Sumitomo Metal Industries, Inc.

Masamichi Kowaka

Hisao Fujikawa

Herein disclosed is a low carbon austenitic steel having an improved resistance to stress corrosion cracking. The austenitic steel consists essentially of, by weight; less than 0.029% of carbon; 1.5 to 4.0% of silicon; 0.1 to 3.0% of manganese; 23 to 45% of nickel; 20 to 35% of chromium; 0.5 to 4.0% of vanadium; titanium in an amount of at least 5 times carbon content and up to 1% of the total composition, and/or niobium in an amount of at least 7 times carbon content and up to 1% of the total composition, and/or zirconium in an amount of at least 7 times carbon content and up to 1% of the total composition, and/or tantalum in an amount of at least 7 times carbon content and up to 2% of the total composition, and/or tungsten in an amount of at least 5 times carbon content and up to 2% of the total composition, the total amount of titanium and/or niobium and/or zirconium and/or tantalum and/or tungsten being in the range of at least 5 times carbon content and up to 2% of the total composition; if desired, copper and/or molybdenum in a total amount of 0.3 to 4%; and the balance of iron. This steel has outstanding utility as the materials of heat exchangers or pipes for generation of steam in nuclear reactors.

Low carbon Ni-Cr austenitic steel having an improved resistance to

Herein disclosed is an Ni-Cr-Fe alloy being substantially in the single phase of austenite and improved in resistance to stress corrosion cracking. The alloy contains, by weight; 0.03 to 0.12% of carbon; 0.2 to 4% of silicon; 0.1 to 3% of manganese; 12 to 45% of nickel; 15 to 35% of chromium; vanadium and/or aluminum, the total amount of vanadium and aluminum being in the range of 0.2 to 4.0%, titanium in an amount of at least 5 times the carbon content and up to 1% of the total composition, and/or niobium in an amount of at least 7 times the carbon content and up to 1% of the total composition, and/or zirconium in an amount of at least 7 times the carbon content and up to 1% of the total composition, and/or tungusten in an amount of at least 5 times the carbon content and up to 2% of the total composition, the total amount of titanium and/or niobium and/or zirconium and/or tungusten being in the range of 0.3 to 2%; if desired, copper and/ or molybdenum in a total amount of 0.3 to 4%; and the balance of iron. This alloy has outstanding utility as structural material of heat exchanger, such as U-shaped tube of the nuclear reactor.

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Toyanaka, Japan

Masamichi Kowaka