A production process for hot-rolled pipeline steel in a single-stand furnace coil mill

Abstract

The invention discloses technology for producing hot-rolled pipeline steel of roll mill with a single frame furnace. Tapping temperature of steel billet is more than or equal to 1100 DEG C; rolling temperature of the second process is no more than 900 DEG C, and thickness of billet to be waited in temperature is less than or equal to 3.3 hours; pass rolling reduction rate in the second last is less than or equal to 9% and no more than 13%, the final pass rolling reduction rate is 0%; rolling speed of the second last pass of the final rolling is reduced to enable the final rolling temperature to be 780-820 DEG C; after the water temperature is 695-740 DEG C, online speed casting steel without rolling reduction rate is finished and the steel is cooled in a layer flow cooling system; temperature uniformity of rolled piece entering water and temperature uniformity of flat cooling are guaranteed; before entering a straightener, the rolled piece is produced with plastic deformation requirement no less than 80% according to thickness direction; and roll gaps of an entrance and an exit of the straightener are arranged. When rolling the pipeline steel for a special purpose, the invention can control steel plate shape and improve economic benefit while meeting performance requirement of the final product.

Description

technical field [0001] The invention belongs to the field of steel rolling, and relates to a rolling process for hot-rolling special-purpose pipeline steel by a single-stand furnace rolling mill. Background technique [0002] At present, when the thickness of 220mm, 180mm and 150mm is used to flat-roll special-purpose pipeline steel, the performance and shape of the plate need to be controlled at the same time. In order to ensure the performance, there are extremely strict and accurate requirements on the final rolling temperature, water entry temperature and red return temperature. For example, for large deformation resistant pipeline steel X70HD, the final rolling temperature of the penultimate pass is 780°C~820°C, and the temperature is controlled between 695°C~740°C before the steckel mill to obtain part of proeutectoid ferrite , followed by laminar cooling for accelerated cooling. This requires the second-to-last pass of the steckel mill to reduce the rolling speed to...

AI Technical Summary

Problems solved by technology

Because the length of the original billet used is more than 7m, no matter how to increase the heating temperature or rolling speed, etc., because the rolled piece is too long in the finishing rolling stage, the rolling process will become thinner and thinner with the rolling process of the steel plate, and the steel plate will be thinner and thinner. The temperature drop will become faster and faster, resulting in extremely uneven temperature distribution along the length of the rolled piece, which increases the difficulty of controlling the shape and performance of the rolled piece

Therefore, the development of a rolling process for special-purpose pipeline steel is a problem that needs to be solved urgently, especially when the length of the billet is greater than 7m, the performance and shape of the rolled piece will be caused by excessive temperature difference and rapid temperature drop. series of questions

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