旋转速度对铝/钢填丝搅拌摩擦焊接头性能的影响

Effect of Rotational Speed on Properties of Aluminum/Steel Wire-filler Friction Stir Welding Joints

铝与钢复合结构是实现载具轻量化的有效途径之一,为了指导铝与钢搅拌摩擦焊接技术的工业应用,必须开展铝与钢异种材料的搅拌摩擦焊接工艺试验。采用填丝搅拌摩擦焊对2.8 mm厚的Q235冷轧钢和2.9 mm厚的5A06铝合金异种金属进行对接焊,分析接头的宏观形貌、微观结构、组织成分、微观硬度和断口形貌。结果表明:C形界面的内凹深度、界面IMC层厚度随旋转速度的增加而增加;大量Al3Ni颗粒呈弥散分布于焊缝中;在旋转速度为420 r/min时,界面IMC层为厚度1.3μm的FeAl相,接头主要断裂于焊核区,断裂模式为韧性断裂,平均抗拉强度为240.3 MPa,正弯角度为19.3°、背弯角度为13.4°;接头显微硬度呈不对称分布,表现出阶跃特征。

Aluminum and steel composite structure is one of the effective ways to achieve lightweight carriers,in order to guide the industrial application of aluminum and steel friction stir welding technology,aluminum and steel dissimilar materi‐als must be carried out friction stir welding process tests.The friction stir welding technology is used for the butt welding of 2.8 mm thick Q235 cold-rolled steel and 2.9 mm thick 5A06 aluminum alloy dissimilar metals,the study of the macroscopic morphology,microstructure,composition,microhardness and fracture appearance of the joint.The results show that the C shape interface concave depth and interface IMC layer thickness increase with the increase of rotational speed;a large num‐ber of Al3Ni particles diffusely distribute in the weld;at a rotational speed of 420 r/min,the interface IMC layer is 1.3μm thick FeAl phase,the joint is mainly fractured in the weld core zone and the fracture mode is ductile fracture,the average tensile strength of the joint is 240.3 MPa,the forward bending angle is 19.3°and back bending angle is 13.4°;the microhard‐ness of the joint asymmetrically distributes and shows step characteristics.