Abstract: The invention relates to a 9Ni steel plate for ship LNG storage tank with high strength and low yield ratio. According to the mass percentage, the chemical constituents are C: 0.02-0.05%, Si: 0.10-0.30%, Mn: 0.50-0.80%, Ni: 8.90-9.50%, P: ?0.0070%, s: ?0.0020%, Cr: 0.10-0.25%, Alt: 0.010-0.035%, Nb: 0.010-0.020%, Ca: 0.0005-0.0030%, O: ?0.0012%, N: ?0.004%, H: ?0.00015%, and the balance is Fe and unavoidable impurity elements. The production process flow is: smelting in a converter or electric furnace->RH vacuum degassing->LF refining->RH high vacuum degassing->Ca Treatment->continuous casting->slab slow cooling treatment->slab surface cleaning->heating->rolling ->quenching->tempering. For the 9Ni steel, especially the 9Ni thin steel plate, the invention adopts the constituents design of low C, 9% Ni, addition of Nb and Cr.

Abstract: The invention relates to a wear-resistant steel with excellent surface quality, which is composed of C: 0.12-0.20%, Si: ?0.1%, Mn: 0.6-1.20%, Nb: 0.010-0.040%, V: ?0.01%, Ti: 0.010%-0.030, Al: ?0.04%, Ni: ?0.1%, Cu: ?0.1%, Cr: 0.10-0.40%, Mo: ?0.1%, B: 0.001-0.005%, Ca: 0.0010-0.0050%, P: ?0.010%, S: ?0.0015%, O: ?0.0012%, N: ?0.0035%, H: ?0.0002%, the balance is Fe, and the carbon equivalent CEV?0.4; PCM?0.25. The production process flow is: converter smelting->LF refining->VD or Rh high vacuum degassing->continuous casting->heating->rolling->shot blasting->quenching->tempering. The wear-resistant steel of the invention has better surface quality, and there are no surface defects such as air pit, inclusion, hemp pit and pressed iron oxide scale. The depth of surface spots caused by the peeling off iron oxide scale is ?0.1 mm, and the surface grinding of steel plate cannot be carried out. Based on element design, non-preheating welding and excellent toughness can be further realized.

Abstract: The present invention relates to a rack steel plate with a thickness up to 177.8 mm by a continuous casting slab, the constituents and mass percentages including C0.11˜0.15%, Si0.15˜0.35%, Mn0.95˜1.25%, P?0.010%, S?0.002%, Cr0.45˜0.75%, Mo0.4˜0.6%, Ni1.3˜2.6%, Cu0.2˜0.4%, Al0.06˜0.09%, V0.03˜0.06%, Nb?0.04%, N?0.006%, B0.001˜0.002%, the balance is Fe and unavoidable impurity elements. The manufacture method includes, in sequence, KR molten steel pretreatment, converter smelting, LF refining, RH refining, continuous casting through a straight-arc continuous casting machine, shielding the continuous casting slab a cover and slowly cooling, cleaning the continuous casting slab, heating, high-pressure water descaling, control rolling, straightening, slowly cooling, quenching and tempering treatment.

Abstract: An ultra-heavy steel plate with low cracking sensitivity and low yield ratio, the mass percentages of chemical components of the steel plate are C 0.05-0.09; Si 0.2-0.4; Mn 1.3-1.6; Al 0.02-0.04; Nb 0.03-0.08; V 0.03-0.08; Cr 0.1-0.5; Ni 0.1-0.5; Mo 0.1-0.3; Cu 0.2-0.5; Ti 0.01-0.02; P?0.015; S?0.003; N?0.007, the balance being Fe and inevitable impurities; the carbon equivalent is ?0.43, the cold cracking sensitivity coefficient Pcm is ?0.20. A low cracking sensitivity and low yield ratio steel plate with a thickness of 40-70 mm is manufactured by the process steps of KR molten iron pretreatment-converter smelting-LF refining-RH vacuum degassing-continuous casting-lid-covering slow cooling for the continuous casting slabs-casting slabs heating-controlled rolling-controlled cooling-hot straightening-air cooling and so on.

Abstract: The present invention relates to a rack steel plate with a thickness up to 177.8 mm by a continuous casting slab, the constituents and mass percentages including C0.11˜0.15%, Si0.15˜0.35%, Mn0.95˜1.25%, P?0.010%, S?0.002%, Cr0.45˜0.75%, Mo0.4˜0.6%, Ni1.3˜2.6%, Cu0.2˜0.4%, Al0.06˜0.09%, V0.03˜0.06%, Nb?0.04%, N?0.006%, B0.001˜01002%, the balance is Fe and unavoidable impurity elements. The manufacture method includes, in sequence, KR molten steel pretreatment, converter smelting, LF refining, RH refining, continuous casting through a straight-arc continuous casting machine, shielding the continuous casting slab a cover and slowly cooling, cleaning the continuous casting slab, heating, high-pressure water descaling, control rolling, straightening, slowly cooling, quenching and tempering treatment.

Abstract: An ultra-heavy steel plate with low cracking sensitivity and low yield ratio, the mass percentages of chemical components of the steel plate are C 0.05-0.09; Si 0.2-0.4; Mn 1.3-1.6; Al 0.02-0.04; Nb 0.03-0.08; V 0.03-0.08; Cr 0.1-0.5; Ni 0.1-0.5; Mo 0.1-0.3; Cu 0.2-0.5; Ti 0.01-0.02; P?0.015; S?0.003; N?0.007, the balance being Fe and inevitable impurities; the carbon equivalent is ?0.43, the cold cracking sensitivity coefficient Pcm is ?0.20. A low cracking sensitivity and low yield ratio steel plate with a thickness of 40-70 mm is manufactured by the process steps of KR molten iron pretreatment-converter smelting-LF refining-RH vacuum degassing-continuous casting-lid-covering slow cooling for the continuous casting slabs-casting slabs heating-controlled rolling-controlled cooling-hot straightening-air cooling and so on.