Mitsubishi Jukogyo Kabushiki Kaisha

Sumitomo Metal Industries, Inc.

Kichiro Onimura

Toshio Yonezawa

Hiroo Nagano

Kazuo Yamanaka

Hiroshi Susukida

Takao Minami

Nobuya Sasaguri

Yasutaka Okada

Mamoru Inoue

Katsuji Kawaguchi

Yaautaka Okada

Takaya Kusakabe

A nickel-chromium alloy excellent in a stress corrosion cracking resistance which is obtained by carrying out an annealing treatment under specific conditions, said alloy having the following composition:

Nickel-chromium alloy in stress corrosion cracking resistance

An alloy for heat transfer pipes excellent in an alkali stress corrosion cracking resistance which is obtained by heating and retaining said alloy at a temperature within the range of a temperature (T.degree.C.), at which a carbide in said alloy is thoroughly solubilized, to T+100.degree. C. for 1 minute or more; cooling it once to a level of 200.degree. C. or less; and carrying out a thermal treatment under conditions within a hatched range Z in FIG. 2, said alloy comprising: in terms of % by weight, 0.15% or less of C; 1.0% or less of Si; 1.0% or less of Mn; 25 to 35% of Cr; 40 to 70% of Ni; 0.5% or less of Al; 0.01 to 1.0% of Ti; 0.5 to 5.0%, in all, of one or more of Mo, W and V; 0.30% or less of P; 0.020% or less of S; and the residue of Fe and impurities.

Method for thermal treatment of alloy for heat transfer pipes

A method for a thermal treatment of a nickel based alloy, characterized in that said nickel based alloy for a material which will be subjected to a high-temperature and high-pressure water or vapor comprises, in terms of % by weight, 58% or more of Ni, 25 to 35% of Cr, 0.003% or less of B, 0.012 to 0.035% of C, 1% or less of Mn, 0.5% or less of Si, 0.015% or less of P, 0.015% or less of S, and the residue of Fe and usual impurities; in a first thermal treatment process, said nickel based alloy is heated and retained at a temperature of T.degree. C. to (T+100).degree.C. and is cooled at a cooling rate of a furnace cooling rate or more; and in a second thermal treatment process, said nickel based alloy is then retained at a temperature of 600.degree. to 750.degree. C. and at a temperature within a sensitization recovery range for a period of 0.1 to 100 hours and is cooled at a cooling rate of said furnace cooling rate or more.

Method for thermal treatment of nickel based alloy materials

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Takasago, Japan

Kichiro Onimura