基于对625℃超超临界汽轮机转子用钢COST-FB2的迫切需求，为促进我国高端装备制造业急需关键材料国产化进程。针对该类材料在电渣重熔过程中B和N元素含量需严格控制，Al、Si和O等不易控制在目标范围内以及热处理过程中需消除组织遗传性、改善组织均匀性等关键共性问题，建立基于提升材料组织稳定性和力学性能的合金成分优化设计准则和调控理论。建立基于精确控制钢液的硼含量及其他元素含量的渣系组元选配原则，并揭示渣系组元对重熔钢液成分的影响规律。阐明渣系组元对表面张力的影响规律，建立渣系组元与表面张力之间的定量关系，掌握FB2钢电渣重熔过程纯净度控制工艺理论。明晰热处理工艺对FB2钢组织和性能的影响机理，掌握能够获得组织均匀化的FB2大型转子锻件热处理工艺调控方法。研究成果将突破汽轮机转子用FB2钢电渣重熔和热处理过程的关键共性科学与技术问题，为加速国产化进程、推动批量稳定化生产提供技术支撑。

Based on the urgent requirement of 625℃ ultra-supercritical thermal power unit for steam turbine rotor steel COST-FB2 and for the primary problems such as the content of B N, Al, Si and O should be strictly controlled in the process of electroslag remelting and in the heat treatment process the heredity of structure should be eliminated and improves the homogeneity of structure. So the solutions are to reveal the optimum design criterion and control theory of alloy composition for properties; the selection and control theory of slag system components based on precise control of boron content and other elements content in molten steel; the influence law of slag system components on the composition of molten steel; the influence law of slag system components on surface tension; the quantitative relationship between slag system components and surface tension; the theory of purity control in steel during electroslag remelting process; the influence mechanism of heat treatment process on the structure and properties of FB2 rotor steel and the control method of heat treatment process for FB2 large rotor forgings with homogeneous structure is mastered. The research results will break through the key common scientific and technical problems in the process of electroslag remelting and heat treatment of steam turbine rotor steel COST-FB2, and provide technical support for accelerating the process of localization and promoting batch stabilization production.