镁和钢异种金属熔焊接头微观组织分析
Microstructure of dissimilar metal joint with magnesium alloy AZ31B and steel 304 for laser-tungsten inert gas lap welding
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摘要: 采用激光-氩弧复合热源焊接工艺对AZ31B变形镁合金和304钢进行搭接焊研究。通过调整焊接参数获得最佳焊接成形,并采用扫描电镜、电子探针等先进测试手段观察焊接接头的微观组织。结果表明,复合热源焊接是一种适用于Mg和Fe异种金属材料连接的有效方法,通过在过渡区域形成新相可以实现Mg和Fe的有效连接。试验还发现,由于氧化程度存在差异,镁铁焊接接头过渡区域会产生不同新相,一种是"竹节状"的MgO相,一种是连续的(Mg)x(Fe)y(O)z复合相,而两种新相的存在获得了两种不同的镁钢连接方式。在后者形成过程中,发现镁扩散现象。Abstract: The lap welding of magnesium alloy AZ31B and steel 304 dissimilar joint by laser-tungsten inert gas(TIG)welding was investigated, and the microstructure was analyzed by SEM, EPMA etc.The resultsshowed thatMg andFe can be joined effectively due to the new phase forming in transition zone of the joint.It also found the new phases were different because the extent to oxidation was different.One was "bamboo" MgO phase, another was consecutive MgxFeyOz phase.During the latter phase forming, the phenomenon of Mg diffusion can be found.
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