铝合金T形接头静止轴肩搅拌摩擦焊接及组织性能分析

Analysis of microstructure and mechanical properties of the aluminum alloy T-joint welded by stationary shoulder friction stir welding

关键词:  T形接头  静止轴肩搅拌摩擦焊接  显微硬度  拉伸性能  断裂位置

Key words:  T joint  stationary shoulder friction stir welding  microhardness  tensile property  fracture location

摘要:

成功实现了2219C10S铝合金T形接头的静止轴肩搅拌摩擦焊接，焊缝表面光滑平整，无明显减薄.从基板背部进行的超声相控阵检测结果表明，基板与肋板对合面全部焊透，接头内部无超标缺陷.接头横截面宏观金相可以观察到2个以肋板中心线对称分布的焊缝轮廓，单侧焊缝轮廓均超过了肋板中心线.接头横截面显微硬度分布趋势呈独特的“U”形，焊核区显微硬度最低.T形接头两个方向的拉伸试样起裂点位于“拉伸方向板材与接头R₁圆角的相切处”，但拉断试样断裂面的横穿区域存在较大差异，这也是沿肋板方向的抗拉强度比沿基板方向低20 MPa的主要原因.

Abstract:

2219C10S aluminum alloy T-joint was successfully performed by stationary shoulder friction stir welding. The weld surface is smooth and has no obvious thickness-reduction. The PAUT testing on the back of the substrate plate shows that all the surfaces between the substrate and rib plates were welded thoroughly. The macro-structure revealed two weld contours symmetrically distributed in the center of the rib plate. The unilateral weld contours also exceeded the center line of the rib plate. The microhardness distribution of the joints shows a unique U-shaped distribution, and the microhardness of the weld nugget zone was the lowest. The crack of tensile specimens with the two directions of T-joint initiated at the tangent of the tension plate and the corner of the joint R1. However, the transverse areas of the fracture surface for the two types of tensile specimens are quite different. This is the main reason why the tensile strength along the direction of rib plate was 20 MPa lower than that along the direction of the substrate plate.