含铜纳米相强化钢中纳米相控制及其强化和韧化机理研究

With the development and construction of shipbuilding, deep-water drilling rigs etc., it is extremely urgent to develop high strength low alloy steels with high toughness, suitable weldability and weathering ability. Traditionally-designed steels are usually strengthened by carbon, grain refinement, nitride/carbide etc. In general, however, these strengthening methods sacrifice the toughness and weldability during increasing the strength. In this proposal, newly-developed nanoscale Cu enriched-precipitates-strengthened steels will be selected as research objects. The effects of the composition and thermo-mechanical control process (TMCP) on the formation of nanoscale precipitates and the matrix will be investigate by tailoring the size, morphology, structure, spatial distribution of precipitates and the evolution of the matrix microstructure. The thermodynamic and kinetics of the formation of nanoscale Cu enriched precipitates and the strengthening mechanisms of these precipitates will be elucidated. The effects of precipitate strengthening and matrix structure on the yielding-to-tensile ratio will also be clarified. These studies will provide fundamental information to the steel composition design and the processing optimizations for the structure steel development.

随着我国在舰船、深海钻井平台等基础设施方面的发展建设，亟需大量高强度、高韧性同时具有高焊接性能和耐候性的低合金结构钢。传统钢的强化方式主要是利用碳强化、合金强化、细晶强化以及碳、氮化物弥散强化等方式。然而这些强化方式在提高钢的强度的同时，不可避免地牺牲韧性和焊接性能。本项目选用新型含铜纳米相强化高强度低合金钢为研究目标，通过成分设计和热机械处理工艺控制等措施，实现对纳米相尺寸、形态、结构、分布等参数的控制，同时兼顾对基体相显微结构的控制。对纳米相的形成及其对力学性能的影响进行深入认识，揭示纳米相形成热力学和动力学过程。阐明纳米相强化钢中纳米相强化和韧化机理以及强度提高对屈强比的影响机制。解决纳米相强化钢制备过程中成分优化、组织调控的关键技术和措施，为开发出高强度、高韧性具有优异的焊接性能的低屈强比低合金舰船结构提供理论基础。

传统钢的强化方式主要是利用碳强化、合金强化、细晶强化以及碳、氮化物弥散强化等方式。然而这些强化方式在提高钢的强度的同时，不可避免地牺牲韧性和焊接性能。设计新的强化相结构并理解其强化机制对于开发和优化新型纳米相强化高强钢具有重要的科学价值和意义。本项目选用新型含铜纳米相强化高强度低合金钢为研究目标，通过成分设计和热机械处理工艺控制等措施，实现了对纳米相尺寸、形态、结构、分布等参数的控制，同时兼顾对基体相显微结构的控制。研究了不同合金体系中（纳米相强化低合金高强度钢和含铜纳米相强化止裂钢）纳米相随成分和处理工艺的演变，阐明合金了复杂纳米相的形核、长大热、动力学机制。阐明了纳米相强化钢中纳米相强化和韧化机理以及强度提高对屈强比的影响机制。解决了纳米相强化钢制备过程中成分优化、组织调控的关键技术和措施，并开发出高强度、高韧性具有优异的焊接性能的低屈强比低合金舰船结构钢。