异种搅拌摩擦焊接AA2024-7075接头沿厚度方向上的电子背散射衍射分析

EBSD analysis of the nugget zone in the dissimilar friction stir welded AA2024-AA7075 joint along weld thickness

摘要:

本研究以5mm厚的AA2024-T351和AA7075-T651铝合金板材进行搅拌摩擦对接焊，研究了异种铝合金搅拌摩擦焊AA2024-7075接头焊核区沿厚度方向的微观组织演化。研究结果表明：焊核区的晶粒尺寸从焊缝顶部到底部依次降低。轴肩区和焊缝底部区域的再结晶组分低于焊缝中心区。焊核区形成了简单的剪切织构且织构分布并不均匀。轴肩区主要是B 和?B织构组分，而底部区域主要是A 和?A织构组分，C织构组分则出现在中心区域。中心区域的织构强度低于焊核顶部和底部区域，这主要是由于该区域出现了洋葱环，是材料混合区域，使得晶粒取向更为随机。

Abstract:

In this investigation, the plates of AA2024-T351 and AA7075-T651 with 5 mm thickness were butt joined by friction stir welding. The microstructural evolution in the nugget zone (NZ) of the dissimilar AA2024-7075 joints along the weld thickness direction was studied. The results indicated that the grain size of the NZ decreases from the top to the root of the joint. The fraction of dynamic recrystallization in the shoulder affected zone (SAZ) and the weld bottom is lower than that in the center of the NZ. Simple shear texture can be developed in the NZ and the texture distributions are heterogeneous. The SAZ consists of B and?B components, while A or?A components are the major textures at the bottom position. C component is found in the middle of the NZ. The texture intensity in the middle of the NZ is lower than that of at the top and bottom. This is mainly due to the presence of the onion ring, in which materials mixing occurs, resulting in a more random grain orientation.