Nippon Steel Sumitomo Metal Corporation

Sumitomo Metal Industries, Inc.

Nippon Steel Corporation

Osamu Miyahara

Yasuhiro Masaki

Manabu Kanzaki

Kazuyuki Kitamura

Toshihiro Imoto

Hirokazu Okada

Hiroyuki Hirata

Yasuyoshi Hidaka

Kaori Kawano

Hiroyuki Semba

Atsuro Iseda

Hiroyuki Anada

Akihiro Uehira

Masaaki Igarashi

Kiyoko Takeda

Shoji Kinomura

Yumi Momozono

An Ni-based alloy pipe for nuclear power has a chemical composition consisting of, in mass percent: C: 0.015 to 0.030%, Si: 0.10 to 0.50%, Mn: 0.10 to 0.50%, P: 0.040% or less, S: 0.015% or less, Cu: 0.01 to 0.20%, Ni: 50.0 to 65.0%, Cr: 19.0 to 35.0%, Mo: 0 to 0.40%, Co: 0.040% or less, Al: 0.30% or less, N: 0.010 to 0.080%, Ti: 0.020 to 0.180%, Zr: 0.010% or less, and Nb: 0.060% or less, the balance: Fe and impurities, and satisfying [(N&#x2212;Ti&#xd7;14/48)&#xd7;d&#x2265;4000] in relation to an average grain diameter, wherein a standard deviation of grain diameters is 20 &#x3bc;m or less, and a hardness of insides of grains is 180 HV or more.

Ni-based alloy pipe for nuclear power

A Ni-based alloy tube includes a base metal having a chemical composition consisting, by mass percent, of C: 0.15% or less, Si: 1.0% or less, Mn: 2.0% or less, P: 0.030% or less, S: 0.030% or less, Cr: 10.0 to 40.0%, Ni: 50.0 to 80.0%, Ti: 0.50% or less, Cu: 0.60% or less, Al: 0.20% or less, N: 0.20% or less, and the balance: Fe and impurities; and a low Cr content complex oxide film having a thickness of 25 nm or smaller at least on an inner surface of the base metal, wherein contents of Al, Ni, Si, Ti, and Cr in the film satisfy [at % Al/at % Cr&#x2264;2.00], [at % Ni/at % Cr&#x2264;1.40], and [(at % Si+at % Ti)/at % Cr&#x2265;0.10].

Ni-based alloy tube

A method for heat treating a metal tube or pipe is provided to perform heat treatment in such a manner that metal tubes or pipes () to be accommodated in a heat treatment furnace are laid down on a plurality of cross beams () arranged along a longitudinal direction of the metal tubes or pipes with the distance between adjacent cross beams being in a range of 200 to 2500 mm. This makes it possible to inhibit bending and scratches of the metal tubes or pipes without causing discoloration and deterioration of the manufacturing efficiency for the metal tubes or pipes. When the metal tubes or pipes () are laid down on the cross beams (), spacers may be interposed between the metal tubes or pipes () and the cross beams () on which they are laid down.

Method for heat treating a metal tube or pipe, metal tube or pipe, and heat treatment furnace

There is provided a Cr-containing austenitic alloy having a chromium oxide film with a thickness of 5 nm or larger on the surface, wherein the content of Mn in a base metal is, by mass percent, less than 0.1%. The chemical composition of the base metal desirably consists of, by mass percent, C: 0.15% or less, Si: 1.00% or less, Mn: less than 0.1%, P: 0.030% or less, S: 0.030% or less, Cr: 10.0 to 40.0%, Ni: 8.0 to 80.0%, Ti: 0.5% or less, Cu: 0.6% or less, Al: 0.5% or less, and N: 0.20% or less, the balance being Fe and impurities.

