摘要
对316L不锈钢在激光快速成形过程中的凝固行为和组织形成进行了考察．结果表明,成形件呈现全γ奥氏体结构, γ奥氏体从基体外延生长成柱状枝晶,并显示较强的晶体取向性,其<100>晶向基本平行沉积方向,仅在顶部出现一薄层转向枝晶层,而在成形件中出现的层带结构并未影响不同熔覆沉积层之间组织生长和取向的连续性．采用最高界面生长温度判据对激光快速成形中的相形成规律进行了分析,并结合平界面稳定性分析、枝晶生长理论和柱状晶／等轴晶转变模型讨论了成形件中的层带形成及外延柱状晶生长特性．
The solidification behavior and the morphological evolution of 316L stainless steel during laser rapid forming （LRF） were investigated. It was found that, the LRF sample is completely consisted of columnar γ austenitic dendrites which grew epitaxially from the substrate, and have the （100） direction approximately parallel to the deposition direction, but in a thin layer at the top of the LRF sample the dendrites grew along the laser scanning direction. Band-like structures between deposited layers existed in the sample, which don＇t effect the growth continuity of the columnar dendrites. The solidification pattern and phase selection were predicted by the microstructure selection models based on the maximum interface temperature criterion. The formation of the band-like structure and the epitaxial growth characteristic are also explained by the criteria for planar interface instability and dendritic growth theory and the columnar to equiaxed transition model.
出处
《金属学报》
SCIE
EI
CAS
CSCD
北大核心
2006年第4期361-368,共8页
Acta Metallurgica Sinica
基金
国家自然科学基金项目50331010
50201012和50405038资助
关键词
激光快速成形
不锈钢
凝固
组织
laser rapid forming （LRF）, stainless steel, solidification, microstructure
