摘要
采用YLS4000光纤激光器对2 mm厚LZ91镁-锂合金板材进行了焊接,并对焊接件进行了250℃1 h退火,采用OM、XRD、SEM观察了焊缝的显微组织,通过拉伸试验、硬度测试分析了焊接件的力学性能。结果表明,在合适的焊接工艺参数下,能获得成型良好的焊接接头;焊缝由等轴晶区、树枝晶区以及热影响区组成,热影响区较窄,α相呈细小的颗粒状和针状分布在β相基体中。树枝晶区的硬度最高,等轴晶区次之,热影响区最小,均高于母材的;焊接件拉伸断裂在熔合线处,抗拉强度为135.8 N/mm2,达到母材的81.2%。退火后焊缝组织全部变成了等轴状,基体中细针状的α相大部分转变成细颗粒状,焊件力学性能得到提高,强度达到母材的95.1%。
The material used in this experiment,2 mm thick welding consumables of LZ91 magnesium lithium alloy, is welded by the YLS4000 laser-welding machine and anneal at 250℃ 1 h afterwards. The performance of wedding fabrication and microscopic structure of welded joint are studied by utilizing OM, XRD and SEM, and the mechanical property of wel- ded joint is analyzed through tensile experiment and Vickers hardness test. The result shows that a good molding welded joint that consists of equiaxed crystal area, branch crystal area and a narrow heat affected zone can be obtained by adopting the technological parameter of this experiment. Tiny Alpha phases of welded joint distribute in granular and needle-like forms in Beta phase matrix. The Vickers hardness value of branch crystal area is the highest, the next is equiaxed crystal area, and the heat affected zone is the lowest. While the hardness of the three mentioned areas are all higher than that of the parent metal. The tensile failure of welded joint locates at fusion line,with tensile strength of 135：8 N/mm2 which is 81.2 per-cent of that of the parent metal. After annealing at 250℃ 1 h, microscopic structure of welded joint turns into equiaxed crystal of different sizes, and fine acicular-shaped Alpha phase turns into fine-grained shapes. Mechanical properties are improved and the strength reaches 95.1 percent of that of the parent metal.
出处
《轻合金加工技术》
CAS
北大核心
2016年第8期59-65,共7页
Light Alloy Fabrication Technology
基金
国家自然科学基金资助项目(51371161)
国家国际科技合作专项(2015DFR0020)
郑州市科技创新团队项目(131PCXTD601)
关键词
镁-锂合金
激光焊接
显微组织
力学性能
Mg-Li alloy
laser welding
microstructure
mechanical properties
