80MM-THICK LOW-COST FH420 MARINE STEEL PLATE AND MANUFACTURING METHOD THEREFOR

摘要

An 80mm-thick low-cost FH420 marine steel plate, components thereof being, in weight percentage: C: 0.07-0.11%, Si: 0.15-0.40%, Mn: 1.30-1.60%，P ≤ 0.013%, S ≤ 0.003%, Nb: 0.010-0.030%, V: 0.030-0.050%, Ti: 0.005-0.020%, Cr: 0.10-0.20%, Al: 0.0250-0.050%, O ≤ 18ppm, N ≤ 38ppm, H ≤ 2.5ppm, and the remainder being Fe and unavoidable impurities. The manufacture of present marine steel plate uses thermomechanical controlled processing. The heating temperature before rolling is 1150°C-1220°C, the rough rolling temperature is 980-1080°C, and the finish rolling starting temperature is 840-870°C. After rolling, laminar cooling is performed, the final cooling temperature being 600-660°C, and the cooling rate being 5-8°C/s. Quenching treatment is performed at a temperature of 890-910°C, the heating rate being 1.4min/mm and the holding time being 0-25min, and tempering treatment is performed at a temperature of 550-650°C, the heating rate being 2.0min/mm, and the holding time being 80-120min.