采用光纤激光器对ZL114A铸造铝合金进行激光沉积修复实验研究。修复区与基材形成良好的冶金结合。受温度梯度与凝固速度控制, 由修复区底部到沉积层表面, 显微组织呈现由柱状树枝晶向等轴晶的转变。拉伸试验结果表明: 激光沉积修复样品具有良好的拉伸性能, 修复区的抗拉强度达到了铸件标准的87.5%, 断后伸长率远高于铸件标准。ZL114A合金基体的断裂机制为脆性断裂, 而修复区为韧性断裂。激光沉积修复样品的残余应力峰值出现在基材与修复区结合处, 经去应力热处理退火后, 残余应力略有消减, 最大值降幅为10%~23%。

ZL114A casting aluminum alloy was repaired by laser deposition repair (LDR) using a fiber laser. Morphology analysis showed that the repaired region and the substrate form a good metallurgical combination. Under the control of temperature gradients and solidification rate, the microstructure of laser deposition layer transformed from columnar dendrites at the bottom of laser deposition layer into isometric crystal at the top of the last deposition layer. Tensile tests showed that laser deposition sample exhibited a superior tensile property, the tensile strength of the repaired region reaches 87.5% of Al alloy casting standard, and the elongation is much higher than that of Al alloy casting standard. Fracture analysis showed that the fracture mechanism of ZL114A casting aluminum alloy is brittle fracture, but the fracture mechanism of the repair zone is toughness fracture. Residual stress analysis showed that there exists the stress concentration issue, and the peak of residual stress locates in the joint between the substrate and the repaired region. After stress relief annealing, the residual stress of laser deposition samples decline by 10-23 percent.