| 摘要 |
PURPOSE:To improve the resistance to intercrystalline damage by a method wherein heat transfer pipe for steam generator employed in pressurized water reactor is made of Ni-base alloy containing the specified amount of Cr and Ni and constituted so as to give residual compressive stress to at least some portion of its outer surface layer part. CONSTITUTION:Heat transfer pipe for steam generator is made of Ni-base alloy containing 14-35% by weight of Cr and not least than 30% by weight of Ni and constituted so as to give residual compressive stress to some portion of its outer surface layer part. Concretely, in order to give residual compressive stress to some portion of the outer surface layer part of Ni-base alloy pipe, said portion is held within the temperature range of 300-600 deg.C for no less one minute by heating from the inside surface while being cooled by water from the outside surface and, after that, the heating is stopped. Or, residual compressive stress is given to the surface layer part by holding the Ni-base alloy pipe within the temperature range of 600-800 deg.C for no less than 0.5min in order to precipitate chrome carbide on the boundaries between the crystal grains and, after that, cooling with water. |
