Production method for thin specification Q370qE steel plate

Abstract

The invention discloses a production method for a thin specification Q370qE steel plate. The thickness of the steel plate is 6-10 mm. Steel comprises chemical components including, by weight percent,0.08-0.12 of C, 0.15-0.40 of Si, 1.20-1.60 of Mn, smaller than or equal to 0.02 of P, smaller than or equal to 0.01 of S, 0.01-0.05 of Als, 0.010-0.020 of Nb, 0.006-0.025 of Ti, smaller than or equalto 0.30 of Cr, smaller than or equal to 0.30 of Ni, smaller than or equal to 0.20 of Pcm, and the balance Fe and inevitable impurity elements. According to the production method, the single-phase austenite area rolling and 1-2-pass two-phase area rolling technology is adopted, a mixed structure including 40%-60% of air-cooled ferrite grains with the grain size being the eighth-tenth level, 30%-45%of shape change induction ferrite grains with the grain size being the tenth-twelfth level and 10%-15% of pearlite is obtained. The produced thin specification bridge structure steel plate can combine good impact toughness and the low yield ratio under limitation of Pcm, meanwhile, the production cost is low, the technology is simple and controllable, and the plate shape is easy to control.

Description

technical field [0001] The invention belongs to the technical field of low-alloy structural steel production, and in particular relates to a production method of a thin-gauge Q370qE steel plate. Background technique [0002] High strength and toughness, low yield ratio, and easy welding are the basic performance requirements of bridge steel structures. With the development of economy and metallurgical technology, the performance requirements of bridge steel structures are getting higher and higher. Compared with GB / T 714-2008, the new standard of Chinese national standard GB / T 714-2015 increases the impact energy from not less than 47J to not less than 120J, and the recommended yield ratio is not more than 0.85, and the carbon equivalent CEV and welding crack The requirements for the sensitivity index Pcm are more stringent. For example, for thermomechanical rolling Q370qE, if the carbon content is not more than 0.12%, the Pcm is required to be not more than 0.20%. [0003...

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Problems solved by technology

Although the patents CN101660099B, CN102080192B, and CN103866204B have comprehensively considered the strength, toughness, yield ratio and weldability of the material, and can meet the requirements of Pcm≤0.20%, impact energy at -40°C≥120J, and yield ratio≤0.85, but the patent CN101660099B adds More precious metals such as Ni, Cr, Mo, Cu are added, and the cost of the alloy is high; the patent CN102080192B adopts an off-line heat treatment process, the manufacturing process is complicated, and the production cycle is long; the patent CN103866204B obtains a dual-phase structure through an accelerated cooling process, and the accelerated cooling process Increases the difficulty of shape control, especially for thin gauge medium and thick plates

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