| 摘要 |
PURPOSE:To obtain a hot coil for line pipe improved for hydrogen induced crack resistance, by a method wherein very low S low alloy steel continuous casting slab of a specific composition is kept heated under specific conditions, break- down-rolled, heated and continuously hot-rolled. CONSTITUTION:The slab consisting of 0.15wt% max, C, 0.05-0.50% Si, 0.50- 1.50% Mn, 0.020% max. P, 0.003% max. S, 0.070% max. Al1 0.10-0.50% Cu, 0.10-0.50% Ni, 0.0010-0.0060% Ca, remainder Fe and inevitable impurities is continuously casted. After keeping this continuous casting slab at 1,250 deg.C min. for 5hr min., it is break-down-rolled by 20wt% min. in break-down ratio. Then, after keeping it at 1,150 deg.C min. for 3hr min., it is continuously hot-rolled and the coil in manufactured. By this method, the line pipe coil for soun gas having no hydrogen induced crack can be obtained. |
