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为研究NZ30K稀土镁合金和AZ31镁合金的异种材料激光焊接,对采用CO2激光焊成的AZ31与NZ30K异种对接焊接头组织和性能进行了分析。在激光功率为4～5kW,焊接速度为4m/min时获得了成形良好的异种镁合金焊接接头。对获得的焊接接头进行了接头组织分析、焊缝区合金元素分布及析出相的分析及接头硬度和拉伸性能的测量。金相观察发现,异种镁合金激光焊缝是两种母材的熔合,在宏观上两种母材成分未完全混合在一起,且相应成分的组织区域呈波浪状夹杂态。X射线衍射(XRD)检测显示焊缝中存在α-Mg、Mg17Al12及Mg12Nd等相组织。扫描电镜(SEM)观察进一步显示了焊缝区存在着不同化学成分区域,焊缝晶粒显著细化。接头元素分布情况表明焊缝合金元素的分布由一侧熔合线至另一侧熔合线存在明显的浓度梯度。焊缝硬度不低于母材硬度;接头抗拉强度为169MPa,低于两种母材的抗拉强度。
In order to study the laser welding of dissimilar materials of NZ30K magnesium alloy and AZ31 magnesium alloy, the microstructures and properties of dissimilar butt welded joints of AZ31 and NZ30K using CO2 laser welding were analyzed. When the laser power is 4 ~ 5kW and the welding speed is 4m / min, a well-formed dissimilar magnesium alloy welded joint is obtained. The obtained welded joints were analyzed by joint organization, the distribution of alloying elements in the weld zone and the analysis of precipitated phases and the measurement of joint hardness and tensile properties. Metallographic observation found that the heterogeneous magnesium alloy laser welding is the base metal of the two fusions, macroscopically the two base metal components are not completely mixed together, and the corresponding composition of the organizational area wavy inclusions. X-ray diffraction (XRD) examination revealed the presence of α-Mg, Mg17Al12 and Mg12Nd phase in the weld. Scanning electron microscopy (SEM) observation further showed that there are different chemical composition of weld zone area, weld grain refinement significantly. The joint element distribution shows that the distribution of alloying elements in the weld has a significant concentration gradient from the fusion line on one side to the fusion line on the other side. Weld hardness of not less than the hardness of the base metal; joint tensile strength of 169MPa, lower than the tensile strength of the two base metals.