Nippon Steel Sumitomo Metal Corporation

Sumitomo Metal Industries, Inc.

Nippon Steel Corporation

Shoji Kinomura

Manabu Kanzaki

Yasuhiro Masaki

Masanari Kimoto

Osamu Miyahara

Mitsuharu Yonemura

Yoshiyuki Nakao

Kiyoko Takeda

Masahito Tasaka

Hiroyuki Anada

Toshihiro Imoto

Kazuyuki Kitamura

Akihiro Uehira

Yumi Momozono

Shinichi Takenaka

Toshiya Kodai

Shugo Nishiyama

An object of the present invention is to provide an Ni-based alloy pipe or tube for nuclear power with reduced rate of SCC crack propagation. The Ni-based alloy pipe or tube for nuclear power according to the present invention is an Ni-based alloy pipe or tube having a wall thickness of 15 to 55 mm, having a chemical composition of, in mass %: 0.010 to 0.025% C; 0.10 to 0.50% Si; 0.01 to 0.50% Mn; up to 0.030% P; up to 0.002% S; 52.5 to 65.0% Ni; 20.0 to 35.0% Cr; 0.03 to 0.30% Mo; up to 0.018% Co; up to 0.015% Sn; 0.005 to 0.050% N; 0 to 0.300% Ti; 0 to 0.200% Nb; 0 to 0.300% Ta; 0% or more and less than 0.03% Zr; and the balance being Fe and impurities, wherein the Ni-based alloy pipe or tube has a microstructure being an austenite single phase, and the chemical composition satisfies the following equation, Eq. (1):&#x2212;0.0020&#x2264;[N]/14&#x2212;{[Ti]/47.9+[Nb]/92.9+[Ta]/180.9+[Zr]/91.2}&#x2264;0.0015&#x2003;&#x2003;Eq. (1).For the element symbols in Eq. (1), the contents of the corresponding elements in mass % are substituted.

Ni-based alloy pipe or tube 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

There is provided a Cr-containing austenitic alloy tube, wherein a chromium oxide film with a thickness of 0.05 to 1.5 &#x3bc;m having the relationship defined by Formula (i) is formed on the inner surface of the tube, wherein the average concentration of C in the depth range of 5 to 10 &#x3bc;m from the inner surface is lower than the concentration of C in a base metal;0.4&#x2266;&#x3b4;1/&#x3b4;2&#x2266;2.5&#x2003;&#x2003;(i)wherein &#x3b4;1 and &#x3b4;2 are thicknesses (&#x3bc;m) of the chromium oxide film at both ends of tube, respectively.

Cr-containing austenitic alloy tube and method for producing the same

In a method for heat treating a metal tube or pipe for a nuclear power plant, the tube or pipe being accommodated in a batch-type vacuum heat treatment furnace, when the tube or pipe is laid down on and is subjected to heat treatment on a plurality of metal cross beams arranged along a longitudinal direction of the tube or pipe, it is possible to suppress scratches to be formed on the outer surface of the tube or pipe and attributable to heat treatment, and to reduce the discoloration on the outer surface of the tube or pipe by holding the tube or pipe and the metal cross beams in indirect contact with each other by virtue of a heat resistant fabric having a thickness of 0.1 to 1.2 mm interposed in between.

Method for heat-treating metal tubes or pipes for nuclear power plant

A Ni&#x2014;Cr alloy tube demonstrating an excellent corrosion resistance in a high temperature water environment can be provided,

Ni-Cr alloy material

A method in accordance with the present invention includes the steps of: separating an eddy current signal into an X-axis component and a Y-axis component to obtain signal waveform data of the respective components; excluding predetermined low-frequency components respectively from the respective signal waveform data thus obtained; calculating a noise voltage value Vdefined by the following Equation (1) based upon voltage values X(i) and Y(i) of the signal waveform data of the X-axis component and the Y-axis component from which the low-frequency components have been excluded; and calculating an S/N ratio by dividing a voltage value D of an eddy current signal corresponding to a predetermined artificial flaw by the noise voltage value V: where n represents the number of samplings of the signal waveform data.

S/N ratio measuring method in eddy current testing on internal surface of pipe or tube

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Takarazuka, Japan

Shoji Kinomura