Rolling process for refining M-A components in low-carbon bainite steel

Abstract

The invention discloses a rolling process for refining M-A components in low-carbon bainite steel and belongs to the technical field of steel production. The rolling process comprises three steps of heating, rolling and cooling. The rolling process has the following beneficial technical effects: (1), the average size of the M-A components in the low-carbon bainite steel is not greater than 1.5 microns; (2), the average value of KV2 impact energy at 40 DEG C below zero of typical positions (1 / 4 position and 1 / 2 position) in a thickness direction of a low-carbon bainite steel plate with high thickness of more than 50mm is not less than 200J, and the difference value between single values is not greater than 20J; (3), the yield strength of typical positions (1 / 4 position and 1 / 2 position) in the thickness direction of the low-carbon bainite steel plate with high thickness of more than 50mm is 521-595MPa, the tensile strength is 652-710MPa, the yield ratio is 0.79-0.85, and the elongation rate is 19-23%; and (4), the preparation scheme of the low-carbon bainite steel is easy to implement, the production process is easy to control, low-cost stable batch industrial production can be realized, and the construction requirements of main bearing structures such as bridges, buildings, maritime work, pipelines, wind power towers and the like on high-thickness and high-strength steel can be met.

Description

technical field [0001] The invention belongs to the technical field of iron and steel manufacturing, and particularly relates to a rolling process for refining M-A components in low-carbon bainite steel. The steel plate produced by this process has excellent low-temperature toughness and performance stability, and is well uniform in thickness direction . Background technique [0002] In recent years, low-carbon bainitic steel has been widely used in bridges, construction, marine engineering, pipelines, wind power towers and other fields due to its excellent strength, toughness and weldability. In the actual production process of low-carbon bainite steel, phase transformation occurs in the continuous cooling process to form all or a certain amount of granular bainite room temperature structure. When the rolling or cooling penetration is insufficient, especially for steel plates with a thickness of more than 50mm, the size of the martensite-austenite component (M-A component)...

AI Technical Summary

Problems solved by technology

Although the coarse M-A components can be decomposed by tempering heat treatment to achieve the purpose of improving the low-temperature toughness at 1 / 4 of the thickness of the plate, but due to insufficient rolling and cooling penetration in the center, it is difficult to improve the low-temperature toughness of the center, and the thickness cannot be completely solved. Thickness performance uniformity problem

[0007] The authorized announcement numbers are CN1323187C, CN103451537B and CN103451561B and other invention patents. By adjusting the alloy composition and controlling the addition of lower elements such as C, Si, Mn or Cr, to reduce the brittle phase of M-A components, it is beneficial to improve the impact toughness of the base metal , but the tensile strength is often insufficient, the yield ratio is high, and the strength does not meet the service requirements

[0008] It can be seen that in the current research, most of the alloy composition or heat treatment process is used to regulate the M-A component, and the research on the regulation of the M-A component through the rolling process is not deep enough, resulting in the strength and toughness, performance stability and thickness of the thick gauge steel plate. There are still many deficiencies in the control of uniformity of performance, and the development of related preparation technology is urgently needed

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