Thick steel plate capable of being welded under large heat input and method for manufacturing the same

Abstract

A thick steel plate that can be welded with large heat input, its composition is (percentage by weight): C 0.010%~0.020%, Si 0.10%~0.30%, Mn 1.80%~2.30%, P≤0.010%, S≤0.003%, Nb 0.015%~0.030%, Als 0.025%~0.050%, Ti 0.010%~0.020%, N0.003%~0.006%, REM 0.001%~0.005%, Mg 0.002%~0.006%, B 10ppm~35ppm, excess iron . The invention removes the alloying of precious elements such as Ni, Cr, Mo, Cu, etc., especially the alloying of Ni elements, and optimizes the TMCP process. While obtaining excellent low-temperature toughness of the base metal steel plate, the HAZ of the large input energy welding The low temperature toughness is also excellent; this not only reduces the manufacturing cost, shortens the production cycle, but also reduces the difficulty of production organization, and at the same time eliminates the difficulty of recycling a large amount of scrap steel containing Cu and Ni, and realizes the green and environmental protection of the manufacturing process.

Description

technical field [0001] The present invention relates to an extremely low-carbon TMCP thick steel plate which can be welded with large input energy in an extremely low-C-high-Mn-Nb-B alloy system to obtain yield strength ≥ 420MPa, Charpy impact toughness ≥ 100J at -60°C Production method. Background technique [0002] As we all know, low-carbon (high-strength) low-alloy steel is one of the most important engineering structural materials, widely used in oil and gas pipelines, offshore platforms, shipbuilding, bridges, pressure vessels, building structures, automobile industry, railway transportation and machinery manufacturing . The properties of low-carbon (high-strength) low-alloy steel depend on its chemical composition and the process system of the manufacturing process, among which strength, toughness and weldability are the most important properties of low-carbon (high-strength) low-alloy steel, which are ultimately determined by the finished steel state of the microst...

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Problems solved by technology

The Firth (1986) international Symposium and Exhibit on Offshore Mechanics and Arctic Engineering, 1986, Tokyo, Japan, 354; "DEVELOPMENTS IN MATERIALS FOR ARCTIC OFFSHORE STRUCTURES" (Sumitomo Metal 2)], to ensure the low-temperature toughness of the base steel plate; but the welding heat The low-temperature toughness of the affected zone (HAZ) is generally difficult to achieve, especially when the welding line energy is large, the low-temperature toughness of the HAZ is seriously deteriorated; a large number of patent documents only explain how to realize the low-temperature toughness of the base steel plate, and how to obtain excellent welding HAZ low-temperature The toughness is less explained, especially how to ensure the low-temperature toughness of HAZ when high-energy-input welding is used, and in order to ensure the low-temperature toughness of the steel plate, a certain amount of Ni element is generally added to the steel. Zone (HAZ) low temperature toughness is rarely able to reach -60 ℃

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