Q345 Z-direction extra-thick low-alloy high-strength structure steel plate and production method thereof

Abstract

The invention discloses a Q345 Z-direction extra-thick low-alloy high-strength structure steel plate with thickness of 50-70mm. The steel in the steel plate comprises the following chemical components in percentage by weight: 0.15-0.16% of C, 0.27-0.32% of Si, 1.39-1.45% of Mn, 0.010-0.013% of P, 0.001-0.007% of S, 0.029-0.049% of Al, 0.056-0.064% of V, 0.013-0.016% of Ti, 0.012-0.014% of Nb and the balance of Fe, wherein the carbon equivalent is 0.40-0.42. Meanwhile, the invention also discloses a production method of the Q345 Z-direction extra-thick low-alloy high-strength structure steel plate. With good comprehensive performance and high impact toughness, the Q345 Z-direction extra-thick low-alloy high-strength structure steel plate disclosed by the invention particularly has the advantages of good Z-direction performance, stable product quality, high product percent of pass and the like.

Description

technical field [0001] The invention relates to the technical field of metallurgical industry steel plates and processing technology thereof, in particular to a Q345 series ordinary carbon structural steel plate with a thickness of 50-70 mm and a production method thereof. Background technique [0002] In the welded steel structure, when the thickness of the steel plate is not less than 40mm and bears the tensile force along the thickness direction of the plate, in order to avoid lamellar tearing during welding, it is necessary to use steel that resists lamellar tearing (usually referred to as "Z-direction steel"). "). Thick plates have the problem of lamellar tearing, so a Z-direction performance test is proposed. The steel plate and section steel are formed by rolling. Generally, the steel used in the multi-story steel structure is hot-rolled. Hot rolling can destroy the casting structure of the steel ingot and refine the grain of the steel. Bubbles and cracks formed dur...

AI Technical Summary

Problems solved by technology

For the steel rolling process, as the thickness of the steel plate increases, the rolling feed thickness ratio (the ratio of the controlled rolling thickness to the finished product thickness, the feeding thickness ratio = the controlled rolling thickness ÷ the finished product thickness, the same below) decreases, and the temperature drops slowly during the rolling process. , cooling strength after rolling and other factors are difficult to increase, resulting in increased difficulty in controlled rolling of extra-thick steel plates, product impact toughness tends to deteriorate gradually, product performance and quality are unstable, and the pass rate of preliminary test performance is less than 90%.

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