【作者】 石常亮；

【导师】 冯吉才； 何鹏；

【作者基本信息】 哈尔滨工业大学 ， Materials Processing Engineering， 2006， 硕士

【摘要】 本文针对汽车工业中铝合金和镀锌钢板的轻量化结构制造,对铝合金与镀锌钢薄板搭接件进行了异种材料冷金属过渡（CMT）钎焊,研究了工艺参数对焊缝表面成形、接头组织结构及力学性能的影响。1mm厚锻铝6061和镀锌钢板异种材料的CMT焊接性试验结果表明,接头为典型的搭接接头形貌,焊接接头被分成熔化区、中间界面区、过渡界面区和富锌区。熔化区是由α-Al和Al-Si共晶相组成;中心界面区化合物层的厚度大约为7⁸μm,反应层为致密的FeAl₃金属间化合物;过渡界面区反应层的厚度为4⁵μm,在靠近熔化区的一侧有少量的白亮相,其成分为铝锌α固溶体,在靠近钢一侧致密的灰色相为FeAl₃金属间化合物;富锌区是由铝锌α相固溶体和铝锌共析相及铝锌共晶体组成。分析了各种焊接规范参数对1mm厚纯铝1060和镀锌钢的CMT焊接接头外观和微观组织的影响,进行了相应试件的力学性能测试。试验结果表明:焊接热输入量越大,反应层厚度越大;随着焊接热输入量的增加,中间反应层的组织成分也由Fe2Al5变为FeAl2和FeAl3金属间化合物。结果表明,本实验得到的最佳焊接规范为焊枪对中、送丝速度3.9m/min、焊接速度13.9mm/s、焊接电流66A、焊接电压11.8V,此时可以得到焊缝外观均匀、成形好的搭接接头,其拉剪强度为82.6 MPa。通过研究钢板上不同锌层厚度对焊接接头的影响发现,在整个焊接过程中,锌很好的起到了促进熔化的铝在钢板表面润湿铺展的作用,在一定范围内锌层越厚对铝和钢的焊接越有利。当镀锌层较薄时,需要增大焊接热输入量,以提高液态铝在钢板表面的润湿。更多还原

【Abstract】 Aim to application of aluminium alloy and galvanized steel for automobile industry, the dissimilar joint between aluminium alloy and galvanized steel sheet during cold metal transfer brazing was analyzed. The features of the dissimilar joint and the effect of the weld parameters on mechanical properties were discussed.The results of dissimilar joints welding between 1mm thick aluminium alloy 6061 and galvanized steel show that a good lap joint was formed, which was divided into welded metal, middle interface, transitional interface and zinc-rich zone. Welded metal is composed ofα-Al and Al-Si eutectic; The thickness of middle interface is 7 to 8μm, composed of FeAl₃ intermetallics; The thickness of transitional interface is 4 to 5μm, composed ofαsolid solution and FeAl₃ intermetallics; Zinc-rich zone is composed of Al-Znαsolid solution, Al-Zn eutectoid and Al-Zn eutectic.By means of microstructure and mechanical properties analysis of the joints between 1mm thick aluminium 1060 and galvanized steel, the parameters of CMT brazing process were optimized. When heat input is increased, the thickness of interface layer increases, the composition of the middle interface also changes from Fe2Al5 to FeAl2 and FeAl3 intermetallics. When the torch in middle, wire feed rate 3.9 m/min, welding speed 13.9 mm/s, welding current 66 A , welding voltage 11.8 V, continuous, uniform and best shape joint was formed, the shearing strength was up to 82.6 MPa.By the analysis of the effect of different zinc layer thickness on the joint, zinc element effectively promotes molten aluminium wetting the steel sheet, it is good to dissimilar joints between aluminium alloy and galvanized steel when the zinc layer is enough thick. More heat input is needed to promotes molten aluminium wetting the steel sheet when the zinc layer is thin.更多还原