激光熔覆修复定向凝固镍基高温合金及其拉伸性能

高Al、Ti含量的定向凝固镍基高温合金在传统的修复过程中由于较大的热输入，存在严重的热裂倾向。利用激光热量集中、能量输入小的特点，可以有效控制修复过程中的热输入，从而减小铸造基体的晶界液化和开裂倾向。在优选参数下，可以获得无裂纹的修复组织，并可实现定向凝固组织的连续生长。对修复组织进行热处理，结果表明热处理过程不会促使裂纹产生，也不会影响熔覆层组织的定向凝固特征，但对于其内部γ′相的析出行为及形貌有较大影响，从而影响了沉积层的力学性能。对沉积层的拉伸性能测试表明，无论在常温还是高温(900 ℃)下，沉积层的拉伸性能都达到了铸造基体拉伸性能的80%以上，而且均为塑性断裂，一定程度上满足了实际修复需求。

Laser Cladding Repairing of Directionally Solidified Ni-Base Superalloy and Its Tensile Property

Directionally solidified Ni-base superalloys with high volume content of Al, Ti are considered unrepairable by traditional welding methods due to its high crack susceptivity to heat input. By strictly controlling the laser parameters, however, sound deposition layers were achieved free of cracks. It was also characterized by directional solidification which was not affected by heat treatment process. Large amounts of secondary γ′ particles were precipitated during heat treatment which greatly influenced the mechanical performance of the deposited layers. The tensile tests both of room temperature and 900 ℃ indicated that the tensile strength of the deposition layers after heat treatment can reach 80% of the base material and the fracture were ductile. The mechanical performance of the deposition layers can meet practical need of industrial use.