Double-ply-welded bellows of nesting type are used as sealing devices of valves for high-temperature and high-pressure applications, and so far, the same-metal-welded bellows have been used exclusively. In the present investigation, the authors manufactured dissimilar-metal-welded bellows aiming at high corrosion resistance as well as mechanical strength. Namely, highly corrosion-resistant Ni base alloy B is placed on the fluid-contact side and higher-strength Ni base alloy A is placed on the no-fluid-contact side for the purpose of mechanical back-up of Ni base alloy B. As a result of study on its characteristics, it has been found that the welded part of this dissimilar-metal-welded bellows has mechanical strength near that of the Ni base alloy A and the chemical composition is intermediate between Ni base alloys A and B. Furthermore, it was confirmed that this bellows has higher resistance to corrosion than the bellows made of only Ni base alloy A, and has a longer total life than the same-metal-welded bellows made of only Ni base alloy A or B.
