| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for producing an ultra-high strength steel plate and steel pipe having excellent low temperature toughness and≥900 MPa tensile strength by which fine-granulation of crystal grain is performed by further promoting recrystallization inγ-recrystallization zone rolling and the low temperature toughness having≥200 J shelf-energy (Charpy energy) is obtained. SOLUTION: In the method for producing the ultra-high strength steel plate having≥900 MPa tensile strength and excellent low temperature toughness, after reheating a continuously cast slab containing a prescribed component and consisting essentially of bainite and martensite in the casting structure, a hot-rolling at≥900°C rolling temperature in the recrystallization zone,≥5% average rolling-reduction ratio per one pass of each rolling and≥3 sec passing time of each rolling, is performed. COPYRIGHT: (C)2004,JPO |
