中国激光, 2015, 42 (2): 0203002, 网络出版: 2015-01-09
ZM5镁合金薄壁铸件光纤激光补焊工艺与组织性能研究
Research on Microstructure and Properties of Fiber Laser Repairing ZM5 Magnesium Alloy Thin-Walled Casting
激光技术 ZM5镁合金 光纤激光 激光补焊 微观组织 力学性能 laser technique ZM5 magnesium alloy fiber laser laser welding microstructure properties
摘要
采用光纤激光对ZM5镁合金薄壁铸件进行补焊研究,以焊道稀释率和表面交角进行工艺评价,通过扫描电子显微镜(SEM)和X 射线衍射(XRD)表征了样品的显微组织、相组成,并作了拉伸试验分析。结果表明,补焊焊缝稀释率和焊道表面交角成线性相关变化,补焊层由细小的等轴树枝晶组成,平均晶粒直径为15~20 μm,约为ZM5 母材的1/4;补焊层基体组织为α -Mg 相,晶界析出Mg-Al共晶相,其中β -Mg17Al12以连续网状或不规则的点状析出;补焊层抗拉强度和延伸率优于母材,补焊层拉伸断口为准解理断裂,断口有少量韧窝,而经均匀化热处理的母材断口为脆性断裂的解理断口。组织表征和性能试验表明,光纤激光可实现ZM5 镁合金铸件的缺陷补焊,且在工艺上具有很好的适应性。
Abstract
In order to repair thin-walled castings of ZM5 magnesium alloy, the parameters for fiber laser welding are determined by dilution rate and weld-surface angle. Scanning electron microscope (SEM) and X-ray diffraction (XRD) are adopted for microstructure observation and analysis of chemical composition while tensile tests are carried out for evaluation of mechanical properties. It′s demonstrated that the relationship between dilution rate and weld-surface angle is linear dependence. The fiber laser welding layer consists of tiny equiaxed dendrites with the average grain diameter of 15 to 20 μm which is 1/4 of ZM5 base. The base structure of welding layer is α - Mg phase, and the eutectic Mg-Al phase, β - Mg17Al12 mainly, is even dispersed along the grain boundary of welding layer. Shown in tensile tests, quasi-cleavage fracture occurred in fiber laser welding layer, which achieves higher strength and toughness than those of the brittle-fractured base metal. Thus thin-walled castings of ZM5 magnesium alloy are so well repaired by fiber laser that production quality and efficiency are greatly improved.
陈宏, 李铸国, 姚成武, 吴毅雄. ZM5镁合金薄壁铸件光纤激光补焊工艺与组织性能研究[J]. 中国激光, 2015, 42(2): 0203002. Chen Hong, Li Zhuguo, Yao Chengwu, Wu Yixiong. Research on Microstructure and Properties of Fiber Laser Repairing ZM5 Magnesium Alloy Thin-Walled Casting[J]. Chinese Journal of Lasers, 2015, 42(2): 0203002.