摘要
采用激光逐层熔化沉积工艺制备了组织致密、定向性良好的DZ408镍基高温合金单道和多道扫描板状试样,对其沉积态显微组织的定向生长规律及成形机理进行了分析。结果表明,单道板试样表面光洁且形状规则,在沉积方向生成定向性良好的枝晶,而在扫描方向,枝晶受熔池形状影响,生长方向向扫描方向倾斜。多道板试样在垂直于扫描方向处,形成"Z"型组织,而在平行于扫描方向处,由于激光单道扫描结束时间长、冷却周期短,试样边界处沉积层的厚度是内侧沉积层的两倍,且熔池线向下塌陷;金属液由于重力超过表面张力而形成金属液滴,最终在多道板试样表面形成了大量金属瘤。
Plate sample of Ni-based superalloy DZ408, with compact structure and good orientation, was pro- duced by laser melting deposition with single- and multi-channel scanning. Orientation growth law and formatioh mechanism of as-deposited microstructure were analyzed. The results indicate that plate sample prepared by single-channel scanning is of regular shape and polished surface, and well-orientated dendrites form in solidification direction. However in scanning direction,the dendrites tilt towards the scanning direction due to the influence of the shape of molten pool. Z-type microstructure perpendicular to scanning direction is obtained in the plate sample prepared by multi-channel scanning. The thickness of laser single-chan- nel depositing layer parallel to the scanning direction in the sample border is twice as much as that in the sample insider for long ending time of laser single-channel scanning and short cooling time,and its bath line collapses duwn. The gravity of liquid metal is greater than its surface tension, thus the metal droplets are formed and finally,lots of metal tumors appear in the surface of the multi-channel scanned samples.
出处
《稀有金属与硬质合金》
CAS
CSCD
北大核心
2014年第1期46-51,共6页
Rare Metals and Cemented Carbides
关键词
DZ408镍基高温合金
激光熔化沉积
晶体定向生长规律
组织成形机理
Ni-based superalloy DZ408
laser melting deposition
crystal orientation growth law
mechanismof microstructure formation
