| 摘要 |
PURPOSE: A process for preparing steel for oil well use by suitably controlling the amount of Si, Al, Ca and Mn exerting an influence on graphitization of carbon steel and annealing conditions is provided. Whereby, the obtained steel has improved hydrogen-induced cracking resistance. CONSTITUTION: A hot rolled steel sheet comprising by weight, C:0.3 to 0.6%, Si:0.1 to 1.5%, Mn:0.1 to 0.5%, Al:0.01 to 0.1%, P:0.03% or less, S:0.01% or less and the balance of Fe and other inevitable impurities is prepared and annealed at 650 to 710deg.C to produce steel for oil well use improved in hydrogen-induced cracking resistance.
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