Development of hot rolled ultra-high strength steel with enhanced mechanical properties

Hot rolled ultra-high strength steel with a gauge range of 3-10mm (0.118¨ - 0.395¨) was processed using conventional slab caster and hot strip mill technology at Stelco Inc. (Stelco) to meet standard industry specifications along with additional unique customer requirements. The effects of chemical composition, steelmaking and hot rolling process parameters on microstructure, precipitation behavior, and mechanical properties were studied. Both Grade 90 (620Mpa, Stelco trademarked STELMAX ^TM 90) and Grade 100 (690MPa, STELMAX ^TM 100) products met strength requirements in longitudinal and transverse directions. Furthermore, these ultra-high strength steels exhibited excellent ductility, impact toughness, edge stretchability and bendability. These newly developed steels have extensive applications in automobile safety components, light-weight construction, piping/tubing and off shore structures. These steels also have the potential to replace heat treated material currently being used without compromising component performance.