| 摘要 |
A method of making an UOE steel pipe having excellent deformability and low-temperature toughness includes providing a steel composition with a controlled composition consisting essentially of C: 0.03-0.07%, Si: 0.05-0.50%, Mn: 1.6-2.2%, P: at most 0.020%, S: at most 0.003%, Cu: 0.20-0.60%, Cr: at most 0.10%, Ni: 0.20-0.80%, Nb: 0.005-0.030%, Ti: 0.005-0.030%, N: at most 0.0070%, Al: 0.005-0.060%, and a remainder of Fe and impurities, a hardenability index Pcm of at most 0.22%, Cu+Cr+Ni is 0.4-1.5%, and Nb+Mo+V is at most 0.05%. The pipe has a yield strength in the longitudinal direction of at least 480 MPa, a yield-tensile ratio of at most 85% and a Charpy absorbed energy of the heat affected zone at−40° C. of at least 40 J.
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