第三代先进高强钢（AHSS）是由亚稳奥氏体与高强度相构成的复合结构。已开发的热处理工艺通常始于奥氏体单一相，但后续热处理无法满足既可维持组织精细程度的同时、又充分利用碳和锰元素来共同调控奥氏体的分布和稳定性的需求。针对此问题，申请人提出始于两相组织珠光体、再经短时奥氏体单相区逆转变的热处理流程，制备出结构和强度均满足第三代AHSS需求的伪珠光体钢，但其韧性不足。本项目拟研究该组织中奥氏体/马氏体纳米片层的协调变形机制，阐明奥氏体TRIP效应随应变的演化规律，揭示TRIP效应在加工硬化各个阶段所发挥的作用，明确奥氏体稳定性对伪珠光体变形过程的影响，以期为进一步改进伪珠光体的片层结构、优化热处理工艺参数以及提升其韧性水平提供理论支撑。该项目是对珠光体短时奥氏体逆转变研究的拓展和深化，有望为其发展成为真正可控的生产工艺助力，促进第三代AHSS进一步向低成本高性能的方向发展。

The 3rd generation advanced high strength steel (3rd Gen AHSS) can be regarded as a composite structure composed of metastable austenite and high strength phase. Several developed heat treatment methods are all based on austenite single phase as the starting microstructure, and the following heat treatment steps are usually not able to not only maintain the fine length scale of the microstructure but also use both C and Mn to control the stability of the austenite concurrently. Therefore, we proposed a new method in which the heat treatment started with a two-phase pearlitic microstructure, followed by a short re-austenitization treatment in austenite single phase field. In this way, we created a ghost pearlite structure which met the requirement of the 3rd Gen AHSS from both structure and strength point of view. However, the ductility of ghost pearlite still needs to be improved. In the current project, some further studies relating to the deformation mechanism of ghost pearlite are required, including the cooperative deformation mechanism of austenite and martensite nano-layers, the evolution of TRIP effect of austenite as a function of strain, the effect of austenite TRIP effect on the strain hardening behavior, and the effect of austenite stability throughout the deformation process, in order to optimize the lamellar structure, the heat treatment parameters and finally increase the ductility of the ghost pearlite. This is a continuation of the study on developing a short re-austenitization treatment based on pearlitic structure, which will help us to further understand the ghost pearlite and the new heat treatment method, try to fit this method to the real manufacturing, and eventually propel the development of the 3rd Gen AHSS towards lower cost and higher strength and toughness.