Grain boundary engineering tailoring the mechanical and corrosion properties of additively manufactured austenitic stainless steels: A review

Additive manufacturing (AM) technique has gained significant attention for its unique advantages in producing products with complex structures and customized designs. The complex grain boundaries (GBs) in AM metals and alloys, which differ from the straight ones in traditional manufacture counterparts, are mainly due to the layer-by-layer rapid melting and solidification process. Extensive research has detected similar complex GBs in various alloys, highlighting their universality in AM alloys. Using AM austenitic stainless steel (SS) as a case, this paper reviews recent studies on factors influencing grain boundary (GB) formation in AM austenitic SS, such as chemical composition, printing processes, and post-treatment. This review also describes the typical characteristics of these GBs, including elemental segregation, the coincidence with dislocation walls and boundary misorientation. Furthermore, the intrinsic relationship between the GB features and the mechanical and corrosion-resistance properties of the AM austenitic SS are explored. We hope this review can aid in regulating and custom-designing AM GBs, advancing the development of high-performance metal and alloys.