测偏差在2%以内。

Laser selective melting density prediction model and experimental verification

Relative density is one of the important parameters to evaluate the performance of additive manufacturing components, but the corresponding process parameters of high relative density components need a large number of experimental studies. This paper has established a prediction model of the relative density based on the process parameters, which can effectively predict the pores caused by lack of fusion, and provide more reference for the selection and optimization of laser selective melting process parameters. The finite element analysis and numerical calculation software were used to obtain the sizes of the melting pool and simulate the splicing morphology of the melting pool with multiple layers and traces, and predict the corresponding density of the process parameters.At the same time, the fluctuation coefficient, the deflection Angle and the angle of scan vectors rotation between layers are introduced into the prediction model of melting pool to account for the influence of the size fluctuation of the melting pool, the inclination of the melting pool, and the angle of scan vectors rotation between layers on the simulation results of the molten pool. Finally, the feasibility of the prediction model has been confirmed by the selective laser melting experiments of HR-2 stainless steel. The results suggest that the predicted results of the model are in good agreement with the experimental results of the melting pool of the samples, and the deviation between the predicted results of the relative density and the experimental results is within 2%.