5083-H321铝合金板材搅拌摩擦焊缝组织演变

The Microstructural Evolution of Friction Stir Welded 5083-H321 Aluminum Alloy Plates

采用搅拌摩擦焊接法焊接了5083-H321铝合金板材,借助光学显微镜、扫描电镜、背散射电子衍射分析仪及取向显微成像分析技术对焊缝与母材的组织进行了对比性研究.结果表明,该合金板材的焊缝无宏观缺陷,焊缝成形区呈现出与母材明显不同的组织特征;搅拌摩擦焊使该合金板材中大量的小角度晶界转化为大角度晶界,母材和焊核区的晶粒尺寸分布范围分别为6～55μm及15～30μm,晶粒纵横比分布范围分别为2～8和1.5～3,焊核区呈现均匀化与等轴化的动态再结晶特征.

The 5083H321 aluminum alloy plate was jointed by friction stir welding. The comparative studies of the organization of weld and base metal were conducted with optical microscopy, scanning electron microscopy, electron back scattered diffraction and orientation imaging microscopy. The results show that there are no macroscopic defects in the weld. The organizational characteristics are obviously different between the welding seam and the base metal. Friction stir welding makes a large number of lowangle grain boundaries transform into highangle grain boundaries in the nugget zone. The grain size distribution of the base metal and the nugget zone is 6~55 μm and 15~30 μm respectively while the shape aspect ratio is 2~8 and 15~3 respectively. The grains of the nugget zone show homogeneous and equiaxed morphology characteristics of dynamic recrystallization.