Ultra-low temperature steel in great heat input welding and manufacturing method of steel

Abstract

The invention discloses ultra-low temperature steel in great heat input welding and a manufacturing method of the steel. The steel disclosed by the invention comprises the following components in percent by weight: 0.040-0.090% of C, less than or equal to 0.15% of Si, 1.10-1.50% of Mn, less than or equal to 0.013% of P, less than or equal to 0.0020% of S, 0.10-0.30% of Cu, 0.05-0.20% of Ni, 0.008-0.020% of Nb, less than or equal to 0.010% of Als, 0.008-0.013% of Ti, 0.0035-0.0065% of N, 0.001-0.004% of Ca, 0.0008-0.0020% of B and the balance of Fe and inevitable impurities. By adopting the simple combined design of alloy elements in the steel disclosed by the invention, the TMCP (Thermal Mechanical Control Processing) technology is optimized without the requirement of adding a great number of noble elements such as Ni and Cu, the excellent patent steel plate low-temperature tenacity is acquired and simultaneously the low-temperature tenacity of the HAZ (Heat Affected Zone) during large line energy welding is also excellent; and the uniform and excellent mechanical property, good welding property and marine atmosphere corrosion resistance are acquired, so that the steel disclosed by the invention is specially applicable to wind tower structures on the sea, low-temperature pressure vessels, ocean platforms and bridges.

Description

technical field [0001] The present invention relates to low-carbon low-alloy steel, in particular to high-heat-input welding ultra-low temperature steel and its manufacturing method. The yield strength is ≥355MPa, the tensile strength is ≥490MPa, and the impact toughness at -60°C is ≥100J, and it can be welded with large input energy . 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, bridge structures, boiler containers, building structures, automobile industry, railway transportation and machinery manufacturing. The performance of low-carbon (high-strength) low-alloy steel depends on its chemical composition and manufacturing process, among which strength, toughness, plasticity and weldability are the most important properties of low-carbon (high-strength) low-alloy steel, which are ultimately determin...

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Problems solved by technology

"Steel Plates for Offshore Platform Structures Used in Ice Sea Areas" (Japanese), Iron and Steel Research, 1984, No. 314, 19-43], to ensure that the base metal steel plate has excellent low-temperature toughness, using <100KJ / cm heat input welding When welding, the toughness of the heat-affected zone (HAZ) can also reach -60℃Akv≥34J; but when welding with large input energy (≥200KJ / cm), the low-temperature toughness of the welding heat-affected zone (HAZ) is generally difficult to achieve, and the heat-affected zone (HAZ) severe deterioration of low temperature toughness

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