文档介绍：华中科技大学
硕士学位论文
选择性激光熔化成形及热等静压后处理微观研究
姓名:王志刚
申请学位级别:硕士
专业:材料加工工程
指导教师:史玉升
2011-01-11
华中科技大学硕士学位论文
摘要
选择性激光熔化成形(Selective Laser Melting,SLM)技术作为一种新型的快
速成形技术在缩短零件研发周期,直接制造高性能复杂零部件有很大的优势。国内
外已经对其原理做了一定的研究,但是 SLM 制件仍存在诸多缺陷,性能不高,限
制了其广泛应用。
本文以镍及镍基高温合金 GH4169、AISI316L 不锈钢为代表材料,通过研究表
面形貌,金相组织、显微硬度,相对密度等对 SLM 成形前的准备工作提高 SLM 成
形质量、调整工艺参数以提高其制件性能、通过热等静压(hot isostatic pressing,
HIP)对 SLM 制件后处理以提高其性能等方面进形了研究。
研究结果表明:(1)选用合适的粉末、基板、保护气并对其进行前处理会提高
SLM 成形质量;(2)激光功率越高扫描线宽越大;扫描速度越低扫描线宽越大;铺
粉层厚越大,扫描线球化趋势越明显,零件相对密度越低;保护气氛中氧含量越多,
扫描球化现象越明显;扫描搭接率适中(40%~60%)时面扫描球化现象不明显,表
面精度越好。(3)SLM 制件经过 HIP 后,真空裂纹完全愈合,试样中不规则孔体
积缩小,且形状变为球形或者近球形。对于层厚较小,层与层之间粘结紧密,相对
密度较高的零件 HIP 后晶粒更粗大;层厚较大,层间存在少许粘结不良,但孔洞大
部为闭合孔,HIP 后晶粒细小且沿 SLM 加工层间分布。SLM 制件经过 HIP 后,相
对密度都有一定的提升,尤其是对于闭合孔较多的制件中相对密度提升很大;而对
于大部为通孔的零件,高压气体可以进入到孔隙中,相对密度提升有限;HIP 后样
品中仍然存在机械性能的各向异性,显微硬度与材料距离表面的距离关系不大。
通过本文的研究结果,可以对 SLM 成形前、成形中、成形后提升制件性能进
行指导。

关键词:选择性激光熔化;热等静压;AISI316L 不锈钢;镍基高温合金;后处理
I
华中科技大学硕士学位论文
Abstract
Selective laser melting (SLM) is a novel rapid prototyping technology which has
many advantages in shortening developing circle and fabricating metal parts with high
quality plicated shape directly. Researchers at home and abroad have studied its
mechanism, but SLM parts have many problem resulting in poor property, which restricts
their application.
Taking Ni-based high-temperature alloy GH4169 and AISI316L stainless steel as
the materials, preparation work, SLM parameters and hot isostatic pressing(HIP)
post-treatment were investigated to improve the properties of SLM part by studying
surface topography, fine texture, micro-hardness and relative density of parts.
The results show that: (1) Selecting proper powder, base plate and protecting gas
and pre-treating them properly can promote the property of SLM parts. (2) The higher
laser power, the bigger of scanning track width; the thicker of layer, the more likely
balling phenomenon appears, and the lower of the final p