Multi-field coupling fatigue behavior of laser additively manufactured metallic materials: a review

Abstract

Laser additive manufacturing (AM) is an advanced green shaping technology that enables fast and flexible fabrication or repair of high-performance metallic materials. Since the component with the complex structure can be directly shaped by AM technologies, and then it can not only achieve the increase of the production efficiency of the AM component, but also the reduction of the component weight. Therefore, AM technologies are extensively used in the aerospace and automotive industries. Moreover, since AM components are usually in service under the conditions of static or complex dynamic cyclic loading, the fatigue performance of AM components is a key consideration during the service process. However, during the additive manufacturing process, the intrinsic AM defects such as lack of fusion (LOF) and unmelted particles will inevitably be formed, causing the stress concentration in the local area of the AM component, thus deteriorating the fatigue performance of the AM component. At the same time, since the defects in AM component can be reduced by the post-treatments or heat treatments but may not be fully eliminated, and therefore, the presence of the intrinsic AM defects tends to lead to unstable fatigue properties of the AM components compared with the components prepared by conventional manufacturing technologies. This work mainly reviews the latest research progress in improving the fatigue properties of superalloys manufactured by laser directed energy deposition (L-DED) and laser powder bed fusion (L-PBF) techniques. The research results of AM titanium alloys, nickel-based alloys and iron-based alloys in this field are highlighted, and the low-cycle fatigue, high-cycle fatigue behaviors and fatigue crack propagation processes of these alloys under multi-field coupling and general testing conditions are compared and reviewed. In addition, this review also analyzes the effects of defects, microstructures, and printing processes, post-treatments, and heat treatments on the fatigue properties of the AM superalloys, and also introduces the relevant fatigue mechanical models, and provides an outlook for important future development directions in this research field.