摘要
采用"生死单元"技术模拟了激光金属直接成形DZ125L单层单道和单层两道试样时扫描单元内部温度场的分布情况,分析了熔池温度梯度的分布与试样内部金相组织演变的关系并进行了实验验证。结果表明,成形单层单道试样时,柱状晶能够从基材连续向上生长,熔池中间部位柱状晶连续生长得最高,并且熔池顶部容易形成等轴晶;成形单层两道试样时,扫描方式与搭接率对温度场分布及金相组织的转变影响较大,往复扫描方式下搭接区容易产生转向枝晶,搭接率过小会严重影响两道搭接处柱状晶的连续生长。模拟结果和实验结果吻合得较好。
The effect of scanning methods and overlap rate on the temperature field and microstructure evolution of DZ125L super-alloy elementary unit in laser metal direct forming is investigated numerically and experimentally. The results show that temperature field in the molten pool leads to the epitaxial growth of columnar crystal from the substrate; the columnar crystal grows highest at the center position; it is multi-directional crystal at the high part. For double-track forming, the temperature field and the change of microstructure in the overlap zone are strongly influenced by the scanning method and the overlap rate; the back-and-forth scanning method easily leads to the change of the solidified direction; the epitaxial growth of columnar crystal between cladding tracks is obtained when the overlap rate is big enough. The results of calculation agree well with that of experiment.
出处
《中国激光》
EI
CAS
CSCD
北大核心
2013年第6期191-197,共7页
Chinese Journal of Lasers
基金
国家973计划(2007CB707704)
国家自然科学基金(51005177
51275392)资助课题
关键词
激光技术
激光金属直接成形
DZ125L高温合金
温度场
柱状晶
laser technique
laser metal direct forming
DZ125L Ni-based super alloy
temperature field
columnar crystal
