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On-line cooling control method and device for improving strength and tenacity of high-frequency-welding (HFW) welded pipe after being hot rolled

A strong toughness, welded pipe technology, applied in the field of on-line controlled cooling to improve the strength and toughness of HFW welded pipes after hot rolling, can solve problems such as difficulty in ensuring cooling uniformity, achieve excellent comprehensive performance, reduce cooling rate gradient, and improve comprehensive mechanical properties Effect

Active Publication Date: 2013-06-05
BC P INC CHINA NAT PETROLEUM CORP +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The existing problems are firstly the cooling uniformity control. Due to the particularity of the cross-sectional shape of the steel pipe, it is difficult to ensure the cooling uniformity along the axial direction, circumferential direction and wall thickness direction of the steel pipe during the cooling process; secondly, the cooling process control. Due to the control of cooling The process window is narrow, and the speed range of the hot-rolled and reduced pipe billet of different specifications of HFW welded pipe is wide (0.9m / s~3.6m / s). Within this speed range, all specifications of the hot-rolled reduced pipe billet Rapid and uniform online cooling to a specified temperature range, which requires very strict cooling capacity and precise control of online cooling equipment

Method used

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  • On-line cooling control method and device for improving strength and tenacity of high-frequency-welding (HFW) welded pipe after being hot rolled
  • On-line cooling control method and device for improving strength and tenacity of high-frequency-welding (HFW) welded pipe after being hot rolled
  • On-line cooling control method and device for improving strength and tenacity of high-frequency-welding (HFW) welded pipe after being hot rolled

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0029] Example 1: Ф193.7×7.34mm HFW welded pipe (medium carbon steel material) is cooled online after hot rolling.

[0030] Chemical composition of HFW welded pipe (wt.%): C 0.30, Si 0.25, Mn 1.28, P 0.011, S 0.005, and the rest are Fe and uncontrollable inclusions. A c3 It is 830°C.

[0031] First, HFW welded pipes are hot rolled and reduced in diameter. The HFW welded pipe of Ф193.7×7.34mm is rapidly heated to 1000°C by an intermediate frequency heating furnace, and then enters the thermal tension reducing unit for hot rolling and reduces the diameter to a tube blank of Ф139.7×7.72mm, and then enters the rotary hot saw to saw it into a fixed length Steel pipes of about 10m.

[0032] Secondly, the hot-rolled tube billet is cooled online. The temperature of the steel pipe after hot sawing is 880°C. It passes through a section of air-cooled roller table at a speed of 0.93m / s to reduce the temperature to 820°C, and then enters the V-shaped inclined roller table to make the s...

Embodiment 2

[0035] Example 2: Ф193.7×5.51mm HFW welded pipe (low carbon steel Q345 material) is cooled online after hot rolling.

[0036] Chemical composition of HFW welded pipe (wt.%): C 0.16, Si 0.26, Mn 1.31, P 0.013, S 0.004, and the rest are Fe and uncontrollable inclusions. A c3 It is 840°C.

[0037] First, HFW welded pipes are hot rolled and reduced in diameter. The HFW welded pipe of Ф193.7×5.51mm is rapidly heated to 980°C by an intermediate frequency heating furnace, and then enters the thermal tension reducing unit for hot rolling and reduces the diameter to a tube blank of Ф139.7×6.20mm, and then enters the rotary hot saw to saw it into a fixed length Steel pipes of about 10m.

[0038] Secondly, the hot-rolled tube billet is cooled online. The temperature of the steel pipe after hot sawing is 860°C. It passes through a section of air-cooled roller table at a speed of 1.08m / s to reduce the temperature to 795°C, and then enters the V-shaped inclined roller table to rotate th...

Embodiment 3

[0041] Example 3: Rapid cooling and quenching process of HFW welded pipe after hot rolling. For small-sized, thin-walled and thick steel pipes after hot-stretching, if the water flow and pressure are increased, when the cooling rate is ≥50°C / s (the maximum cooling rate can reach 90°C / s), online quenching after hot-rolling of HFW welded pipes can be realized The ability to provide a new process approach for the development of lower cost and higher steel grade HFW welded pipes in the future.

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Abstract

The invention discloses an on-line cooling control method and a device for improving strength and tenacity of a high-frequency-welding (HFW) welded pipe after being hot rolled. According to the on-line cooling control method and the device for improving the strength and the tenacity of the HFW welded pipe after being hot rolled, firstly, the HFW welded pipe is heated to a temperature 80-200 DEG C higher than the austenitizing phase-transition temperature, and then pipe blank with needed specification is obtained after hot rolling reducing, and then the pipe blank at a temperature still higher than the phase-transition temperature is enabled to rotate and is fast cooled to a needed temperature through the on-line cooling control device. The on-line cooling control device comprises a variable frequency pump, sprayers, nozzles and transmission devices. Each sprayer is of an annular structure. A water inlet pipe of each sprayer is connected with a water outlet of each variable frequency pump. The nozzles are evenly distributed in the inner walls of the sprayers along the circumferential direction. Each transmission devices are arranged between two sprayers and is used for driving the HFW welded pipe to move at a certain speed in a rotary mode. According to the on-line cooling control method and the device for improving the strength and the tenacity of the HFW welded pipe after being hot rolled, cooling uniformity of steel pipes in the circumferential direction, the axial direction, and the wall thickness direction is achieved, the microstructure of welded pipe is refined, the strength and the tenacity of the whole pipe body are improved, good overall performance is achieved, cost is saved at the same time, and resource consumption and energy consumption are reduced.

Description

technical field [0001] The invention belongs to the technical field of high-frequency straight seam welded pipe manufacturing, and in particular relates to an online controlled cooling method and device for improving the strength and toughness of HFW welded pipes after hot rolling. Background technique [0002] In the oil well pipe manufacturing process, whether it is a seamless pipe or a HFW (High Frequency Welding) welded pipe, in order to improve production efficiency and make the change of pipe diameter and wall thickness easy to control, thermal tension reduction technology is generally used. When thermomechanical rolling and drawing are carried out in a heated state, since the structure re-austenites after hot rolling, if the subsequent phase transformation is not controlled, the internal structure of the pipe body will be coarse, resulting in a significant decrease in strength and toughness , It is difficult to meet the requirements of oil and gas drilling and product...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B21B37/74B21B45/02
Inventor 毕宗岳韦奉张锦刚张峰唐俊王涛李敬波李周波王军
Owner BC P INC CHINA NAT PETROLEUM CORP
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