Abstract: There is provided a welding material used for welding of SUS310 stainless steel base metal that contains at least one of Nb and V and is excellent in intergranular corrosion resistance, the chemical composition of the welding material consisting, by mass percent, of C: 0.02% or less, Si: 2% or less, Mn: 2% or less, Cr: 26 to 50%, N: 0.15% or less, P: 0.02% or less, S: 0.002% or less, and Ni: a content percentage satisfying [5?Ni?Cr?14], and the balance of Fe and impurities. Also, there is provided a welding joint of an austenitic stainless steel, which consists of the base metal and a weld metal formed by using the welding material.

Abstract: A nickel material, which comprises by mass percent, C: 0.003 to 0.20% and one or more elements selected from Ti, Nb, V and Ta: a total content less than 1.0%, the contents of these elements satisfying the relationship specified by the formula of “(12/48) Ti+(12/93) Nb+(12/51) V+(12/181) Ta—C?0”, with the balance being Ni and impurities, does not deteriorate in the mechanical properties and corrosion resistance even when it is used at a high temperature for a long time and/or it is affected by the heat affect on the occasion of welding. Therefore, it can be suitably used as a member for use in various chemical plants including facilities for producing caustic soda, vinyl chloride and so on. Each element symbol in the above formula represents the content by mass percent of the element concerned.

Abstract: There is provided a welding material used for welding of SUS310 stainless steel base metal that contains at least one of Nb and V and is excellent in intergranular corrosion resistance, the chemical composition of the welding material consisting, by mass percent, of C: 0.02% or less, Si: 2% or less, Mn: 2% or less, Cr: 26 to 50%, N: 0.15% or less, P: 0.02% or less, S: 0.002% or less, and Ni: a content percentage satisfying [5?Ni?Cr?14], and the balance of Fe and impurities. Also, there is provided a welding joint of an austenitic stainless steel, which consists of the base metal and a weld metal formed by using the welding material.

Abstract: The high-strength Ni-based alloy tube for nuclear power use consists, by mass percent, of C: 0.04% or less, Si: 0.10 to 0.50%, Mn: 0.05 to 0.50%, Ni: 55 to 70%, Cr: more than 26% and not more than 35%, Al: 0.005 to 0.5%, N: 0.02 to 0.10%, and one or more kinds of Ti: 0.01 to 0.5% and Nb: 0.02 to 1.0%, the balance being Fe and impurities. For this alloy tube, the grain size is as fine as grain size No. 6 or higher in JIS G 0551. It is preferable that the high-strength Ni-based alloy tube be manufactured by the process of preparing a Ni-based alloy stock through a remelting process, hot forging, heating to 1000 to 1160° C., hot extruding at a working ratio such that an extrusion ratio is 4 or higher, and performing solution annealing and thermal treatment.

Abstract: [Problem to be Solved] There are provided a high-strength Ni-based alloy tube for nuclear power use having uniform high temperature strength throughout the overall length of tube and a method for manufacturing the same. [Solution] The high-strength Ni-based alloy tube for nuclear power use consists, by mass percent, of C: 0.04% or less, Si: 0.10 to 0.50%, Mn: 0.05 to 0.50%, Ni: 55 to 70%, Cr: more than 26% and not more than 35%, Al: 0.005 to 0.5%, N: 0.02 to 0.10%, and one or more kinds of Ti: 0.01 to 0.5% and Nb: 0.02 to 1.0%, the balance being Fe and impurities. For this alloy tube, the grain size is as fine as grain size No. 6 or higher in JIS G 0551. It is preferable that the high-strength Ni-based alloy tube be manufactured by the process described below: preparing a Ni-based alloy stock through a remelting process, hot forging, heating to 1000 to 1160° C., hot extruding at a working ratio such that an extrusion ratio is 4 or higher, and performing solution annealing and thermal treatment.

Abstract: A method for manufacturing a Ni-based alloy article which elutes little Ni even when used in a high-temperature water environment for a long period comprises heating the Ni-based alloy in a carbon dioxide-containing atmosphere for a set period of time at an elevated temperature to form an oxide film comprising chromium oxide on a surface thereof. Using carbon dioxide as an oxidizing gas produces an oxide film of generally uniform thickness along a length of the article being treated so that resistance to nickel elution is more uniform over the entire article.

Abstract: A nickel material, which comprises by mass percent, C: 0.003 to 0.20% and one or more elements selected from Ti, Nb, V and Ta: a total content less than 1.0%, the contents of these elements satisfying the relationship specified by the formula of “( 12/48)Ti+( 12/93)Nb+( 12/51)V+( 12/181)Ta—C?0”, with the balance being Ni and impurities, does not deteriorate in the mechanical properties and corrosion resistance even when it is used at a high temperature for a long time and/or it is affected by the heat affect on the occasion of welding. Therefore, it can be suitably used as a member for use in various chemical plants including facilities for producing caustic soda, vinyl chloride and so on. Each element symbol in the above formula represents the content by mass percent of the element concerned.

Abstract: A method for manufacturing a Ni-based alloy article which elutes little Ni even when used in a high-temperature water environment for a long period comprises heating the Ni-based alloy in a carbon dioxide-containing atmosphere for a set period of time at an elevated temperature to form an oxide film comprising chromium oxide on a surface thereof. Using carbon dioxide as an oxidizing gas produces an oxide film of generally uniform thickness along a length of the article being treated so that resistance to nickel elution is more uniform over the entire article.

Abstract: A method of heat treatment for an efficient forming of two-layered oxide film on the inside surface of a Ni-base alloy tube. The oxide film suppresses the Ni release in a high-temperature water environment. At least two gas supplying devices are provided on the outlet side of a continuous heat treatment furnace; or one gas supplying device is provided respectively on the outlet side and the inlet side thereof. The tube is put into the furnace while supplying an atmospheric gas into the tube from the front end of the tube moving direction with one of these gas supplying devices and a gas introducing pipe, which is arranged inside the furnace, and this tube is maintained at 650 to 1200° C. for 1 to 1200 minutes. The atmospheric gas consists of hydrogen or a mixture of hydrogen and argon, whose dew point is in a range of from ?60° C. to +20° C.

Abstract: A method of heat treatment for an efficient forming of two-layered oxide film on the inside surface of a Ni-base alloy tube. The oxide film suppresses the Ni release in a high-temperature water environment.

Abstract: (1) A nickel-base alloy product having, on the surface thereof, an oxide film comprising at least two layers, namely a first layer mainly composed of Cr2O3 and having a chromium content of not less than 50% relative to the total amount of metal elements and a second layer occurring outside the first layer and mainly composed of MnCr2O4, wherein the grain size of Cr2O3 crystals in the first layer is 50 to 1,000 nm and the total oxide film thickness is 180 to 1,500 nm. (2) A method of producing the nickel-base alloy product as specified above under (1) which comprises subjecting a nickel-base alloy product to oxide film formation treatment by maintaining the same at a temperature of 650 to 1,200° C. in a hydrogen atmosphere or hydrogen-argon mixed atmosphere showing a dew point of −60° C. to +20° C. for 1 to 1,200 minutes.

Abstract: (1) A nickel-base alloy product having, on the surface thereof, an oxide film comprising at least two layers, namely a first layer mainly composed of Cr2O3 and having a chromium content of not less than 50% relative to the total amount of metal elements and a second layer occurring outside the first layer and mainly composed of MnCr2O4, wherein the grain size of Cr2O3 crystals in the first layer is 50 to 1,000 nm and the total oxide film thickness is 180 to 1,500 nm.