| 摘要 |
PURPOSE: A method for producing a thick steel plate is provided to prevent transmitting speed of fatigue crack from accelerating even in oil containing much H2S gas. CONSTITUTION: A steel slab is composed of more than one among 0.03 to 0.20wt% of C, 0.05 to 0,5wt% of Si, 0.5 to 2.0wt% of Mn, less than 0.03wt% of P, less than 0.01wt% of S, 0.001 to 0.1wt% of Al, 0.005 to 0.020wt% of Ti, 0.1 to 0.35wt% of Cr, 0.1 to 0.35wt% of W and 0.1 to 0.35wt% of Cu, and also contains the remain of Fe and impurities. The steel slab is reheated in a temperature of 1100 to 1250°C and rough rolled. The slab is rolled for final controlling in a temperature of more than 800°C. The slab is not rolled in a temperature section of 900 to 1000°C and cooled with water at 3°C/second to 10°C/second of speed. In a temperature section of 500 to 800°C, the slab is cooled at 5 to 15°C/second of speed.
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