Fatigue fracture is the main failure mode of metal components in long-term service under cyclic or alternating load. Welding is an important metal connection method. The weld joint is the site of the same metal or different metal connected with each other, and the chemical composition, microstructure, and mechanical properties in the weld joint change gradually. As the service environment of metal components becomes more and more severe, the fatigue of welded joints becomes more and more prominent when they are in long-term service under cyclic or alternating load. Therefore, how to improve the fatigue life of metal components with welded joints has become an important scientific issue. Due to the complexity of metal welding process, the fatigue lives of metal components with welded joints are affected by many factors. Firstly, the key factors affecting the fatigue life of weld joint are summarized, including the microstructure evolution, welding defects, stress concentration, residual stress and so on. Attributed to microstructure evolution, geometric structure changes, and the introduction of welding defects, the fatigue properties of welded joints are usually decreased markedly as compared with that of the matrix. Subsequently, a variety of weld fatigue life extension technologies are summed up, such as weld grinding technology, hammering technology, TIG dressing technology, high frequency mechanical impact technology, low transformation temperature filler materials technology, and so on. According to the characteristics of the weld fatigue life extension technology, it can be roughly divided into three categories: weld shape modification method, weld residual stress method, and low phase change temperature material method. © 2021, Materials Review Magazine. All right reserved.
