超高强度结构钢的研究及发展

Research and application progress of ultra-high strength structural steel

超高强度结构钢是一种具有1200 MPa以上屈服强度以及良好的断裂韧性和延性的钢,被广泛应用于航空、航天、舰船、海洋工程、工程机械等高端制造领域。同时保持超高强度、高塑性和高韧性是超高强度结构钢研究领域中的关键难题。本文归纳总结了典型低合金超高强度钢、二次硬化超高强度钢和马氏体时效钢的发展历程和研究进展,重点介绍了超高强度结构钢的强韧化和延性机制。超高强度结构钢的超高强度是通过高密度位错马氏体基体中析出大量纳米级碳化物、金属间化合物或富Cu相而获得;优异的断裂韧性是通过马氏体板条、区块和亚稳态奥氏体的多相多尺度层状微观结构设计来实现;而高塑性的关键是在高密度可移动位错基体中引入亚稳态奥氏体形变诱导塑性(TRIP)效应。高密度位错马氏体基体、多相多尺度结构和亚稳态奥氏体TRIP效应的研究进展有望突破超高强度结构钢的强度、塑性、韧性三者不可兼得的瓶颈。

Ultra-high strength structural steel is a kind of steel with yield strength of more than 1200 MPa and excellent fracture toughness and ductility, and it is widely used in manufacturing fields such as aviation, aerospace, naval vessels, offshore engineering and engineering machinery. It is a key problem in the research field of ultra-high strength structural steel to maintain ultra-high strength, high ductility and high toughness at the same time. In this paper, the development and research progress of typical low alloy ultra-high strength steel, secondary hardening ultra-high strength steel and maraging steel are summarized, and the strengthening, toughening and ductility mechanism of ultra-high strength structural steel are introduced. The ultra-high strength of the ultra-high strength structural steel is obtained by precipitating a large number of nanoscale carbides, intermetallic compounds, or Cu-rich phases in the high-density dislocation martensite matrix;the excellent fracture toughness is achieved by the design of multi-phase and multi-scale layered microstructure of martensite laths, blocks and metastable austenite;and the key to high ductility is the introduction of metastable austenite in the high-density removable dislocation matrix. The research progress of the martensite with high dislocation density, the multi-phase multi-scale microstructure and the metastable austenite TRIP effect is expected to break through the trade-off between strength and toughness or ductility for ultra-high strength structural steel.