Research progress on mechanical properties of additive manufacturing Ti-6Al-4V alloy under static and dynamic loading

Additive manufacturing (AM) possesses significant advantages in processing critical components in aerospace and defense fields that feature intricate and geometrically complex designs, thanks to its high design freedom and rapid prototyping capabilities. Ti-6Al-4V titanium alloy, renowned for its low density, high specific strength, and creep resistance, is widely utilized in crucial parts of spacecraft and weaponry that frequently endure impact loads. A thorough understanding of the mechanical properties and underlying mechanisms of AM Ti-6Al-4V alloy under static and dynamic loads is crucial for enhancing the service performance of these components. This paper systematically reviews and summarizes the latest advancements in the mechanical response of AM Ti-6Al-4V titanium alloy, aiming at offering a scientific foundation and technical approach to promote the application of key load-bearing components fabricated by additive manufacturing process under extreme conditions. It begins with a brief overview of the classification and working principles of typical metal additive manufacturing technologies including laser direct energy deposition (LDED), laser powder bed fusion (LPBF) and electron beam melting (EBM). Typical microstructure of different metal additive manufacturing technologies is compared according to their thermal history characteristics, such as preheating treatment and cooling rate. Subsequently, it outlines the research efforts on the quasi-static tensile and dynamic compressive properties of AM Ti-6Al-4V alloy, comparing them with the mechanical properties of cast and forged Ti-6Al-4V components. Both quasi-static tensile and dynamic compressive properties of AM Ti-6Al-4V alloy are dependent on deposition direction, and its fundamental physical mechanisms are only partially understood. Furthermore, the paper delves into the correlation mechanisms between the microstructure and mechanical behavior of typical metal additive manufacturing titanium alloys. Additionally, it summarizes commonly used post-processing techniques, to mitigate the anisotropic mechanical response of AM Ti-6Al-4V alloy under static loads. The prospects are provided for AM titanium alloy research directions including mechanical response of at extreme environmental load, relationship between deposition direction and dynamic mechanical properties, correlation mechanisms between the microstructure and dynamic mechanical behavior, and dynamic constitutive model.