Abstract Nirosta H400 is an ultrahigh-strength stainless steel that has an unstable austenitic microstructure which work hardens to martensite. The alloy was developed for volume production in the automobile industry primarily for weight reduction. This datasheet provides information on composition, physical properties, elasticity, and tensile properties. It also includes information on high temperature performance and corrosion resistance as well as forming, heat treating, and joining. Filing Code: SS-959. Producer or source: ThyssenKrupp Nirosta GmbH.