Q345D steel with thickness of 16 mm and production method thereof

Abstract

The invention provides a Q345D steel with a thickness of 16 mm and a production method thereof. The Q345D steel comprises the following elements by mass: 0.14 to 0.18% of C, 0.90 to 1.03% of Mn and 0.012 to 0. 020% of Nb. In the process of production, the surface temperature of a casting blank at the ending moment of heating is controlled within the range of 1100-1150 DEG C, heating time is no less than 8 min / cm; an initial rolling temperature is 1080-1100 DEG C, a first-stage finish rolling temperature is more than 1000 DEG C, and a second-stage finish rolling temperature is no more than 890DEG C; in the second stage, the temperature-waiting thickness of the casting blank 2.5 times or more the thickness of a finished steel sheet, and the finish rolling temperature is controlled within the range of 810 to 850 DEG C; an initial cooling temperature is no less than 740 DEG C, and a finish cooling temperature is 650+ / - 20 DEG C. The production method of the invention successfully producesthe Q345D low-alloy high-strength steel under the premise of ensuring low production cost, and the mechanical properties and internal quality of the produced steel plate meet requirements prescribedin GB / T1591.

Description

technical field [0001] The invention relates to low-alloy high-strength steel and a production method thereof, in particular to a Q345D steel with a thickness of 16mm and a production method thereof. Background technique [0002] Q345D is a low-alloy high-strength steel with good comprehensive mechanical properties and process properties. It is widely used in engineering fields such as steel structures and wind towers. Products with a thickness of 16mm are routinely used. Domestic medium plate factories produce steel plates of this specification, and the composition design mainly uses C, Mn and other elements, of which the C content is about 0.11-0.17wt%, and the Mn content is about 1.30-1.60wt%. The composition of the steel grade is: C: 0.15wt%, Mn: 1.39wt%, Al: 0.048wt%; the composition of the 16mm thick Q345D steel grade of Jiuquan Iron and Steel Company is: C: 0.11-0.17 wt%, Mn: 1.30-1.60 wt% %; Anyang Iron and Steel Company: C: 0.12-0.14 wt%, Mn: 1.35-1.45 wt%; control...

AI Technical Summary

Problems solved by technology

The content of Mn element in the existing composition ratio is relatively high, resulting in high production costs, which is not conducive to the improvement of enterprise benefits

In order to reduce the production cost of Q345D, some enterprises reduce the content of Mn element and add Nb element at the same time to ensure the product performance through the effect of Nb element on grain refinement; but in order to improve the effect of grain refinement, the amount of Nb element added is generally 0.020wt % or more, although the Mn element content is reduced, the addition of more than 0.020wt% Nb element offsets the cost of reducing the Mn element content, resulting in high production costs

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