Carbon manganese low-temperature steel for liquefied gas boat and manufacturing method of carbon manganese low-temperature steel

Abstract

The invention discloses carbon manganese low-temperature steel for a liquefied gas boat and a manufacturing method of the carbon manganese low-temperature steel. The carbon manganese low-temperature steel comprises, by weight, 0.03%-0.08% of C, 0.10%-0.30% of Si, 0.60%-1.30% of Mn, not larger than 0.015% of P, not larger than 0.005% of S, 0.010%-0.080% of Nb, 0.010%-0.060% of Al and the balance Fe and inevitable impurities. The clean steel smelting-continuous casting process is adopted in the method, and a high-purity homogenous continuous casting slab is manufactured; and through two-stage control rolling and control cooling, a wee ferrite and pearlitic structure is obtained. The carbon manganese low-temperature steel for the liquefied gas boat has the beneficial effects that the steel is pure, the texture is even, the grain size is in the 10.0 level to 13.5 level, and the ductile-brittle transition temperature is lower than -80 DEG C; building requirements of a cargo tank and a boat body structure of the liquefied gas boat are met; and meanwhile, the carbon manganese low-temperature steel has the beneficial effects of being simple in chemical component and low in cost.

Description

technical field [0001] The invention belongs to the field of alloy steel manufacturing, and relates to a carbon-manganese low-temperature steel for liquefied gas ships and a manufacturing method thereof. Background technique [0002] Liquefied petroleum gas (LPG for short) is widely used for its convenient use, cleanliness and less pollution. With the continuous rapid development of my country's economy, the gradual improvement of people's living standards, the rapid growth of urban population and the enhancement of environmental protection awareness, the demand for LPG has grown rapidly, and it has become the third largest liquefied gas consumption market in the world. As the domestic production lags far behind the demand, the import volume has greatly increased, and accordingly, the LPG shipping market has also developed accordingly. LPG ships mainly transport petroleum hydrocarbons with propane and butane as the main components or a mixture of the two, including propylen...

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Problems solved by technology

[0004] Such as "a low-temperature steel plate for pressure vessel" (application publication number: CN104674110), the mass percentage of the chemical composition of the steel plate is: C0.03-0.07%, Si0.15-0.3%, Ni6.8-8.0%, Mn0.6-0.9%, P≤0.005%, S≤0.005%, Al0.02-0.04%, Mo0.01-0.2%, Nb0.01-0.09%, the balance is Fe and unavoidable impurities; Ni content High, the alloy cost is high, and the steel plate needs quenching + tempering heat treatment, the manufacturing cost is high and the process is complicated

"A high-strength and high-toughness marine low-temperature steel" (application publication number: CN102851591A), the mass percentage of the chemical composition of the steel plate is: C0.04-0.12%, Si0.20-0.55%, Ni0.05-0.50%, Mn0.6-1.4%, P0.005-0.015%, S≤0.005%, Al0.02-0.07%, Cu0.05-0.40%, N≤0.005%, the balance is Fe and unavoidable impurities, and guarantee Ni / Cu ratio is 1.2-1.5; adding Ni, Cu and other precious alloys, although the ductile-brittle transition temperature is lower than -80°C, but the cost is high

"A steel plate for LPG marine storage tank and its manufacturing method" (application publication number: CN104831181A), the chemical composition of the steel plate is: C0.05-0.095%, Si≤0.30%, Ni0.15-0.80 %, Mn0.70-1.35%, P≤0.015%, S≤0.008%, Al0.020-0.060%, Cu0.15-0.30%, Mo0.15-0.35%, Ti0.008-0.020%, and element Nb One or more of , V, B, Nb0.015-0.065% or V0.030-0.060% or B0.0005-0.0020%, the balance is Fe and unavoidable impurities; add Ni, Cu, Precious alloys such as Mo, the cost of the alloy is high, and the steel plate needs quenching + tempering heat treatment, the manufacturing cost is high and the process is complicated

"A 390MPa grade low-temperature marine steel with excellent toughness" (application publication number: CN103882297A), the mass percentage of the chemical composition of the steel plate is: C0.05-0.12%, Si0.08-0.30%, Mn1.0-1.40 %, P≤0.01%, S≤0.01%, Als0.01-0.05%, Nb0.02-0.04%, Ti0.005-0.020%, the balance is Fe and unavoidable impurities; steel plate structure is polygonal ferrite + acicular ferrite + pearlite + bainite, the volume percentage of bainite ranges from 7-25%; its C content is high, which is not conducive to weldability, and the volume fraction of steel is 7-25% The bainite is an unsteady medium-temperature transformation structure, and the safety is poor when serving at low temperature

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