| 摘要 |
A manufacturing method of high corrosionresistant low-alloy steel for line pipes improved in CO2 corrosion resistance without deteriorating low-temperature toughness of base material and weld heat-affected zone and field weldability. The invention steel comprises, by weight %, 0.02 to 0.09 carbon, 0.5 or less silicon, 0.7 to 1.5 manganese, 0.03 or less phosphorus, 0.005 or less sulfur, 0.02 to 0.06 niobium, 0.5 to not more than 1.2 chromium, 0.005 to 0.03 titanium, 0.05 or less aluminum, 0.002 to 0.005 nitrogen, and the balance of iron and unavoidable impurities, and satisfies the following equation: 0.35 ? C + (Mn + Cr + V)/5 + (Ni + Cu)/15 ? 0.48. The steel is heated at a temperature in a range of 1100.degree.C to 1250.degree.C, rolled with the cumulative rolling reduction at 950.degree.C or less being 40% or more, a finish rolling temperature of 700.degree.C to 850.degree.C, and then, air-cooled or acceleratedly cooled.
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