纳米结构CLAM钢超纯净熔炼基础及多尺度第二相耦合强化机制

CLAM steel (China Low Activation Martensitic steel) is the first choice for the future fusion demonstration reactor and fusion power reactor with independent intellectual property rights in China. Its performance is equal to the foreign production RAFM (Reduced Activation Ferritic/Martensitic), but the cleanliness and high temperature performance of them are poor. In response to the above problems, the applicant proposes a new CLAM steel with titanium and zirconium added. The metallurgical thermodynamics mechanism of reaction among Ti, Zr, Ta, O, C and N, and the critical thermodynamic conditions for the formation of reaction products will be studied. Then the exploration and development on the ultra-clean remelting process theory for obtaining micron, submicron-level inclusions and ultra-cleanliness with "VIM-IESR/VAR" process will be done. Researches on forging and heat treatment will be carried out to study the collaborative strengthening mechanism of pinning and dislocation provided by the micron, submicron inclusions and nano-precipitates in the steel. And to explore the control theory and method of microstructure and properties refinement of CLAM steel with high proportion of MX-type precipitates. The final purpose is developing a new generation of high-cleanliness, high-performance nano-structure CLAM steel between CLAM and ODS, and getting the systematic metallurgical process theory.

CLAM钢是我国具有自主知识产权的未来聚变示范堆和聚变动力堆的首选结构材料，其性能与国外RAFM钢的性能相当，但他们都存在纯净度不高和高温性能差等问题。针对上述问题，申请者提出建立添加Ti、Zr的CLAM钢新成分体系，研究钢中Ti、Zr、Ta等元素与O、C、N等元素反应的冶金热力学机理和反应产物生成的临界热力学条件，探索开发采用“VIM-IESR/VAR”工艺获得微米、亚微米级夹杂物及高纯净度的超纯净熔炼工艺理论；再开展锻造及热处理研究，研究在钢中形成的微米-亚微米-纳米尺度的三维质点结构对晶界钉扎和阻碍位错的强韧化机制，探索获得高比例MX类纳米级析出物的CLAM钢组织和性能精细化控制理论及方法。最终开发出介于CLAM与ODS之间的新一代高纯净、高性能纳米结构CLAM钢，并形成系统的冶金工艺理论。

CLAM钢是我国具有自主知识产权的未来聚变示范堆和聚变动力堆的首选结构材料，但存在纯净度不高和高温性能差等问题。项目针对任务书的研究目标，采用理论计算并结合实验室实验研究了钢液中Zr、Ti等元素与O、S等元素反应的热力学机理和反应产物生成的临界热力学条件，以及氧化物临界形核半径等。分别采用真空感应炉和真空感应+电渣重熔工艺流程制备了Ti-Zr纳米结构CLAM钢。研究了不同冶炼、锻造和热处理(含轧制)工艺对CLAM钢的洁净度、夹杂物和力学性能的影响。在热力学计算的指导下分别设计了感应熔炼和电渣重熔纳米结构CLAM钢正－回火工艺，并通过中间热处理工艺和TMP/T工艺对纳米结构CLAM钢微观组织、钢中M23C6和MX等第二相及力学性能进行了调控及其机理研究。所制备的纳米结构CLAM钢屈服强度为657~659 MPa，抗拉强度为772~775 MPa，伸长率为25.4%~ 25.5%，室温冲击功为332~339 J，DBTT为−93~−103℃；TMP工艺处理钢时效1500 h后，屈服强度为572~573 MPa，抗拉强度为701~713 MPa，伸长率为24.5%~25.5%，室温和高温性能均有大幅提升。项目形成了相关冶金工艺理论，为纳米结构CLAM钢的工业化制备奠定了坚实的理论基础。. 项目完成了项目预期研究目标，并达到了预期研究成果指标。项目的主要成果为：项目获得授权国家发明专利3项。共发表第一标注论文21篇，其中，SCI收录14篇，EI收录1篇，会议论文3篇。培养毕业研究生3名，其中博士1名，硕士2名。