Large-specification and high-strength D40 hot-rolled flat-bulb steel for ships and production process for hot-rolled flat-bulb steel

Abstract

The invention relates to large-specification and high-strength D40 hot-rolled flat-bulb steel for ships and a production process for the hot-rolled flat-bulb steel, and belongs to the technical field of marine structural steel. The large specification of the large-specification and high-strength hot-rolled flat-bulb steel is No. 40 and over No.40. The steel comprises the following chemical ingredients in percentage by weight: 0.08 to 0.15 percent of C, 0.10 to 0.50 percent of Si, 1.15 to 1.75 percent of Mn, less than or equal to 0.020 percent of S, less than or equal to 0.020 percent of P, 0.08 to 0.15 percent of V, 0.10 to 0.50 percent of Ni, 0.01 to 0.03 percent of Ti, 0.001 to 0.01 percent of Mg, 0.001 to 0.01 percent of Ca, 0.001 to 0.01 percent of O, 0.016 to 0.025 percent of N and the balance of Fe and inevitable impurities, wherein Mn / C is more than or equal to 14.0, Ni / Mn is more than or equal to 0.15, and (Mg+Ca) / O is more than or equal to 1.0. The production process comprises the following steps of: feeding a vanadium nitrogen alloy wire with the diameter of 13 millimeters and a Mg-Ca alloy wire with the diameter of 10 millimeters into molten steel after vacuum is finished, and blowing argon and stirring at the bottom; and in the hot rolling process, heating a low-temperature blank, performing final rolling for large deformation and cooling after rolling. The large-specification and high-strength D40 hot-rolled flat-bulb steel has the advantages that: the requirements of yield strength and impact toughness at the low temperature of -40 DEG C can be met, the flat-bulb steel is used for stiffeners at bilge keels of large-scale ships, and the rigidity of the ships and the safety coefficients of the ships used at the low temperature are improved obviously under the condition that the weight of the ships is not improved.

Description

technical field [0001] The invention belongs to the technical field of marine structural steel, and in particular relates to a large-scale high-strength D40 marine hot-rolled flat bulb steel and a production process thereof. The large-scale refers to No. 40 and above. Background technique [0002] Bulb flat steel is an auxiliary profile mainly used in the construction of various large and medium-sized ships, and its consumption is second only to marine steel plates. Studies have shown that when the section modulus is the same or similar, the penetration moment of the bulbous flat steel is generally larger than that of the unequal angle steel, the equilateral angle steel, the flat steel and the T section, and the cross-sectional area is smaller, so it becomes the main improvement. The moment of penetration of the hull, ensuring the rigidity of the hull and reducing the weight of the hull are indispensable components. With the development of large-scale, high-speed and automa...

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Problems solved by technology

[0008] The object of the present invention is to provide a 40# and above large-scale high-strength D40 marine flat bulb and its production process, which is used to solve the high yield strength and -40℃ low-temperature impact energy of 40# and above large-scale marine bulb Problem: It can meet the requirements of high yield strength and low temperature impact energy at -40°C for hull structures of 100,000 tons and above for large-scale flat bulb steels of No. 40 and above

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