(1.The State Key Laboratory for Refractory Material and Metallurgy Jointly-Constructed by Ministry-Province, Hubei Collaborative Innovation Center for Advanced Steels,International Research Institute for Steel Technology, Wuhan University of Science and Technology（2.Hubei Xinyegang Steel Co., Ltd.,
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DOI:
10.7502/j.issn.1674-3962.2015.07.15
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Abstract:
Micro- and nano-structured steels are high-performance structural steels which have a unique combination of ultra-high strength, high ductility and good toughness. The ultra-high strength of these steels is attributed to sub-micro or nanosized ultra-fine martensitic and bainitic structures, while the ductility and toughness is associated with retained austenite. Therefore, it has become an important scientific problem to achieve fine microstructure and excellent mechanical properties by means of adjustment of the retained austenite through controlling the chemical composition and heat treatment etc. Based on the strengthening and toughening mechanism of iron and steel, the refinement of microstructure and reasonable regulation of hard and soft phases are important way to develop a new generation iron and steel material. The recent development of micro- and nano-structured super bainitic steel, Q&P and Q-P-T steels are reviewed and analyzed from the alloy design, heat treatment process and the relationship between microstructure and mechanical properties, wear properties and fatigue properties. Finally some issues on the micro- and nano-structured ultra high strength steels are pointed out for further research and development.