A cryogenic ultra-strong and ductile steel induced by stable nanoscale dual-phase structure

To obtain ultra-high strength with guaranteed ductility, stable nanolamellar austenite packed with high densities of dislocations and nanotwins is inserted into nanolamellar martensite. An ultra-high yield strengths of 1.6–2.2 GPa at room temperature and 1.94–2.5 GPa at liquid nitrogen temperature w...

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Bibliographic Details
Published in:Journal of materials science 2023-09, Vol.58 (33), p.13476-13487
Main Authors: He, Qiong, Yang, Bo, Wang, Mingsai, Guo, Fengjiao, Zhang, Chao, Zhai, Yu, Wang, Qingyuan, Cao, Wenquan, Huang, Chongxiang
Format: Article
Language:English
Subjects:
Alloys
Austenite
Carrying capacity
Characterization and Evaluation of Materials
Chemistry and Materials Science
Classical Mechanics
Crystallography and Scattering Methods
Dislocation density
Dual phase steels
Elongation
Hardening rate
Heat treating
High strength
Liquid nitrogen
Low temperature
Martensite
Materials Science
Metals & Corrosion
Polymer Sciences
Room temperature
Solid Mechanics
Solid phases
Solid solutions
Solution strengthening
Strain hardening
Temperature
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Summary:To obtain ultra-high strength with guaranteed ductility, stable nanolamellar austenite packed with high densities of dislocations and nanotwins is inserted into nanolamellar martensite. An ultra-high yield strengths of 1.6–2.2 GPa at room temperature and 1.94–2.5 GPa at liquid nitrogen temperature were obtained in the steel, which is combined with good uniform elongation of 4–9%. The designed steel is shaped with the combination of solid solution strengthening, lamellar boundary strengthening and dislocation strengthening. The nanostructure is stabilized by C distribution, and in this way the stress–strain carrying capacity of martensite and austenite is increased, thus ensuring ultra-high strength. In addition, the generation of TRIP effect at low temperatures ensures the realization of strain-hardening rate and uniform elongation at ultra-high strength. Therefore, the nanolamellar martenite-austenite microstructure and strong carbon partitioning through martensite and austenite is considered as a fundamental guarantee for the ultra-high strength and toughness. Our results provide an optional strategy for the development of new ultra-strong alloys for low-temperature applications.
ISSN:0022-2461
1573-4803
DOI:10.1007/s10853-023-08857-x