390 MPa class low-temperature hull steel having excellent toughness and manufacturing method thereof

Abstract

The invention discloses 390 MPa class low-temperature hull steel having excellent toughness and a manufacturing method thereof. The hull steel comprises, by weight, 0.05-0.12% of carbon, 0.08-0.30% of silicon, 1.0-1.40% of manganese, not more than 0.01% of phosphorus, not more than 0.01% of sulphur, 0.01-0.05% of aluminum, 0.02-0.04% of niobium, 0.005-0.020% of titanium with the balance being ferrum and unavoidable impurities. A first stage rolling temperature is 1050-1100 DEG C, a total reduction rate is not less than 60% and a finish rolling temperature is 900-940 DEG C; a second stage rolling temperature is 850-900 DEG C, the total reduction rate is not less than 60% and the finish rolling temperature is 790-880 DEG C. The steel is the steel is subjected to ultra-rapid cooling at a cooling speed of larger than 30 DEG C per second and is cooled at a cooling speed of larger than 10 DEG C per second in a manner of laminar flow; a self-tempering temperature of the steel ranges from 580-640 DEG C and the final cooling temperature of the steel ranges from 500-630 DEG C; and the steel is air cooled to the room temperature.

Description

technical field [0001] The invention belongs to the field of steel material preparation, and in particular relates to a 390MPa low-temperature marine steel with excellent toughness and a TMCP manufacturing method based on an ultrafast cooling (UFC) process. Background technique [0002] The Arctic has harsh living conditions, but it is rich in oil and gas resources, fishery resources and various minerals; the Antarctic has rich fishery resources. With the increasing shortage of global energy and natural resources and rising international energy prices, more and more countries are turning their attention to these low-temperature sea areas. Therefore, the demand and requirements for marine steel in low-temperature sea areas are increasing day by day. Ship plate steel with high strength, especially low temperature and high toughness is an urgent demand in the market. However, the manufacture of high strength, low temperature and high toughness ship plate steel according to conv...

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Problems solved by technology

[0006] The manufacturing method proposed in the invention patent "method of producing steel having high strength and toughness" with the publication number CA1182721A, its chemical composition contains Ni, Mo, Cu alloy elements, which increases the manufacturing cost; at the same time, the final rolling temperature is required to be less than 750°C, which It will inevitably increase the rolling waiting time and affect the rolling efficiency

[0007] The invention patent with the publication number CN101705434A proposes a ship plate steel with ultra-high strength and impact toughness and its preparation method. Its chemical composition contains Mo, Cu, Ni, Cr alloy elements, which increases the cost of the alloy; The steel plate is heat treated, which increases the manufacturing cost

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