单晶高温合金V槽的激光修复工艺研究

Laser Repairing Process of V-Groove in Single-Crystal Superalloy

研究了单晶高温合金的修复工艺对枝晶生长的影响,分析了不同底角V形槽对激光修复枝晶生长的影响。通过在DD5试样上进行激光熔覆来确定合适的工艺参数,发现减小热输入有利于扩大定向枝晶区域。DD5的搭接实验结果表明30%的搭接率有利于减小搭接区域的杂晶。选用合适的工艺参数对DD6试样的不同底角V槽进行修复。结果表明,V形槽底角在60°-120°的范围内变化时,底部枝晶生长方向变化不大,但侧壁附近杂晶会随着熔池温度的梯度方向与最优生长方向夹角的增大而减小。当V槽底角为120°时,侧壁区域不产生杂晶。

The effect of laser repairing process of single-crystal superalloy on the dendrites growth,and the effect of bottom angle of V-groove on the dendrites growth are analyzed.The proper process is determined through laser cladding on the DD5 sample,and it is revealed that the decrease of heat input is beneficial to broaden the zone of directional dendrites.By overlapping experiment on the DD5 sample,it is found that the overlapping rate of 30%benefits the consistency of the dendrites growth in cladding region.With appropriate process parameters,V-grooves of different bottom angles in the DD6 sample are repaired.The results show that changes in the bottom angle of the V-groove from 60°to 120°have little effect on the dendrites growth direction at the bottom.The number of stray grains near the side wall decreases as the angle between the direction of molten pool temperature gradient and the optimal growth direction increases.The stray grains are eliminated in the region of side wall when the bottom angle is 120°.