Friction stir welding is commonly used to join metals because it is environmentally friendly and provides higher fatigue strength than electric resistance spot welding, riveted connections, and screw connections. Alternative methods that do not reduce the fatigue strength, such as friction stir spot welding (FSSW), are being investigated. However, several studies have proven that FSSW joints are not sufficiently qualified for industrial usage. Defects such as keyholes, cavities, and cracks that form during classic FSSW with a screw stirring tool have not yet been eliminated. Some studies have demonstrated that the geometry of the stirring tool and the shoulder profile affect the quality of the joint. In this study, five pinless stirring tools with different shoulder profiles were designed to avoid the formation of cavities and cracks. The effect of the stirring tool on the mechanical properties and macro- and microstructural material properties during the joining process were examined.

搅拌摩擦焊通常用于连接金属，因为它对环境友好，并且比电阻点焊，铆接和螺纹连接具有更高的疲劳强度。正在研究不降低疲劳强度的替代方法，例如搅拌摩擦点焊（FSSW）。但是，一些研究证明，FSSW接头不足以用于工业用途。尚未消除使用螺丝搅拌工具在经典FSSW期间形成的诸如锁孔，孔洞和裂纹之类的缺陷。一些研究表明，搅拌工具的几何形状和肩部轮廓会影响关节的质量。在这项研究中，设计了五种不同肩部轮廓的无销搅拌工具，以避免形成空腔和裂纹。