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

从快感生放射性衰变（FIRD）和非磁性的角度来看，高锰铬奥氏体钢被认为是一种重要的高温结构材料。本课题的目的是为开发未来聚变堆第一壁结构材料FIRD材料，对12%Cr-15%Mn奥氏体不锈钢的组织和力学性能进行基础性研究，并与JPCA和JFMS标准材料的性能进行比较。研究了V、Ti、Ta等合金元素对合金力学性能的影响。细小的VN和Ti（C，N）析出相使高温强度显著提高。C含量为0.1 ~ 0.2%时，晶界上形成粗大的<23>M_C_6型碳化物，使低温韧性下降，导致沿晶断裂。添加0.2%N或更多的N能有效地抑制晶界上粗大碳化物的生成，显著提高合金的持久塑性。此外，应研究V、Ti和Ta添加的最适当组合。

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.