Martensitic stainless steel pipe and method of manufacturing the same
AssigneeNippon Steel Corporation
InventorsMikiko Noguchi, Takashi Yamaguchi
Life of this patent
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Abstract
A method of manufacturing a martensitic stainless steel pipe includes: preparing a hollow shell, S1; a pickling step, S3-2, in which the hollow shell is immersed in nitrohydrofluoric acid solution at a temperature below 50° C.; after pickling step S3-2, a high-pressure water washing step, S4, in which high-pressure water is injected onto the outer surface of the hollow shell to clean the outer surface of the hollow shell; after high-pressure water washing step S4, a hot-water immersion step, S5, in which the hollow shell is immersed in hot water if necessary; and spraying gas onto the surface of the hollow shell, S6, before a lapse of 15 minutes from completion of high-pressure water washing step S4 or hot-water immersion step S5.
Claims4
A method of manufacturing a martensitic stainless steel pipe, comprising:
- preparing a hollow shell having a chemical composition of, in mass %:
- 0.001 to 0.050% C;
- 0.05 to 1.00% Si;
- 0.05 to 1.00% Mn;
- up to 0.030% P;
- up to 0.0020% S;
- below 0.50% Cu;
- 11.50 to below 14.00% Cr;
- above 5.00 to 7.00% Ni;
- above 1.00 to 3.00% Mo;
- 0.02 to 0.50% Ti;
- 0.001 to 0.100% Al;
- 0.0001 to 0.0040% Ca;
- 0.0001 to below 0.0200% N;
- 0 to 0.500% V;
- 0 to 0.500% Nb;
- 0 to 0.500% Co;
- and
- balance Fe and impurities;
- a pickling step in which the hollow shell is immersed in nitrohydrofluoric acid solution at a temperature below 50° C.;
- after the pickling step, a high-pressure water washing step in which high-pressure water is injected onto an outer surface of the hollow shell to clean the outer surface of the hollow shell and a discharge pressure of an injection nozzle of a high-pressure water washer is not lower than 0.98 MPa;
- and
- a gas spraying step in which the outer surface of the hollow shell is sprayed with gas before a lapse of 15 minutes from completion of the high-pressure water washing step.
A method of manufacturing a martensitic stainless steel pipe comprising:
- preparing a hollow shell having a chemical composition of, in mass %:
- 0.001 to 0.050% C;
- 0.05 to 1.00% Si;
- 0.05 to 1.00% Mn;
- up to 0.030% P;
- up to 0.0020% S;
- below 0.50% Cu;
- 11.50 to below 14.00% Cr;
- above 5.00 to 7.00% Ni;
- above 1.00 to 3.00% Mo;
- 0.02 to 0.50% Ti;
- 0.001 to 0.100% Al;
- 0.0001 to 0.0040% Ca;
- 0.0001 to below 0.0200% N;
- 0 to 0.500% V;
- 0 to 0.500% Nb;
- 0 to 0.500% Co;
- and
- balance Fe and impurities;
- a pickling step in which the hollow shell is immersed in nitrohydrofluoric acid solution at a temperature below 50° C.;
- after the pickling step, a high-pressure water washing step in which high-pressure water is injected onto an outer surface of the hollow shell to clean the outer surface of the hollow shell and a discharge pressure of an injection nozzle of a high-pressure water washer is not lower than 0.98 MPa;
- after the high-pressure water washing step, a hot-water immersion step in which the hollow shell is immersed in hot water;
- and
- a gas spraying step in which the outer surface of the hollow shell is sprayed with gas before a lapse of 15 minutes from completion of the hot-water immersion step.
Dependencies are inferred from the claim text.