| 摘要 |
PROBLEM TO BE SOLVED: To provide a method of manufacturing a high strength hot rolled steel plate minimal in dispersion of strength and elongation and excellent in stability of material quality and weldability. SOLUTION: The method for manufacturing the high strength hot rolled steel plate includes steps of: manufacturing a slab having a composition containing, by mass, 0.05-0.09% C, 0<=.05% Si, 0.4-2% Mn, <=50.02% P, <=0.005% S, 0.01-0.1% sol.Al, 0.001-0.008% N and 0.03-0.15% Ti; hot rolling the slab at finishing temperature between the Ar3 point and 860 deg.C; and cooling the resultant hot rolled steel plate to 630 deg.C at average cooling rate CR( deg.C/s) satisfying inequality 143×[Ti]+3<=CR<=143×[Ti]+23 (1),M/). Further, one or more kinds among <=1% Cr, <=1% Mo, <=0.1% Nb and <=0.1% V can be incorporated into the above composition.
|
