基于应变诱导Laves相高温析出的超级铁素体不锈钢再结晶组织织构调控机理

目前，常用“高温加热（～1180℃）+快速冷却”工艺消除超级铁素体不锈钢中σ、χ、Laves相脆性。但高温加热易导致晶粒粗化和γ-纤维织构弱化，恶化材料的韧性与成形性能。本项目基于Laves相脆性具有尺寸效应这一研究发现，提出采用低温加热（1000～1060℃），在避开σ、χ相析出温度区间的同时，利用应变诱导纳米级Laves相单独析出来细化再结晶晶粒并强化γ-纤维织构。研究变形组织对Laves相形核和长大的影响规律，阐明应变诱导Laves相析出机制；探究应变诱导Laves相析出动力学与再结晶动力学间的次序关系，针对不同动力学关系，建立Laves相析出控制方法；分析预析出Laves相对再结晶行为与织构演变的影响规律，揭示再结晶形核和长大、γ-纤维织构起源和发展机理，构建基于Laves相析出的再结晶组织织构调控模型，发展“低温退火”制备新技术，为超级铁素体不锈钢工业化生产提供方法与理论支撑。

High temperature annealing (~1180℃) and rapid cooling processes are usually used to inhibit the brittle phase precipitation of σ, χ and Laves phase aiming at ensuring the toughness of super-ferritic stainless steels. While this process leads far too easily to a result of grain coarsening and γ-texture weakening and further result in a decrease of plasticity and toughness. Based on the finding that the Laves phase embrittlement is dependent on its sizes, this project proposes to use a low temperature annealing process (1000~1060 ℃) to make the nanoscale Laves phase be formed in the deformed microstructure by a methods named as the strain inducing Laves phase precipitation, during which the σ and χ phases do not be precipitated, and further to refine the recrystallization grains and to strengthen the γ-fiber texture, then finally to improve the plastic and forming properties. By analyzing the effect of deformation microstructure on the nucleation and growth behavior of Laves, the micro-mechanism of Laves phase precipitation at higher temperature induced by strain will be clarified. After comparing the relationship between the strain-induced precipitation kinetics of Laves phase and the recrystallization kinetics of deformed ferrite microstructure, then the control method will be also clarified by considering different kinetics relationships. After analyzing the effects of pre-precipitated Laves phase on recrystallization behavior and texture evolution, the mechanism both of recrystallization nucleation and growth, and of the γ-fiber texture origin and development will be further revealed, and the regulation theory of recrystallization microstructure and texture based on Laves phase precipitation behavior will be finally established. The research results of this project would provide a method and theory support for industrial production of super-ferritic stainless steel by low temperature annealing process.