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采用300 W YAG激光器对7050铝合金预拉伸板进行激光成形修复实验研究。实验中选用的粉末是AlSi12,通过多道多层激光修复实验,得到了优化的工艺参数。分析了冶金缺陷产生的原因及消除措施,并分析激光修复区的组织形成和分布规律。实验结果表明,修复过程中产生的冶金缺陷主要有界面熔合不良、气孔和液化裂纹。通过对基材表面进行化学处理、优化修复工艺参数、改变粉末状态等方法获得了修复区内无气孔、裂纹,同时界面熔合良好的修复试样。组织分析结果表明,修复区底部为α-Al固溶体树枝晶和少量的枝晶间Al-Si共晶组织,随着熔覆层数的增加,共晶体积分数不断增加,同时α-Al固溶体树枝晶组织不断细化,并发生柱状晶/等轴晶转变,在修复区顶部获得了完全细化的等轴晶组织。
Experimental Study of Laser Forming Rehension of 7050 Aluminum Alloy by 300 W YAG Laser. The powder used in the experiment is AlSi12, and the optimized process parameters are obtained through multi-channel multilayer laser repair experiments. The causes of metallurgical defects and the elimination measures are analyzed. The formation and distribution of laser repaired zones are also analyzed. The experimental results show that the metallurgical defects in the repairing process mainly include poor interface fusing, fissures and liquefied cracks. Through the chemical treatment of the substrate surface, the optimization of the repair process parameters, change the powder state and other methods to get the repair area without pores, cracks, and the interface fusion good repair samples. The results of microstructure analysis show that the bottom of the repaired area is composed of α-Al solid solution dendrites and a small amount of interdendritic Al-Si eutectic structure. With the increase of the number of cladding layers, the eutectic volume fraction increases continuously. Meanwhile, α-Al solid solution dendrites The crystal structure is continuously refined and the columnar crystal / equiaxed crystal transition occurs, and the completely refined equiaxed crystal structure is obtained at the top of the repair area.