梯度结构高强度高韧性钢板的制备及其断裂机理研究

高强度、高韧/塑性是钢铁材料发展的重要方向，调整钢铁材料的微观结构，使其成为梯度变化，可打破原本耦合在一起的材料性能，为大幅提升材料的整体性能和使役性能提供有效途径。项目提出利用轧制-水冷同步耦合的方式制备具有高强度、高韧性的梯度结构厚钢板，研究轧制-水冷同步耦合过程中的动态往复相变和组织细化机理，分析往复变形-冷却与动态再结晶、往复相变、纳米析出之间的耦合作用，建立典型化学成分、热变形和冷却工艺参数与梯度结构层、最终力学性能之间的关系，在实验室条件下制备出具有高强度、高韧/塑性且梯度结构可控的新型钢板；研究不同厚度梯度层和不同晶粒尺寸梯度层的裂纹萌生和扩展规律，分析梯度结构钢板中超细晶/细晶层和粗晶层中的塑性变形特征，获得厚规格钢板梯度结构的断裂机理。项目的研究，可为工业化生产出造船、桥梁、建筑和海洋装备等大型结构制件制造所需求的高强度、高韧性厚钢板提供理论基础和数据支撑。

Steels have been keeping the development towards of high strength, high toughness and high ductility. Adjust the microstructure of steels to gradient structure can break the original coupling in material properties together, and significantly enhance the overall performance of the steel. This project intends to carry out research on preparation high strength and high toughness steel plate with gradient structure by controlled rolling coupling water-cooling process, and the cyclical phase transformation and mechanism of microstructure refinement were also studied. The research will also focus on the coupling mechanism in deformation and water-cooling process to dynamic recrystallization, reciprocating phase transition and nano precipitation. The relationship among the typical chemical composition, thermal deformation and cooling process parameters and the gradient structure layer, as well as the final mechanical properties will be established. We will prepare the high strength, high toughness/ductility and gradient structure controllable new steel plate at the laboratory condition, and analyze the crack initiation and propagation law of different thickness gradient layer and different grain size gradient layer. This study will provide theoretical basis and data support for industrial production of high strength and high toughness heavy steel plates for shipbuilding, bridges, buildings and marine equipment.