Ti-microalloyed Q345B steel plate and production method thereof

Abstract

The invention discloses a Ti-microalloyed Q345B steel plate and a production method thereof. The Ti-microalloyed Q345B steel plate comprises the following chemical components by weight: 0.15 to 0.19% of C, 0.9 to 1.15% of Mn, no more than 0.010% of S, no more than 0.015% of P, 0.2 to 0.3% of Si, 0.01 to 0.02% of Als and 0.035 to 0.045% of Ti, with the balance being iron and unavoidable impurities. CEV is no more than 0.37%. According to the invention, on the basis of C and Mn steel, the content of Mn is reduced and microalloying reinforcement effect of Ti is utilized, so the mechanical properties of the steel plate meet requirements of Q345B, and the steel plate has better welding performance compared with conventional steel plates prepared from C and Mn; and the Ti-microalloyed steel plate has lower cost and is more suitable for promotion and application. The method provided by the invention employs controlled-rolling controlled-cooling technology for rolling and utilizes microalloying reinforcement of Ti, so the produced steel plate has yield strength of 378 to 401 Mpa, tensile strength of 488 to 522 Mpa, elongation percentage of 21.5 to 28.5%, impact toughness at 20 DEG C of 164 to 213 J and carbon equivalent of no more than 0.37% and meets requirements prescribed in Standard GB / T1591-2008 in China.

Description

technical field [0001] The invention relates to a low-alloy high-strength structural steel, in particular to a Ti microalloyed Q345B steel plate and a production method thereof. Background technique [0002] Q345B belongs to the series of low-alloy high-strength structural steel products. It is the most commonly used steel product in China at present. It is widely used in many fields such as construction, bridges, and machinery manufacturing. At present, domestic steel mills mainly have two ideas for Q345B composition design. One is to adopt C and Mn composition system, that is, C 0.14-0.17%, Mn 1.4-1.55%; this is a Q345B composition system with the lowest cost. The biggest defect of steel is that the carbon equivalent is too high, between 0.38 and 0.43%. As we all know, the carbon equivalent CEV is an important indicator to measure the welding performance of steel products. The lower the carbon equivalent, the better the welding performance of the material. The other is to...

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Problems solved by technology

The other is to adopt the composition system of C, Mn, and Nb, that is, C 0.14-0.17%, Mn 0.9-1.1%, and Nb 0.01-0.03%. This composition system is relatively good in comprehensive mechanical properties, but it is expensive to add The alloying element Nb increases the cost a lot

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