• The dissimilar joints of F82H and SUS316L were produced by the fiber laser welding. • F82H and SUS316L plates were direct butt joined by the friction stir welding. • Yield stress of joint joined by fiber laser welding was the same as that of SUS316L. • The proportional limit of FSW joint was larger than that of fiber laser joint. • Any notable defects were not observed after the creviced bent beam tests. A well perceived reduced activation ferritic/martensitic steel F82H is one of the most candidate structural materials for a water-cooled cylindrical blanket of Japan’s DEMOnstration fusion reactor (JA DEMO) where the water-cooling pipe made by F82H should be connected with the cooling pipe of JA DEMO which is planned to be produced by the austenitic stainless steel SUS316L. In order to ensure the safety and reliability of the blanket for JA DEMO, it is necessary to understand the high temperature water corrosion behavior of F82H/SUS316L dissimilar joint. In this research, F82H and SUS316L plates were butt welded using the fiber laser welding where Inconel 625 was employed as the inter layer to prevent the martensitic transformation of weld metal. In addition, the friction stir welding (FSW) was applied for direct butt joint between F82H and SUS316L plates. The tensile tests using SS-J3 sub-size specimen of these dissimilar joints indicate the enough weldability or joinability for employing the cooling pipe of JA DEMO. Moreover, the basic corrosion behavior through the creviced bent beam stress corrosion cracking test also proves the applicability of both fiber laser welding and FSW for producing F82H/SUS316L dissimilar joint which is needed for actualizing the future fusion reactor.
Serizawa et al. (Thu,) studied this question.