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采用熔化极惰性气体保护电弧焊方法(MIG)实现镁合金和低碳钢的连接,并研究焊接热循环特点和镁-钢对接接头的显微组织及力学性能。研究结果表明,在焊接过程中,接头的温度场分布是不均匀的。镁合金焊缝金属为细小的等轴晶结构。在镁/钢界面存在主要由AlFe、AlF_3和Mg(Fe,Al)_2O_4相组成的过渡层,这一过渡层是镁-钢接头的最薄弱环节。焊接线能量和焊缝Al含量对镁-钢接头的抗拉强度具有明显的影响。焊接线能量由1680J/cm增至2093J/cm,接头强度明显增加,这主要归因于镁/钢界面反应。增加焊缝Al含量至6.20%,镁-钢接头强度可达192 MPa,为AZ31镁合金母材强度的80%。因此,选择合适的焊接线能量和焊缝Al含量有利于改善镁-钢接头的抗拉强度。
The connection between magnesium alloy and mild steel was achieved by means of MIG welding. The microstructure and mechanical properties of the welding thermal cycle and the magnesium-steel butt joint were studied. The results show that in the welding process, the joint temperature distribution is not uniform. Magnesium alloy weld metal is a fine equiaxed crystal structure. At the magnesium / steel interface there is a transitional layer composed mainly of AlFe, AlF_3 and Mg (Fe, Al) _2O_4 phases, which is the weakest link for magnesium-steel joints. The welding line energy and weld Al content have a significant effect on the tensile strength of magnesium-steel joints. The energy of the welding wire increased from 1680J / cm to 2093J / cm, and the joint strength increased obviously, mainly due to the magnesium / steel interfacial reaction. Increasing the weld Al content to 6.20%, magnesium-steel joint strength up to 192 MPa, the strength of the AZ31 magnesium alloy base metal 80%. Therefore, the choice of appropriate welding line energy and weld Al content is conducive to improving the tensile strength of magnesium-steel joints.