| 摘要 |
PROBLEM TO BE SOLVED: To provide a steel sheet having a large sheet thickness and excellent in high temperature strength and toughness in a sheet thickness center part after PWHT and a manufacturing method therefor.SOLUTION: There is provided a manufacturing method for a steel sheet excellent in high temperature strength and toughness, having a steel composition containing predetermined components and the balance Fe with an inevitable impurities, X represented by the following formula (A) of 22.6 or more, an inverse number of square root of effective crystal grain diameter of 8.5 mmor more and tensile strength at 454°C of the steel sheet after stress relief annealing of 470 MPa or more and Charpy impact absorption energy at -40°C of 150 J or more. X=4Cr+11Mo+10 V (A), where Cr:mass% of Cr, Mo:mass% of Mo and V:mass% of V.SELECTED DRAWING: Figure 2 |
