Dissimilar joining of AZ31B Mg alloy to Ni-coated Ti-6Al-4V by laser heat-conduction welding process
Dissimilar joining of AZ31B Mg alloy to Ni-coated Ti-6Al-4V by laser heat-conduction welding process
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DOI：
10.1016/j.jmapro.2018.05.037
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发表时间：
2018-08
影响因子：
6.2
通讯作者：
K. Zhang;Jinge Liu;C. Tan;G. Wang;Xiaoguo Song;Bo Chen-;Liqun Li;Jicai Feng
中科院分区：
文献类型：
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作者：
K. Zhang;Jinge Liu;C. Tan;G. Wang;Xiaoguo Song;Bo Chen-;Liqun Li;Jicai Feng
为了改善不混溶且非反应性的Mg/Ti体系的冶金结合，在激光热传导焊接过程中，采用电镀镍作为中间元素，与Mg和Ti同时发生反应。研究了激光功率对焊接质量的影响，并分析了Ni涂层参与的界面反应。借助数值模拟阐明了元素扩散机制。采用1200W～1800W合适的激光功率，获得了可靠的接头，界面处形成了Ti2Ni和Ti固溶体的连续反应层。反应层厚度并非随激光功率的增加而单调增加。 Mg侧熔合区弥散分布着Mg-Al-Ni三元相。电镀Ni的扩散受到Mg侧和Ti侧双向机制的影响，导致反应层厚度的变化。激光功率为1500W时，最大拉剪载荷可达144N/mm（约为母材AZ31B镁合金接头效率的53.3%），接头强度和断裂模式与界面反应和镁侧焊缝形貌两个方面有关。结果，基于适当的界面冶金结合和镁侧无焊接缺陷，实现了可靠的连接。
To improve the metallurgical bonding of immiscible and nonreactive Mg/Ti system, Ni electro-coating was employed acting as an intermediate element by reacting with both Mg and Ti in laser heat-conduction welding process. Influence of laser power on welding quality was investigated and interfacial reaction with participation of Ni coating was analyzed. The elemental diffusion mechanism was clarified with the assistance of numerical simulation. Reliable joints were obtained with suitable laser powers ranging from 1200 W to 1800 W. Continuous reaction layer of Ti2Ni and Ti solid solution formed at the interface. The reaction layer thickness was not monotone increasing with increase of laser power. Mg-Al-Ni ternary phase dispersed in fusion zone at Mg side. Diffusion of electroplated Ni was influenced by a bidirectional mechanism to Mg side and Ti side, which resulted in the variation of reaction layer thickness. The maximum tensile-shear load could reach 144 N/mm (about 53.3% of joint efficiency of base metal AZ31B Mg alloy) when laser power was 1500 W. Joint strength and fracture mode were associated with two aspects: interfacial reaction and weld appearance of Mg side. As a result, reliable joining was realized based on appropriate interfacial metallurgical bonding and no weld defects at Mg side.