316L不锈钢选区激光熔化单道熔池几何尺寸演变规律

Evolution Law of Single Pass Molten Pool Geometry of 316L Stainless Steel in Selective Laser Melting

目的探究激光功率(P)和扫描速度(v)对单熔道熔池几何特征尺寸的影响规律,以及P–v组合工艺参数对熔池从成形到稳定状态经历的扫描距离的影响规律。方法以316L为材料,通过单熔道数值仿真分析,建立P–v变量与研究目标之间的影响关系。结果不同P–v参数组合对熔池几何尺寸的影响规律明显,熔池几何参数达到稳定状态需要经历一定的激光扫描距离(小于1 mm)。随着激光功率增大,熔池长度达到稳定状态所经历的激光扫描距离随之增大,而熔池深度尺寸随之减小。扫描速度增大到400 mm/s时,熔池达到稳定经历的扫描长度缩短了6.7%,扫描速度对熔池稳定性的影响效果不显著。结论在SLM单道成形过程中,激光功率、扫描速度越大,成形熔池平均长度尺寸也越大;激光功率越大、扫描速度越小,成形熔池深度及平均宽度越大。模拟试验获得重熔效果较好的P–v参数组合为P=200W、v=800mm/s,重熔率达到94%。在熔池成形过程中,激光功率对熔池稳定性的影响起主导作用。为了减少成形件的边界翘曲,在打印试件初始成形阶段应在合理激光功率范围内选择较高的激光功率。

The work aims to explore the effect law of laser power(P)and scanning speed(v)on the geometric feature size of single pass molten pool and P-v combination parameters on the scanning distance of molten pool from forming to stable state.With 316L as the material,the effect relationship between P-v variable and research target was established through numerical simulation analysis of single pass.Different P-v combination parameters had obvious effects on geometry of molten pool and it took a certain laser scanning distance for the geometric parameters of the molten pool to reach a stable state.With the increase of laser power,the laser scanning distance for the molten pool length to reach a stable state increased,while the depth of the molten pool decreased,the scanning speed increased by 400 mm/s,and the scanning length for the molten pool to reach a stable state shortened by 6.7%.The effect of the scanning speed on the stability of the molten pool was not significant.In the single pass forming process by SLM,the larger the laser power and scanning speed,the larger the average length of the forming molten pool.The higher the laser power and the lower the scanning speed,the greater the depth and average width of the forming molten pool.The combination of P-v parameters with good remelting effect obtained from the simulation test is p=200 W,v=800 mm/s,and remelting rate of 94%.In the forming process of molten pool,laser power plays a leading role in the stability of molten pool.In order to reduce the boundary warpage of the formed part,a higher laser power should be selected within a reasonable range in the initial forming stage of the printed specimen.