High strength Cr-Ni alloy seamless tube manufacturing method

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A method for producing a high-strength Cr-Ni alloy seamless pipe, excellent in hot workability and stress corrosion cracking resistance, without causing the lamination during piercing-rolling, comprising : preparing an alloy billet that has a chemical composition comprising, by mass%, of C : 0.05% or less, Si : 1.0% or less, Mn : less than 3.0%, P : 0.005% or less, S : 0.005% or less, Cu : 0.01 to 4.0%, Ni : 25% or more and less than 35%, Cr : 20 to 30%, Mo : 0.01% or more and less than 4.0%, N : 0.10 to 0.30%, Al : 0.03 to 0.30%, O (oxygen) : 0.01% or less, REM (rare earth metal) : 0.01 to 0.20%, and the balance being Fe and impurities, and satisfying the following formula (1); hot working to make a seamless material pipe on the basis of a cross roll piercing process; subjecting a solution treatment; and cold working. N × P / REM ‰¤ 0.10 wherein P, N and REM in formula (1) represent the contents (mass%) of P, N and REM, respectively. The Cr-Ni alloy may further contain one or more of W, Ti, Nb, Zr, V, Ca and Mg.