基于亚稳奥氏体温变形和相变调控的3.0GPa超级高强高韧钢的制备及其强韧化机理研究

超级高强钢主要应用于军工国防装备、航空器械的防护、民用重大装备、重要设备及先进工具等相关领域，当今世界各国都在加大超高性能钢的研发力度，我国已把先进高性能钢铁研发列为国家重大发展方向。高强度化始终是钢铁发展的主题。本项目拟开展有关超级高强钢的制备技术和强韧化机理研究。超级高强度高韧性合金钢的制备工艺及其强韧化机制研究具有重要的学术价值和现实意义。本项目旨在基于“奥氏体稳定化成分设计-亚稳奥氏体温变形-相变调控”的一体化工艺技术，开发并制备2500MPa以上级低成本、大尺寸、超细组织结构的超级高强度低合金钢。通过对不同温变形处理工艺下的材料的微观组织演变、力学性能变化及拉伸变形行为的分析，揭示超级高强钢的强化、韧化机制和应变硬化机理；通过对变形亚稳奥氏体的相变热力学和动力学的研究，揭示微纳结构亚稳奥氏体分解的相变和析出的规律，并建立纳米晶至粗晶宽广尺度范围下的强度、硬度和有效晶粒尺寸之间的相关关系。最后基于该制备工艺的进一步优化，开发一种新型超级高强度高韧性低合金钢，拉伸性能满足：YS≥2500MPa，UTS≥3000MPa，EL≥5.0%。本项目的超级高强钢的制备工艺及方法、相关研究结果和结论对我国新一代高性能高品质钢材的开发与应用具有指导作用。开发面向未来的3.0GPa及以上抗拉强度的先进超级高强钢，可以为国家的新一代轻量化重型装备、重要工程建设、战略新兴产业及国防武器等领域中，以钢铁为主的关键部件提供相关依据与支撑，提升我国在钢铁行业和国际研究领域的地位和影响。

Research and development of low cost, ultra-high strength and high ductility lowalloy steels has important academic value and practical significance. This project aims to develop an integrated processing technique based on “Composition design of Austenite stabilization– Severely warm-rolling of metastable austenite– Phase-transformation manipulating” to produce super-high strength (2.5GPa and above) low-alloy steel with low-cost, large-size and ultrafine-structures. Through the test and analysis of the microstructure evolution and mechanical properties of materials under different warm-deformation processes, as well as the study of thermodynamics and kinetics of the deformed metastable austenite transformation , the evolution law of micro-/nano-structured metastable austenite decomposition is revealed , and the relationship between strength, hardness and effective grain size is stablished in a broad grain-size ranged from nano-grains with ten nanometers to coarsen-grains with tens of microns. Based on these analyses, the strengthening- toughening mechanism and strain-hardening behavior of the super-high strength low alloy steel are revealed. Upon these processing optimization, a new super-high strength high ductility low alloy steel with tensile properties that meet YS≥2500MPa, UTS≥3000MPa and EL≥5.0% is developed. The fabrication technique and method possibly formed of the super high strength steel, the related research results and conclusions obtained in this project will provide an important guidance for the development and application of the new generation of high-performance and high-quality steels in our country.