Impact behaviors of additively manufactured metals and structures: A review

Additive manufacturing (AM) is a revolutionary, advanced, digital manufacturing and key strategic technology for the sustainable fabrication of novel materials and found its way into industry. This technology unlocks the constraints of traditional manufacturing technologies and meets the needs of the fabrication of high-performance parts with complex geometry. Since AM parts for use in i.a. aerospace and defense sector are usually subjected to high-speed impact loading conditions, their dynamic mechanical properties and failure characteristics become a major concern. This load condition also causes great challenges for the application of AM techniques to produce parts providing the required performance them and, thus, a periodic and critical assessment of new changes in the dynamic mechanical properties of metals and structures imparted by this novel AM technologies is justified. In this work, the principles, characteristics and development status of AM techniques and impact loading methods are firstly reviewed, then the macro-scale, meso-scale and micro-scale dynamic mechanical responses (dynamic yield and failure, strain rate sensitivity, adiabatic shearing, adiabatic temperature rise, thermal softening, grain refinement, texture evolution, phase transition, etc.) and dynamic deformation and failure mechanisms (dislocation slip, deformation twinning, dynamic recrystallization, etc.) of the AM-fabricated metals (titanium, aluminium, steel and nickel) and AM-fabricated lattice structures subjected to impact loading are evaluated and their influences are summarized. At last, prospects toward the development of AM and resulting products employed in the fields of aerospace and defense are outlined.