5th International High Manganese Steel Conference - HMNS 2022

Recently, the new designing concepts for medium-Mn steel have been promoted such as micro-alloyed steels to improve mechanical properties. Several authors reported that micro-alloying was effective to enhance the strength and toughness of medium-Mn steels. In this study, we elucidated the unknown role of micro-alloying element addition to a medium-Mn steel and explored why a micro-alloyed...

With an increasing demand for high-strength steel with lean-alloyed composition, the medium-Mn steels containing ~3-12 wt.% Mn and ~0.05-0.4 wt.% C have garnered significant attention as next-generation advanced high-strength steels. The α′ martensite microstructure could be observed after hot and cold rolling of the corresponding steel, and it turns to the two-phase microstructure of α...

The strength of ausformed martensite is higher than that of as-quenched martensite. This is believed to be because the dislocation introduced by ausforming is inherited after quenching, and the dislocation density of ausformed martensite is higher than that of as-quenched martensite. However, there is little studies about the detailed relationship between the mechanical properties and...

The strength-ductility balance of steels is strongly dependent on their microstructure characteristic which dominates strain distribution, such as texture, grain morphology, and dispersed hard- and/or soft-phases. It is generally known that addition of Mn above 10% decreases stacking fault energy, which results in the occurrence of γ→ε→α’ martensitic transformation. The microstructure formed...

9%Ni steels, which have excellent strength and toughness in the low temperature range, are used as the cryogenic steel mainly used for LNG storage tanks, Mn is similar to Ni as an alloying element in steels, such as improvement of hardenability and stabilization of γ, so that Mn is expected as an alternative element to Ni. However, because the addition of Mn to steel causes remarkable...

Medium manganese sheet steels show an excellent combination of strength and ductility. Typically, they have a duplex type microstructure consisting of ferrite and austenite layers after cold rolling and subsequent intercritical annealing. The thermomechanical rolling produces a mixture of bainite, martensite and retained austenite instead of typical duplex microstructures. Their forming...

The intercritical annealing approach is widely used as a heat treatment for the formation of a dual-phase structure, composed of ferrite and austenite in medium-Mn alloys. By controlling the temperature, it is possible to control a fraction of both phases. Then, during deformation, the austenite undergoes martensite transformation, enhancing the plasticity of the steel. Depending on the...

Medium-Mn steels (MMnS) with very low (≤ 0.05 wt.%) carbon content exhibit improved cold-formability but limited strength due to the deficient strain hardening. A combination of nano-precipitation and enhanced transformation-induced plasticity (TRIP) effect is a promising approach to improve the strength and ductility of such MMnS. In this study, a low-carbon (0.05 wt.%) medium-Mn steel (MMnS)...