High-nitrogen and low-alloy ship plate steel high in low-temperature toughness and manufacture method thereof

Abstract

The invention discloses high-nitrogen and low-alloy ship plate steel high in low-temperature toughness and a manufacture method thereof. Components of the high-nitrogen and low-alloy ship plate steelhigh in low-temperature toughness include C, Si, Mn, P, S, V, Ti, Als, N and the balance Fe and impurities, and the content of the component elements mentioned above must simultaneously meet the following relations that V+Ti >=0.070 and (V+Ti)/N >=6.95. According to the manufacture method, combination reinforcement of carbonitride is achieved through the two alloy elements, namely, V and Ti, underthe high N content, and by means of control of the rolling and cooling process, the large amount of carbonitride is formed; the carbon content in the steel is effectively decreased, and the high-strength and high-tenacity ship plate steel is manufactured. The yield strength of steel plates is larger than or equal to 370 MPa, the elongation A is larger than or equal to 25%, and the impact absorbing energy at the temperature of -40 DEG C is larger than or equal to 200 J. The ship plate steel is suitable for constructing ship and ocean engineering steel structures with high requirements for strength and tenacity, is simple in component design, short in technological process and low in production cost, and has good economic benefits and social benefits.

Description

Technical field [0001] The invention relates to the technical field of manufacturing ship plate steel, in particular to a ship plate steel with high nitrogen and low alloy low temperature toughness and a manufacturing method thereof. Background technique [0002] High-strength and toughness ship plate steel is generally manufactured by adding microalloying elements for controlled rolling or normalizing heat treatment. Most of the three microalloying elements of Nb, V and Ti are used for composite strengthening. Since there is almost no niobium ore in China, all niobium alloys need to be imported. The cost price is high, and it is easily affected by international trade. [0003] In the prior art, the Chinese invention patent application (application number 201110213957.0, application date 2011.07.28) discloses "a high-strength and high-toughness ship plate steel and its TMCP production process", which is characterized in that it contains 0.04~0.08% C , Si0.15~0.40%, Mn1.30~1.55%, P...

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Problems solved by technology

[0006] The purpose of the present invention is to propose a ship plate steel with high nitrogen and low alloy low temperature toughness and its manufacturing method to solve the existing problems of high alloy content of ship plate steel, long manufacturing process, large energy consumption and high manufacturing cost. The thickness specification of plate steel is 10~50mm, the yield strength at room temperature is ≥370MPa, the elongation A is ≥25%, and the impact absorption energy at -40°C is ≥200J. It is used for the construction of steel structures for ships and marine engineering

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