Fundamental research for the development of new high temperature Fe-Cr-Mn alloys.

高锰铬奥氏体钢具有快速诱导放射性衰变（FIRD）和非磁性等特点，是一种重要的高温结构材料。本项目的目的是对12% Cr-15%Mn奥氏体不锈钢的微观结构和力学性能进行基础研究，为未来核聚变反应堆第一壁结构材料FIRD材料的开发提供基础研究，并将这些性能与日本正在研究的核聚变反应堆结构材料JPCAs和JFMS的参考材料进行比较。考察了V、Ti、Ta等合金元素对合金力学性能的改善作用。微量VN和Ti（C，N）的析出明显提高了材料的高温强度。而当c含量为0.1 ~ 0.2%时，在晶界上形成M_<23>C_6型碳化物的极粗析出，使低温韧性变差，导致晶间断裂。添加0.2%及以上的氮能有效抑制粗碳化物在晶界上的扩散，显著提高蠕变断裂延展性。此外，还应研究V、Ti和Ta的最佳添加组合。

High Mn-Cr austenitic steels are considered to be an important high temperature structural material from the point of view of fast induced radioactivity decay(FIRD) and non-magneticity. The objective of the present project is to make a fundmental research on the microstructure and mechanical properties of 12% Cr-15%Mn austenitic stainless steels for the development of FIRD amterial for the first wall structural materials of future fusion reactor and to compare these properties with those of the reference materials of JPCAs and JFMS,which are being investigated for the development of fusion reactor structural materials in Japan.The effects of the alloying elements V,Ti, Ta etc. were investigated to determine the improvement of mechanical properties. Tiny precipitates of VN and Ti(C,N)raised the high-temperature strength considerably. Content of 0.1 to 0.2%C,however, formed very coarse precipitates of M_<23>C_6 type carbide on the grain boundaries, which deteriorated low temperature toughness inducing intergranular fracture. Addition of 0.2%N and more was very effective for the restraining of coarse carbide on grain boundaries and to improve creep-rupture ductility considerably. Furthermore, the most appropriate combination of V,Ti and Ta addition should be investigated.