主催: The Iron and Steel Institute of Japan
p. 241-243
Low-density ultrahigh-strength steels (LD-UHSS) have garnered significant interest for lightweight design of automotive and aerospace components. However, their application has been limited by poor formability and weldability resulting from the inclusion of aluminum (Al). In this study, we present a successful approach for designing and fabricating a series of LD-UHSS using laser powder bed fusion with in-situ alloying. The addition of Al not only reduces the density of the newly designed LD-UHSS but also significantly strengthens the steels through the precipitation of the B2 phase. Compared to conventional low-density steels, the strength of the δ-ferrite phase in LD-UHSS is notably higher due to the smaller grain size and the presence of massive precipitates, enhancing the work hardening capacity. Additionally, the B2 phase in the developed LD-UHSS exhibits a finer structure, further reinforcing the matrix. However, it should be noted that excessive Al addition can result in steel brittleness due to the extensive precipitation of the B2 phase and increased fraction of δ-ferrite. Additive manufacturing offers a viable pathway for producing LD-UHSS, and the mechanical performance can be effectively optimized by tailoring key phases such as the B2 phase, metastable austenite, and δ-ferrite. This research opens new avenues for the development of lightweight, high-strength steels for various industrial applications.
