高强度高韧性是钢铁材料主要发展方向和研究热点。针对“如何使金属材料在获得超高强度的同时保持良好塑性变形能力”这一科学问题，采用以超快冷为核心的新一代TMCP轧制技术，通过两相区退火及等温热处理，制备晶粒尺寸、奥氏体体积分数与形态、析出物尺寸与分布可控的超高强TWIP/TRIP钢。通过纳米尺度片状奥氏体可以促进稳态马氏体相变，结合孪生的动态Hall-Petch效应、析出强化效应等复合强韧化手段，改善超高强TWIP/TRIP钢的加工硬化性能。系统研究纳米尺度奥氏体的体积分数和形态对具有不同晶粒尺寸的TWIP/TRIP钢在复杂应力下的微观结构及力学性能变化的影响规律，提出实现TWIP/TRIP钢强度与塑性最佳匹配的技术措施。.该研究取得的成果将为高强、超塑、成型性能更优的新一代轻量化汽车用钢的研发提供参考，为工程材料的使役性能预估提供理论参考，对丰富孪生及相变领域材料学理论具有重要的学术价值。

The main target and research focus of steel development is how to achieve both the higher strength and better toughness simultaneously. Based on the scientific issue how simultaneously to keep a good ductility and high strength of metallic materials, ultrahigh-strength steels will be prepared by tailoring grain size, content and morphology of austenite, size and distribution of precipitates. The preparation methods mainly consist of a continuous rolling accompanied with the new generation TMCP(Thermo-Mechanical-Controlled Processing) technique, with subsequently intercritical annealing and austempering holding. It is expected to promote the work-hardening ability of ultrahigh-strength steel by the comprehensively strengthening and toughening effects, resulting from grain refinement (Hall-Petch relationship), transformation-induced-plasticity (TRIP), precipitation hardening and twinning-induced-plasticity (TWIP). By investigating the deformation behavior of ultrahigh-strength steels under complex conditions/environment, the main objective of this project is intended to explore relationship between mechanical properties and the volume fraction along with the morphology of nanoscale austenite in TWIP/TRIP steels with various grain sizes. It is predicted that some breakthroughs will be achieved through a successful execution of this program in the following several aspects:. (1) proposing a new method to improve a better trade-off between the strength and ductility of TWIP/TRIP steels; (2) providing a significantly experimental and theoretical basis for the development of a new generation of steels, which might be potentially used as the frame of the new generation of light-weight vehicles. The investigated steels are intended to possess excellent properties, including ultrahigh strength, good ductility, high security, and good formability, enhanced energy-absorption-capacity, and low specific gravity; (3)shedding a light on enriching the theories related to twinning and transformation processes of metallic materials, which has significantly important academic value; (4) providing a reference for the deformation of metallic materials with twin microstructures and metastable austenite. A new microstructure-based damage theory will be developed to predict accurately the service performance and deformation damage of polycrystalline materials under the complex service conditions. This is extremely important for both theory and practice to the engineering application and requirement of key materials with ultrahigh strength.