80 kg-grade low-carbon equivalent low-crack sensitivity large-thickness hydroelectric steel and manufacturing method thereof

Abstract

The invention relates to a 80 kg-grade low-carbon equivalent low-crack sensitivity large-thickness hydroelectric steel. A steel plate takes iron as a basic element and comprises the following chemicalelements of, by mass percent, 0.07-0.12% of C, 0.05-0.35% of Si, 0.8-1.5% of Mn, less than or equal to 0.010% of P, less than or equal to 0.005% of S, 0.2-0.7% of Cr, 0.3-0.6% of Mo, 0.5-1.8% of Ni,less than or equal to 0.4% of Cu, 0.015-0.06% of Alt, less than or equal to 0.1% of Nb, 0.02-0.05% of V, 0.001-0.004% of B and the balance Fe and impurity elements. The manufacturing method of the hydroelectric steel comprises the following working procedures such as molten iron pretreatment, converter smelting, LF and RH refining, continuous casting, heating, rolling, flaw detection and quenchingtempering. According to the hydroelectric steel and the manufacturing method, the steel plate with the thickness capable of reaching 150 mm is manufactured by adopting a 370-mm continuous casting blank, the yield strength is 690 Mpa or above, the tensile strength is in the range of 770-930 Mpa, the elongation percentage is not less than 15%, the Charpy impact power is larger than or equal to 100Jat the -40 DEG C, 5% aging impact power is larger than or equal to 100J at the -20 DEG C, D is equal to 3a, and 180-degree cold bending non-cracking is achieved; and the comprehensive performance isexcellent, the production process is simple and convenient, the cost is low, and the yield is high.

Description

technical field [0001] The invention relates to the technical field of metal materials, and relates to an 80kg grade low-carbon equivalent low-crack sensitivity large-thickness hydroelectric steel and a manufacturing method thereof. Background technique [0002] Hydropower is the clean energy that my country is currently focusing on developing, and the construction of hydropower stations is inseparable from steel materials. Among them, the tongue plate and volute required by the generator set, the core part of the hydropower station, put forward more stringent requirements for steel materials. It not only requires that the steel plate is easy to weld, high low temperature impact toughness, but also has high strength, but good weldability means that the material has a low carbon equivalent, and the low carbon equivalent industry limits the strength of the material, so it must be Balance the two in this contradictory relationship. Generally, the yield strength of high-streng...

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Problems solved by technology

[0003] The Chinese invention patent with the patent publication number CN101418418A proposes a steel plate with a yield strength of 690Mpa and its manufacturing method with low crack sensitivity, and the preparation method of the steel plate mentioned in the patent publication number CN103292339A. The method of manufacturing high-strength steel plates for station pressure pipelines, but the thickness of the largest steel plates manufactured by this method is only 60mm, which is far from meeting the requirements of steel for hydropower stations

[0004] The manufacturing method of the steel plate with a yield strength of 800Mpa and low welding crack sensitivity proposed in the patent publication number 200710094177.2, the steel plate produced by the controlled rolling and controlled cooling technology can only guarantee the low-temperature impact of -20°C, and cannot guarantee the impact of the steel plate at a lower temperature by the hydropower station. The reserves of low-temperature toughness cannot meet the needs of the hydropower industry for steel plates

[0005] Patent Publication No. CN2005100191165.4 discloses a method for manufacturing a low welding crack sensitivity steel plate with a yield strength of 690Mpa. Although it has good low welding crack sensitivity, its yield strength is only 500Mpa, which cannot meet the current requirements. Requirements for high-strength steel in the hydropower industry

[0006] The patent publication number is a kind of high-strength hot-rolled steel with a yield strength of 700Mpa mentioned in the invention patent of CN103215516A. Its carbon content is 0.15-0.40%, Si: 1.0-2%, and elongation>10%. Requirements for steel plates in hydropower stations

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