摘要
采用不同的工艺参数(激光功率、扫描速度、扫描间隔、铺粉层厚)对304L不锈钢粉末进行了选择性激光熔化(SLM)成形实验。利用密度测试、金相显微镜(OM)、扫描电子显微镜(SEM)对成形件的密度与微观组织进行了分析。结果表明:高的激光功率、低的扫描速度、窄的扫描间隔和低的铺粉层厚有利于成形件的致密化;304L不锈钢粉末SLM成形的致密化过程可用致密化方程表示,随着能量密度的增加,相对密度也随之增加;304L不锈钢的SLM成形过程具有较大的过冷度和冷却速度,热流方向变化复杂,晶粒沿各个方向形核生长,且生长又不断被抑制,从而形成沿各个方向错综排列的、细小的柱状晶和胞状晶组织。
Different technical parameters （laser powder, scan speed, scan interval and layer thickness） were utilized to fabricate 304L stainless parts via selective laser inching （SLM） technology. Density measurement, optical microscope and scan electronic microscope were used to characterize densities and microstructures of formed parts. Results can be listed as follows. A higher laser power, lower scan speed, narrower scan interval and lower layer thickness could induce a better densification. Morever, the final density is also influenced by a laser specific energy density, which results in a better densification when a higher energy density is applied, and this process can be expressed via a densification equation. In SLM process, very high degree of supercooling and cooling velocity occurs, and the heat flow direction varies complexly, leading to restrained crystal growth directions. As a result, the microstrueture of formed parts exhibits columnar crystal and cellular crystal with very fine size and different growth direction.
出处
《应用激光》
CSCD
北大核心
2009年第5期369-373,共5页
Applied Laser
基金
国家863计划资助项目(项目编号:2007AA032115)
粤港关键领域重点突破资助项目(项目编号:20074982120)
