工艺参数对选区激光熔化316L不锈钢缺陷的影响

Effect of Process Parameters on Defect in Selective Laser Melting of 316L Stainless Steel

通过试验观察和数值模拟研究了关键工艺参数(激光功率、扫描速度和激光能量密度)对选区激光熔化316L不锈钢样缺陷的影响,结果表明,孔隙是造成致密度降低的最主要原因。不同类型孔隙的产生与工艺参数特别是激光能量密度密切相关。激光能量输入不足(E<52.778 J/mm3),特别是熔池宽度不够是造成未熔合孔隙的关键原因。激光能量输入过高(E≥93.056 J/mm3)时,熔池温度过高和尺寸过深,是导致匙孔形成的重要因素。而气孔很难完全消除,但合理控制避免过高激光能量输入有利于降低气孔尺寸。通过合理调整工艺参数,致密度可以达到99.62%。

The effects of key process parameters(laser power,scanning speed,and laser energy density)on the defects of 316L stainless steel samples are studied by experimental observation and numerical simulation.The results show that porosity is the main reason for the decrease in density.The generation of different types of pores is closely related to the process parameters,especially the laser energy density.Insufficient laser energy input(E<52.778 J/mm^(3)),especially insufficient molten pool width,is the key cause of unfused porosity.The formation of keyhole is mainly caused by high temperature and deep size of molten pool due to high laser energy input(E≥93.056 J/mm^(3)).It is difficult to eliminate stomata completely,but reasonable control to avoid excessive laser energy input is beneficial to reduce stomata size.By adjusting the process parameters reasonably,the density can reach 99.62%.