Ni base alloy pipe stock and method for manufacturing the same

Abstract

A Ni base alloy pipe stock having a chemical composition comprising, by mass %, C≦0.04%, Si≦0.50%, Mn: 0.01 to 6.0%, P≦0.03%, S≦0.01%, Cr: 15 to 30%, Ni: more than 45% to not more than 60%, Mo: 0 to 18%, W: 0 to 36%, with Mo(%)+0.5W(%): more than 1.5% to not more than 18%, Cu: 0.01 to 1.5%, Al≦0.01% and N: 0.0005 to 0.20%, and the balance substantially being Fe, with 1380−5000P−100S−4400C≧1300, Ni+10(Mo+0.5W)+100N≦200, (Ni−50)+10(N−0.1)−2(Cr−25)−5(Mo+0.5W−6)+12≧0, can be manufactured into a seamless pipe by use of a Mannesmann piercing and rolling mill because of its excellent inner surface properties. The resulting seamless pipe has excellent mechanical properties and moreover has excellent corrosion resistance in a sour gas environment, and thus, the Ni base alloy pipe stock can be used as a pipe stock for oil country tubular goods and line pipes and further as a pipe stock for various structural members of nuclear power plants and chemical industrial plants.

Dependencies are inferred from the claim text.