A low density, high strength medium-Mn steel was processed to produce a bimodal duplex microstructure consisting of coarse grained γ-austenite with fine δ-ferrite grains decorating the γ-austenite boundaries. Using a combination of ex situ analysis and in situ neutron diffraction, the deformation mechanisms and lattice strains within each phase were identified for specimens undergoing uniaxial tension during room and elevated temperature loading up to 473 K. The coarse-grained high stacking fault energy γ-austenite deformed by dislocation glide, providing work hardening and ductility. Simultaneously, the fine grained δ-ferrite produced an elevated yield strength by strengthening the steel via a composite reinforcing mechanism. Neutron diffraction reveals that the yield strength reduction at elevated temperatures is due to a reduction in the δ-ferrite strength. The resulting combination 1200 MPa ultimate strength and 0.3 ductility achieved in this microstructurally engineered bimodal duplex steel exceeds that of typical hot worked medium-Mn steels.

对低密度，高强度的中锰钢进行加工，以产生双峰双相组织，该组织由粗晶粒的γ-奥氏体组成，而细的δ-铁素体晶粒装饰了γ-奥氏体的边界。使用的组合易地分析和原位鉴定了在室温和高达473 K的高温载荷下经受单轴拉伸的试样在每个相中的中子衍射，形变机理和晶格应变。粗粒高堆垛层错能γ-奥氏体由于位错滑移而变形，提供了工作硬化和延展性。同时，通过复合增强机制对钢进行强化，细晶粒的δ铁氧体产生了较高的屈服强度。中子衍射表明，高温下屈服强度的降低是由于δ-铁素体强度的降低。在这种微结构设计的双峰双相钢中获得的1200 MPa极限强度和0.3延展性的组合超过了典型的热加工中锰钢。