High-strength and high-toughness steel plate for low-cost and high linear energy welding

Abstract

The invention discloses a high-strength and high-toughness steel plate for low-cost and high linear energy welding, comprising the following components in percentage by weight: more than 0.06 and not more than 0.15 percent of C, more than 0.05 percent and not more than 0.25 percent of Si, not less than 1.30 percent and less than 1.80 percent of Mn, less than 0.01 percent of P, less than 0.005 percent of S, more than 0.02 percent and not more than 0.10 percent of Al, not less than 0.006 percent and not more than 0.02 percent of N and more than 0.05 percent and not more than 0.02 percent of Ti; meanwhile, the requirements that the Ti / N is not more than 3.42, the thickness of the steel plate is 20-40mm, the yield strength reaches over 400MPa and the tensile strength is over 500MPa are met; the invention is suitable for a high-strength and high-toughness steel plate of which the welding line energy is 200-400kJ / cm; and the -20oC average impact energy of a steel plate HAZ (Heat Affected Zone) is over 200J. According to the high-strength and high-toughness steel plate disclosed by the invention, by increasing the content of nitrogen in the steel, the low-temperature toughness of a high linear energy welding heat affected zone of the steel plate is greatly improved.

Description

technical field [0001] The invention relates to a low-alloy high-strength steel, in particular to a low-cost high-input energy welded high-strength and high-toughness steel plate. Background technique [0002] Low-alloy steel (including micro-alloy steel) is one of the most widely used structural materials in engineering applications, and is widely used in oil and gas pipelines, shipbuilding, bridges, high-rise buildings, pressure vessels, oil storage tanks and other industries. In order to improve production efficiency, the above-mentioned industries have higher and higher requirements on the weldability of steel plates, especially the high-energy-input weldability. However, high-energy-input welding is likely to bring about a serious problem, that is, the welding heat-affected zone around the weld ( The toughness of Heat Affected Zone (hereinafter referred to as HAZ) is seriously deteriorated, and brittle fracture is very easy to occur. For traditional steel plates su...

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Problems solved by technology

[0003] Precious metal elements such as Ni, Mo, Nb, and V are added to varying degrees in the existing steel sheets for high heat input welding. For example, Chinese patent CN200410017255.5 and Chinese patent CN200580012110.9 add a large amount of Ni, Mo , Nb, V and other noble metal elements, although these noble metal elements can improve the welding performance of the steel plate for high heat input welding to a certain extent, but these precious metals greatly increase the production cost; in terms of welding line energy, the existing large line energy The welding line energy in the steel plate for welding is low, between 50-150kJ / cm, and the peak temperature of welding heat simulation is low (usually at 1350 o C), welding heat simulation t 8 / 5 The cooling time is relatively short, less than 200s

Although the Chinese patent CN200580012110.9 can reach the welding line energy of 200-1000kJ / cm, but from the perspective of alloy design, too many alloying elements are added, such as the addition of precious metal Ni at least 0.8%, in addition to varying degrees of addition Precious metals Nb, V, Mo, etc., and the patent uses an oxide metallurgy process, the key technology of which lies in the steelmaking process, which also greatly increases the production cost

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