Elements Of X Ray Diffraction

Current state of Fe-Mn-Al-C low density steels

Thermomechanical processing of advanced high strength steels

Medium Mn transformation-induced plasticity steels: Recent progress and challenges

Recent progress in medium-Mn steels made with new designing strategies, a review

Coupled strengthening in a medium manganese lightweight steel with an inhomogeneously grained structure of austenite

Pitting corrosion behavior in advanced high strength steels

The size effect of α′ martensite constituents before annealing on the microstructure and tensile properties of intercritically annealed medium Mn steel was systematically investigated. The cold-rolled Fe–9Mn–0.05C (wt%) steel was austenized at three different temperatures, water-quenched to room temperature to vary the sizes of the martensite constituents, and then annealed at 640 °C for 10 min. When the austenizing temperature increased, the sizes of the prior austenite (γ) grains and of the packets and blocks of α′ martensite increased; however, the width of the laths changed only insignificantly. The annealed specimens had a dual-phase microstructure with lath-shaped ferrite (α) and retained γ (γR) phases. The volume fraction of γR decreased with increasing austenizing temperature because the specimen austenized at the higher temperature underwent a slower reverse transformation in the early stage of intercritical annealing. The slowed kinetics of the reverse transformation with increasing austenizing temperature was attributed to the reduction in area of block boundaries which provide nucleation sites for the reverted γ. The widths of the α and γR laths were almost independent of the austenizing temperature. The partitioning of Mn and C atoms from α into γR laths became active with increasing austenizing temperature, resulting in a more stable γR. The specimen austenized at higher temperature exhibited a lower strain hardening rate (SHR) due to the less active transformation-induced plasticity (TRIP) in γR with the higher phase stability. The ultimate tensile strength decreased with increasing austenizing temperature because the SHR was lowered by the less active TRIP with increasing austenizing temperature. The uniform elongation increased with increasing austenizing temperature due to delayed necking caused primarily by the flow stress, which dropped with increasing austenizing temperature.

The size effect of initial martensite constituents on the microstructure and tensile properties of intercritically annealed Fe–9Mn–0.05C steel

Tensile properties and deformation mode of Si-added Fe-18Mn-0.6C steels

Recently, Fe-Mn twinning-induced plasticity steels with an austenite phase have been the course of great interest due to their excellent combination of tensile strength and ductility, which carbon steels have never been able to attain. Nevertheless, twinning-induced plasticity steels also exhibit a trade-off between strength and ductility, a longstanding dilemma for physical metallurgists, when fabricated based on the two alloy design parameters of stacking fault energy and grain size. Therefore, we investigated the tensile properties of three Fe-Mn austenitic steels with similar stacking fault energy and grain size, but different carbon concentrations. Surprisingly, when carbon concentration increased, both strength and ductility significantly improved. This indicates that the addition of carbon resulted in a proportionality between strength and ductility, instead of a trade-off between those characteristics. This new design parameter, C concentration, should be considered as a design parameter to endow Fe-Mn twinning-induced plasticity steel with a better combination of strength and ductility.

Design for Fe-high Mn alloy with an improved combination of strength and ductility

Sukjin Lee

Papers

Coupled strengthening in a medium manganese lightweight steel with an inhomogeneously grained structure of austenite

Pitting corrosion behavior in advanced high strength steels

The size effect of initial martensite constituents on the microstructure and tensile properties of intercritically annealed Fe–9Mn–0.05C steel

Tensile properties and deformation mode of Si-added Fe-18Mn-0.6C steels

Design for Fe-high Mn alloy with an improved combination of strength and ductility