Cr-containing austenitic alloy and method for producing the same

There is provided a chromium-containing austenitic alloy wherein at least one surface of the surfaces of the alloy has a continuous chromium oxide film with a thickness of 5 nm or more and less than 50 nm. A maximum current density determined by a critical passivation current density method is 0.1 &#x3bc;A/cmor less when the chromium oxide film is continuous. A chemical composition of a base metal preferably consists of, by mass percent, C: 0.15% or less, Si: 1.00% or less, Mn: 2.0% or less, P: 0.030% or less, S: 0.030% or less, Cr: 10.0 to 40.0%, Ni: 8.0 to 80.0%, Ti: 0.5% or less, Cu: 0.6% or less, Al: 0.5% or less, and N: 0.20% or less, the balance being Fe and impurities.

Chromium-containing austenitic alloy

In performing cold rolling on a seamless pipe as a mother pipe, it is possible to inhibit the generation of metal chips from the end portions of the mother pipe, and to prevent the formation of indentations therein that may be caused by the metal chips to thereby provide good surface appearance. This is made possible by using a mother pipe () having end portions at the cold rolling starting side and finishing side that have been R-chamfered, at each outer edge and at each inner edge, such that (T&#x2212;T)/2&#x2266;R&#x2266;T/2 is satisfied, where R is a radius (mm) of the R-chamfer on the outer edges and the inner edges of the end portions, Tis a wall thickness of the mother pipe, and Tis a wall thickness of the pipe after cold rolling.

Method of cold rolling a seamless pipe

An austenitic heat resistant alloy, which contains, by mass percent, C&#x2266;0.15%, Si&#x2266;2%, Mn&#x2266;3%, Ni: 40 to 80%, Cr: 15 to 40%, W and Mo: 1 to 15% in total content, Ti&#x2266;3%, Al&#x2266;3%, N&#x2266;0.03%, O&#x2266;0.03%, with the balance being Fe and impurities, and among the impurities P&#x2266;0.04%, S&#x2266;0.03%, Sn&#x2266;0.1%, As&#x2266;0.01%, Zn&#x2266;0.01%, Pb&#x2266;0.01% and Sb&#x2266;0.01%, and satisfies the conditions [P1=S+{(P+Sn)/2}+{(As+Zn+Pb+Sb)/5}&#x2266;0.050], [0.2&#x2266;P2=Ti+2Al&#x2266;7.5&#x2212;10&#xd7;P1], [P2&#x2266;9.0&#x2212;100&#xd7;O] and [N&#x2266;0.002&#xd7;P2+0.019] can prevent both the liquation crack in the HAZ and the brittle crack in the HAZ and also can prevent defects due to welding fabricability, which occur during welding fabrication, and moreover has excellent creep strength at high temperatures. Therefore, the alloy can be used suitably as a material for constructing high temperature machines and equipment, such as power generating boilers, plants for the chemical industry and so on. The ally may contain a specific amount or amounts of one or more elements selected from Co, B, Ta, Hf, Nb, Zr, Ca, Mg, Y, La, Ce and Nd.

Austenitic heat resistant alloy

A high strength, ductile, and tough Ni-base heat resistant alloy comprises by mass percent, C: 0.1% or less, Si: 1% or less, Mn: 1% or less, Cr: not less than 15% to less than 28%, Fe: 15% or less, W: more than 5% to not more than 20%, Al: more than 0.5% to not more than 2%, Ti: more than 0.5% to not more than 2%, Nd: 0.001 to 0.1% and B: 0.0005 to 0.01%, with the balance being Ni and impurities. Impurity contents of P, S, Sn, Pb, Sb, Zn and As are P: 0.03% or less, S: 0.01% or less, Sn: 0.020% or less, Pb: 0.010% or less, Sb: 0.005% or less, Zn: 0.005% or less and As: 0.005% or less, and formulas of [0.015&#x2266;Nd+13.4&#xd7;B&#x2266;0.13], [Sn+Pb&#x2266;0.025] and [Sb+Zn +As&#x2266;0.010] are met.

Ni-base heat resistant alloy

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&#xb0; 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 &#x2212;60&#xb0; C. to +20&#xb0; C. After the front end of the Ni-base alloy tube reaches the outlet side of the furnace, the supply of atmospheric gas into the tube is switched to the supply from other gas supplying device. The operations are repeated.

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Tokyo, Japan

Osamu Miyahara