Method for producing high heat input welding Q345-level steel plate
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A large heat input welding and production method technology, applied in the field of iron and steel products, to achieve good performance, good cold bending performance, suitable for mass production
Active Publication Date: 2013-10-09
ANGANG STEEL CO LTD
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In view of the deterioration of the toughness of the heat-affected zone of the steel plate with a ferrite-pearlite structure as the main body, through adjustment and improvement of the steel plate smelting, rolling, heat treatment and other production processes, measures are taken to effectively suppress the coarse grains of the HAZ and suppress Growth of Austenite Grain in High Temperature Zone Improves Toughness of Welding Heat-Affected Zone
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Embodiment 1
[0021] The present invention is a production method of large heat input welding Q345 grade steel plate, and its technological process includes smelting, continuous casting, heating, dephosphorization, controlled rolling and controlled cooling, hot straightening, stacking and slow cooling, and fire cutting to finished products, aiming at three Key points to be controlled: smelting composition design, controlled rolling and controlled cooling, and cooling after final rolling. The specific controls are as follows
[0022] 1) Smelting composition design (wt%): C: 0.12%, Si: 0.30%, Mn: 1.30%, Nb: 0.2%,, Ti: 0.15%, P≤0.01%, S≤0.003%, [N]0.05 %, CEV0.35, the rest is iron and unavoidable trace impurities; where Ti / [N]=3;
[0023] During smelting, the molten steel is first smelted in an electric furnace and then sent to an LF refining furnace for refining. During the refining process, white slag is strengthened for secondary desulfurization to ensure that S≤0.003%.
[0024] 2) Casting...
Embodiment 2
[0031] The present invention is a production method of large heat input welding Q345 grade steel plate. The technological process includes smelting, continuous casting billet, heating, dephosphorization, controlled rolling and controlled cooling, hot straightening, stacking and slow cooling, cutting and inspection to finished products. The key points are controlled: smelting composition design, controlled rolling and controlled cooling, and cooling after final rolling. The specific control is as follows
[0032] 1) Smelting composition design (wt%): C: 0.13%, Si: 0.40%, Mn: 1.40%, Nb: 0.3%,, Ti: 0.10%, P≤0.01%, S≤0.003%, [N]0.04 %, CEV0.34, the rest is iron and unavoidable trace impurities; where Ti / [N]=2.5;
[0033] During smelting, the molten steel is first smelted in an electric furnace and then sent to an LF refining furnace for refining. During the refining process, white slag is strengthened for secondary desulfurization to ensure that S≤0.003%.
[0034] 2) Casting: Aft...
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Abstract
The invention relates to the field of iron and steel products and in particular relates to a method for producing a high heat input welding Q345-level steel plate. The process flow comprises the following steps of: smelting, continuous casting, heating, phosphorous removal, controlled rolling and cooling, thermal straightening, stacking, slow cooling, and cracking off to obtain the finished product. Three key points, such as design of smelting components, controlled rolling and cooling and cooling after final rolling, are controlled, wherein in the design of the smelting components, Ti / (N)is equal to 2.4-3.2. Compared with the prior art, the method has the beneficial effects that according to filed practice, the high heat input welding Q345-level steel plate produced by the method has good performance of a welded joint, the sample fracture occurs on a base metal, and the phenomenon that the welded joint is softened is avoided; along with increase of heat input, lateral impact values in an HAZ area at the temperatures of -20 DEG C and -40 DEG C are reduced; the cold bending performance is good, and the mechanical property and welding performance completely exceed the standard requirements; moreover, the method has the advantages of short production flow, low production cost, suitableness for mass production and the like.
Description
technical field [0001] The invention relates to the field of iron and steel products, in particular to a production method for large heat input welding Q345 grade steel plates. Background technique [0002] At present, steel mills at home and abroad are conducting research on high-energy-input welding steel, but none of them has formed a special steel brand for high-energy-input welding, but only as a characteristic of the variety of steel to promote and apply. Traditional methods such as manual welding and submerged arc welding are used for welding, and the line energy is generally 30~60KJ / cm, and welding methods such as multi-layer welding, preheating, and backing plates greatly reduce construction efficiency. With the development of large-scale and thicker steel structures in the future, in order to improve production efficiency, it is an inevitable trend to adopt >80KJ / cm electroslag welding, gas-electric vertical welding and other high-input energy welding processes....
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