Effect of different beam offset on microstructure configuration,thickness of intermetallic compound layers,crack defects and mechanical properties of aluminum alloy/steel electron beam welded joints was analyzed.The results showed that with the increment of beam offset,the Fe-Al intermetallic compound grains in the weld vanished,gradually the eutectic substance on the crystal border decreased,and the configuration of the intermetallic compound layer became less complicated and the thickness of it became smaller.When the beam offset was relatively small,cracks existed in the compound layer;when the beam offset was relatively large,cracks existed in the weld near the compound layer.The optimal tensile strength of the joints was 125 MPa as beam offset 0.5mm.The morphology of the fracture changed with different beam offsets.The optimal thickness range of the compound layer was about 0.9~1.55 μm,which was determined by the characteristic of the electron beam.%分析了不同偏束距离对铝合金/钢异种金属EBW接头的组织形态、化合物层厚度、裂纹缺陷以及接头性能的影响.结果表明,随着偏束距离的增加,焊缝中的Fe-A l化合物颗粒逐渐消失,晶界上的共晶体减少,化合物层形态由复杂变简单,厚度减小.偏束距离较小时,在化合物层附近的焊缝中存在裂纹缺陷;偏束距离较大时,在化合物层上存在裂纹.偏束距离为0.5 mm时,接头最高抗拉强度为125 MPa,不同偏束距离下的断口宏观形貌有显著不同.化合物层厚度最佳范围为0.9~1.55μm,这个范围是由电子束热源特性决定的.
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