Heat treatment method for metal tube for nuclear power plant, batch type vacuum heat treatment furnace used therefor, and metal tube for nuclear power plant processed thereby

摘要

In a heat treatment method for a metal tube for a nuclear power plant, when a plurality of metal tubes for a nuclear power plant housed in a batch type vacuum heat treatment furnace are placed on a metal beam arranged in the longitudinal direction and subjected to heat treatment In addition, the metal tube and the metal beam can be brought into contact with each other via a heat resistant cloth having a thickness of 0.1 to 1.2 mm, thereby suppressing the formation of a scum on the outer surface of the metal tube due to the heat treatment. Coloring on the outer surface of the metal tube can be reduced. In this case, the composition of the metal tube is mass%, C: 0.15% or less, Si: 1.00% or less, Mn: 2.0% or less, P: 0.030% or less, S: 0.030. %: Cr: 10.0-40.0%, Ni: 8.0-80.0%, Ti: 0.5% or less, Cu: 0.6% or less, Al: 0.5% or less, and N : It is preferable to use 0.20% or less, with the balance being Fe and impurities.