选区激光熔化316L大层厚成形工艺及性能研究

Study on the Forming Process and Performance of 316L High Layer Thickness by Selective Laser Melting

针对316L金属粉末进行选区激光熔化(SLM)成形工艺研究,以获得高致密度块体。为了提高SLM成形效率,对150μm大层厚成形过程进行了研究。通过改变曝光时间,块体试样致密度可达到99.99%,成形率可达到8.1mm3/s,约为以往研究中成形率的2~8倍。此外,还发现三种典型缺陷,熔池间未熔合缺陷,熔池内部微孔缺陷和无规律分布的球化缺陷。熔池间未熔合缺陷可通过调整工艺参数予以消除,微孔和球化缺陷对致密度的影响较小,但通过调整工艺参数,很难将其完全消除。平均屈服强度、抗拉强度和延伸率分别为525MPa、625MPa和40.1%,这与以往小层厚成形的拉伸性能没有明显差异,这是由于不同层厚都具有类似的冶金结合和微观结构。

The forming process of selective laser melting（SLM）of 316 Lis studied to obtain high density blocks.In order to improve the forming efficiency of SLM,the forming process of 150μm high layer thickness is studied.The density of block sample can reach 99.99%,the forming rate can reach 8.1 mm3/s,which is about 2~8 times of the forming rate in the previous research.In addition,three typical defects are also observed：the un-melted defects between melting pool,micro-pores defects within the pool and irregular distribution of spherical defects.The un-melted defects between the melting pool can be eliminated by adjusting process parameters,micro-pores and spherical defects have little effect on density,but it is difficult to eliminated them completely by adjusting process parameters.The average yield strength,tensile strength and elongation are 525 MPa,625 MPa,and 40.1%,respectively,which are not significantly different from the tensile properties of the former small thickness because of similar metallurgical bonding and microstructure.