To address global environmental concerns and reduce carbon dioxide emissions, countries worldwide are prioritizing the development of green, eco-friendly, and low-carbon energy sources. This emphasis has led to the growing importance of promoting clean energy industries like hydrogen energy and natural gas. These gases are typically stored and transported at cryogenic temperatures, making ultra-low temperature alloys indispensable as essential materials for the storage and transportation of liquid gas energy. With the temperature decreasing from room temperature (RT) to liquid nitrogen temperature (LNT), the dominant deformation mechanism in high-manganese steels undergoes a transformation from dislocation slip to deformation twinning, resulting in exceptional cryogenic mechanical properties. Consequently, high-manganese steel has emerged as an excellent material candidate for cryogenic applications. This report focuses on establishing the composition of high-manganese steel suitable for cryogenic applications and provides a comprehensive review of its microstructure and mechanical properties at both RT and LNT. Furthermore, it offers a prospective outlook on the future development of cryogenic high-manganese steels.

Fe-30Mn-0.05C steel specimens with cold-rolled, partially recrystallized, fine-grained, and coarse-grained microstructures were fabricated by means of 80% cold rolling followed by annealing at 550–1000 °C. The initial and deformed microstructures were characterized, and the Charpy impact properties were tested at room temperature (RT) and liquid nitrogen temperature (LNT). It was found that the Charpy absorbed energy increased with the annealing temperature, while the specimens showed different trends: parabolic increase at RT and exponential increase at LNT, respectively. Compared with the fully recrystallized specimens, those with a partially recrystallized microstructure exhibited lower impact energy, especially at LNT. This was because cracks tended to nucleate and propagate along the recovery microstructure where stress concentration existed. The grain size played an important role in the twinning behavior and impact properties. High Charpy impact energy (~320 J) was obtained in the coarse-grained specimen having the grain size of 42.1 μm at both RT and LNT, which was attributed to the activation of high-density deformation twinning. However, deformation twinning was inhibited in the specimen with the average grain size of 3.1 μm, resulting in limited work hardening and lower impact energy.

The Charpy impact toughness of single-phase austenitic Fe-32Mn-0.6C steel was systematically investigated across a wide temperature spectrum from 25 °C to −196 °C using Charpy V-notch impact tests. The material exhibited a remarkable temperature dependence of impact energy, decreasing dramatically from 120 J at ambient temperature (25 °C) to 13 J under cryogenic conditions (−196 °C). Notably, a steep transition in impact energy occurred within the critical temperature window of −100 °C to −150 °C. Microstructural analysis revealed that synergistic effects of high strain rates and low temperatures significantly restrict dislocation slip and multiplication mechanisms, while also suppressing deformation twinning activation. This restricted plasticity accommodation mechanism fundamentally differs from the deformation characteristics reported in conventional low-carbon high-manganese steels and other face-centered cubic (FCC) alloy systems.