摘要
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。
Laser forming repair pre-tensile 7050 aluminum alloy with AlSi12 powder was studied using 300 W YAG laser. The optimized process parameters were obtained in multi-trace and multi-layer laser repair experiment. The elimination measures of metallurgical defects and the microstructures distribution of repaired zone were analyzed. It is found that the metallurgical defects including illbond, porosities and liquefied cracks can be eliminated through chemical treatment for the substrate surface, optimizing the process parameters and changing the powder condition. The microstructure at the bottom of the repaired zone is composed of the α -Al solid solution dendrite and a small number of Al-Si eutectic. With the increasing of the cladding layers, the eutectic volume fraction increases continuously, the α -Al solid solution dendrite is refined and the transformations from columnar grain to equiaxed grain take place. Finally, the completely refined equiaxed grains are achieved at the top of the repaired zone.
出处
《中国激光》
EI
CAS
CSCD
北大核心
2009年第6期1585-1590,共6页
Chinese Journal of Lasers
基金
国家自然科学基金重点项目(50131010)
新世纪优秀人才支持计划(NCET-06-0879)
国家863计划 (2006AA03Z0449)
国家973计划(2007CB613805)资助课题
关键词
激光技术
显微组织
激光成形修复
冶金缺陷
7050铝合金
laser technique
microstructure
laser forming repair
metallurgical defect
7050 aluminum alloy
