激光定向凝固参数对熔覆层宏观形貌以及微观组织的影响

摘要

激光定向凝固技术在航空发动机涡轮叶片上大量使用,但激光参数对熔覆层宏观形貌以及微观组织的影响鲜有研究.研究了DZ22择优取向基材上沿基材外延生长的定向凝固熔覆层宏观形貌和微观组织与激光参数之间的规律,发现了参数对熔覆层宏观形貌的影响规律,并找到了最佳的激光熔覆参数.另外,对微观组织分析发现,熔覆层上层以及两侧均为等轴晶或杂晶,其中,电流和脉宽与一次枝晶间距和转向枝晶区高度成正比,扫描速度与一次枝晶间距和转向枝晶区成反比,而且深宽比大的熔覆层柱状晶区域占比大.%The laser directional solidification technology is much used in turbine blade of aero engine.However,the effect of laser directional solidification parameters on macroscopic and microstructure of cladding layer is littled studied.The macro-morphology and microstructure of the directional solidification cladding layer epitaxial growth along the substrate of DZ22,and the effect of laser process parameters are studied.The influence of the parameters on the macroscopic morpholo-gy of the cladding layer and the best laser cladding parameters are found.In addition,the microstructure analysis shows that the upper cladding layer and the two sides are equiaxed or mixed crystal.The current and pulse width are proportional to the dendrite spacing and the height of the dendrite zone.The scanning speed is inversely proportional to the primary dendrite spacing and turning dendrite zone.And the larger the aspect ratio is,the more area the columnar crystal covers.