Characterization of non-magnetic Mn-Cr steel as a low induced activation material for vacuum vessels

The JT-60SU (Super Upgrade) program is under discussion at Japan Atomic Ene rgy Research Institute (JAERI). Its design optimization activity requires t he vacuum vessel material to be non-magnetic, very strong and with low indu ced activation. However, there is no suitable material available to fulfill all the requirements. JAERI started to develop a new material for the vacu um vessel together with the Japan Steel Works (JSW). Chemical composition a nd metallurgical processes were optimized and a new steel named VC9, which has the composition of Cr - 16 wt%, Mn - 15.5 wt%, C - 0.2 wt%, and N - 0.2 wt% with non-magnetic single gamma phase, was selected as a candidate mate rial. Here, mechanical properties and weldability of VC9 were examined and the results were compared with those of type 316 or 316L stainless steel. I t was shown that VC9 has good mechanical properties and weldability, (C) 20 00 Elsevier Science B.V. All rights reserved.