The reduction of agglomeration of particulate reinforcement in friction stir processing and elimination of joint line remnant in friction stir welding depends on stirring ability of friction stir tool. The magnitude of stirring is indicated by the intensity of material inter-mixing in tool interacted region. Present investigations analyse the influence of geometrical aspects of classical friction stir tool on the intensity of material intermixing, location of high stir regions and void formation during the steady-state phase of friction stir welding. The classical tool was chosen as its geometrical features undergo minimal wear in the harsher processing environment. Investigating material mixing using metallic inserts have their shortcomings due to different flow properties of insert/marker and parent material. Therefore, bi-colour plasticine configuration possessing primary colours was adopted to understand the level of intermixing. The hue attribute of the generated secondary colour was utilised to identify and quantify material mixing. Experimental results revealed that the pin diameter positively influenced mixing and negatively affected void formation. Shoulder size and pin taper angle aided in the closure of void with inferior mixing. The intensity of mixing enhances on selection of tools possessing a shoulder to pin diameter ratio of 2.5. Finite element simulation studies were conducted to understand the reasons for mixing under certain tooling conditions. Since material subjected to stirring is concentrated primarily on a portion of advancing side, components of shear strain, shear strain rates, shear stress and velocity were tracked for this portion of processed material during its interaction with tool pin for one complete rotation.

减少摩擦搅拌过程中颗粒增强物的团聚和消除摩擦搅拌焊接中的接缝残留物取决于摩擦搅拌工具的搅拌能力。搅拌的幅度由工具相互作用区域中材料相互混合的强度指示。目前的研究分析了经典的搅拌摩擦工具的几何形状对搅拌摩擦焊接稳态阶段材料混合强度，高搅拌区域的位置和空洞形成的影响。选择经典工具是因为它的几何特征在恶劣的加工环境中受到的磨损最小。由于插入物/标记物和母体材料的流动特性不同，使用金属插入物进行材料混合的研究存在其缺点。因此，采用具有原色的双色橡皮泥构型来理解混合水平。生成的辅助颜色的色相属性用于识别和量化材料混合。实验结果表明，销钉直径对混合有积极影响，而对空洞形成有不利影响。肩部尺寸和销钉锥角有助于在混合不良的情况下封闭空隙。选择肩径比为2.5的工具会增强混合强度。进行了有限元模拟研究，以了解在某些加工条件下混合的原因。由于受到搅拌的材料主要集中在前进侧的一部分，因此剪切应变，剪切应变率，