搅拌摩擦固相修复技术研究现状及发展方向

金属结构件在生产和使用过程中易出现裂纹、孔洞和沟槽等缺陷，搅拌摩擦焊具有热输入量小、焊接变形小和焊接效率高等优点，在金属材料修复领域具有巨大的发展潜力。首先总结了搅拌摩擦焊修复的修复性能和特点。由于搅拌摩擦焊修复仅能修复裂纹及体积较小的沟槽等缺陷，对于其他类型缺陷难以有效修复。针对搅拌摩擦焊修复的局限性，介绍了基于搅拌摩擦焊原理的搅拌摩擦点焊修复和搅拌摩擦增材修复。搅拌摩擦点焊修复分为回填式搅拌摩擦点焊修复、填充搅拌摩擦焊修复和摩擦塞焊修复，主要用于匙孔等孔洞类缺陷的修复。阐述了各类搅拌摩擦点焊修复的工作原理、修复接头性能和强化方式，并对比分析了各类工艺的不足之处。搅拌摩擦增材修复分为复合增材修复和增材搅拌摩擦沉积修复，主要用于大面积、大体积类表面缺陷的修复，论述了各类搅拌摩擦增材修复的作用机制、沉积层性能和工艺特点。最后对搅拌摩擦点焊修复和搅拌摩擦增材修复存在的问题及未来发展方向进行了展望。

Research Status and Development Direction of Friction Stir Solid Phase Repair Technology

For a large number of metal structural parts used in the manufacturing industry today, cracks, holes and grooves and other defects are inevitable in the production and use process, affecting the use of metal structural parts, and in serious cases even lead to structural scrap. Therefore, in order to ensure the reliability of the use of metal structural parts, the welding repair technology for defects in metal structural parts has practical engineering significance. Compared with traditional fusion welding, friction stir welding has the advantages of low heat input, small welding deformation, high welding efficiency, low welding temperature, small grain size and no obvious defects. In addition, its weld has excellent morphology and performance, so it has great potential for development in the field of metal material repair. However, friction stir welding can only be used to repair cracks, small grooves, so other defects and other types of defects are difficult to be repaired effectively. In view of the limitations of friction stir welding repair, friction stir spot welding repair and friction stir additive repair based on the principle of friction stir welding are introduced. Friction stir spot welding repair was mainly divided into refilled friction stir spot welding repair, filling friction stir welding repair and friction plug welding repair, mainly used for keyhole and other hole type defect repair. By controlling the process parameters such as tool speed, welding time and welding force, the grain size can be refined and the repaired joints with excellent mechanical properties can be obtained. However, it is also found that the refilled friction stir spot welding repair process is complex and the repair area is limited by the size of the welding tool. For filling friction stir welding repair and friction plug welding repair, suitable consumable welding tool materials need to be selected. The working principle, joint performance and strengthening methods of various kinds of friction stir spot welding repair are expounded, and the shortcomings of various processes are compared and analyzed. Friction stir additive repair is mainly divided into composite additive repair and additive friction stir deposition repair, mainly used for large area and large volume surface defect repair. Composite additive repair is a repair technology that combines cold spraying and friction stir processing, and has great potential for development in the field of repairing large defects on the surface of parts. Additive friction stir deposition repair is a combination of friction stir welding and raw material addition, using the heat generated by the friction of a high-speed rotating non-self-consuming deposition tool to deposit solid or metal powder raw materials, layer by layer, at a high deposition rate, so as to complete the repair. However, due to the poor bonding strength of the deposited material to the substrate for composite additive repair and additive friction stir deposition repair, the performance of the repaired area does not meet the requirements for industrial use, and further exploration and research is needed. The current research status of three stir friction solid phase repair technologies are summarized:friction stir welding repair, friction stir spot welding repair and friction stir additive repair, and the mechanism, properties and technological characteristics of various kinds of friction stir additive repair are discussed in detail, pointing out the repair area performance, current problems and development trends of the three technologies.