| 摘要 |
Disclosed is a high strength steel pipe which contains, in mass%, 0.02-0.09% of C, 0.4-2.5% of Mn, 0.1-1.0% of Cr, 0.005-0.03% of Ti, and 0.005-0.3% of Nb, with the balance made up of iron and unavoidable impurities, while limiting Si to 0.6% or less, Al to 0.1% or less, P to 0.02% or less, S to 0.005% or less, and N to 0.008% or less. The high strength steel pipe has a bainite transformation index (BT) of 650°C or less, and has a metallic structure that is composed of a simple bainite structure containing a first bainite and a second bainite. The first bainite is a texture of a bainitic ferrite containing no carbide, and the second bainite is a mixture of the bainitic ferrite containing no carbide and cementite in the bainitic ferrite.
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