Method of making quenched and tempered steel pipe with high fatigue life
AssigneeNisshin Steel Co., Ltd.
InventorsMasaru Fujihara, Tsunetoshi Suzaki
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Abstract
A method for producing a high fatigue life quenched/tempered steel pipe comprises a quenching treatment of keeping an unquenched starting steel pipe having a composition that comprises, % by mass, C: 0.1 to 0.4%, Si: 0.5 to 1.5%, Mn: 0.3 to 2%, P: at most 0.02%, S: at most 0.01%, Cr: 0.1 to 2%, Ti: 0.01 to 0.1%, Nb: 0.01 to 0.1%, Al: at most 0.1%, B: 0.0005 to 0.01%, and N: at most 0.01%, with a balance of Fe and inevitable impurities, at 900 to 1100° C. for 10 to 60 seconds and then rapidly cooling it. The cooled pipe is subjected to a tempering treatment of keeping the pipe at 280 to 380° C. for 10 to 60 minutes.
Claims3
A method for producing a high fatigue life quenched/tempered steel pipe, comprising quenching treatment:
- of keeping an unquenched starting steel pipe having a composition that comprises, % by mass, C:
- 0.1 to 0.4%, Si:
- 0.65 to 1.5%, Mn:
- 0.3 to 2%, P:
- at most 0.02% S:
- at most 0.01%, Cr:
- 0.1 to 2%, Ti:
- 0.01 to 0.1%, Nb:
- 0.01 to 0.1%, Al:
- at most 0.1% B:
- 0.0005 to 0.01%, and N:
- at most 0.01%, with a balance of Fe and inevitable impurities, at 900 to 1100° C. for 10 to 60 seconds and then cooling the pipe such that the pipe undergoes martensitic transformation, followed by tempering treatment of keeping it at 280 to 380° C. for 10 to 60 minutes.
Dependencies are inferred from the claim text.