High-precision thermal expanding method for high-strength steel pipes

A high-precision, high-strength technology, which is applied in the field of thermal processing, can solve the problems that the normal temperature diameter expansion process cannot meet the requirements and use requirements, and achieve simple and practical expansion methods, increase the scope of use, and improve roundness and straightness Effect

Active Publication Date: 2011-09-21
湘潭华进重装科技股份有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, with the improvement of steel pipe material grade and steel pipe thickness, especially in aerospace and military fields, σ b ≥1640MPa, σ 0.2 The diameter expansion of ultra-high-strength alloy steel pipes ≥1400MPa, the normal temperature expansion process can no longer meet the use requirements
Moreover, the accuracy requirements for steel pipes in the aerospace and military fields are also very strict, and the normal temperature diameter expansion process cannot meet the requirements.

Method used

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  • High-precision thermal expanding method for high-strength steel pipes
  • High-precision thermal expanding method for high-strength steel pipes
  • High-precision thermal expanding method for high-strength steel pipes

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0027] Embodiment 1 adopts the steel pipe of T250 material, and the mechanical property of material: tensile strength σ b 1700MPa, yield strength

[0028] σ 0.2 It is 1600MPa, the wall thickness is 5mm, the inner diameter of the steel pipe is φ395.7mm, the length is 970mm, the roundness is ≤4.6mm, and the straightness is ≤2.6mm / m.

[0029] The manual spray gun evenly sprays graphite emulsion on the surface of the outer module of the expanding machine; the pipe delivery trolley sends the steel pipe into the heating furnace, and after filling with argon for 10 minutes, 2500Hz intermediate frequency heating, heating at room temperature to 200°C within 3 minutes, keeping it warm for 5 minutes, and removing water Impurities such as steam and oil. Rapidly heat up to 700°C in 4 to 6 minutes, stop heating after 2 minutes of heat preservation, open the movable furnace door, move the expanding machine forward into the heating furnace, insert the outer module into the steel pipe, expan...

Embodiment 2

[0030] Embodiment 2 adopts the tapered steel pipe of T300 material, and the mechanical property of material: tensile strength σ b 2100 MPa, yield strength σ 0.2 It is 1900 MPa, the wall thickness is 4 mm, the inner diameter of the tapered steel pipe: small head φ393.1mm, large head φ430.1mm, length 940mm, roundness ≤ 4.3mm, straightness ≤ 2.8mm / m.

[0031] Spray graphite emulsion on the surface of the outer module with a manual spray gun; send the steel pipe into the heating furnace with argon for 10 minutes, and then heat it with 3000 Hz intermediate frequency, heat it at room temperature to 200°C within 2 minutes, and keep it warm for 4 minutes to remove water vapor and oil stains, etc. For impurities, quickly heat to 800°C in 5-6 minutes, keep warm for 2 minutes, and stop heating. Open the door of the movable heating furnace, and the expanding machine moves forward to enter the heating furnace. The outer module is inserted into the steel pipe, and the inner diameter of the...

Embodiment 3

[0032] Embodiment 3 adopts the tapered steel pipe of 16Co14Ni10Cr2Mo material, and material mechanical properties: tensile strength σ b 1749 MPa, yield strength σ 0.2 1598 MPa, wall thickness 8 mm, inner diameter of steel pipe: small head φ420.2mm, large head φ455.3mm, length 940mm, roundness ≤ 5.0mm, straightness ≤ 3.0mm / m.

[0033] Spray graphite emulsion on the surface of the outer module with a manual spray gun; send the steel pipe to the heating furnace with argon for 10 minutes, and then heat it with 2000 Hz intermediate frequency, heat it at room temperature to 200°C within 4 minutes, and keep it warm for 8 minutes to remove water vapor and oil stains, etc. Impurities. Rapidly heat to 750°C in 7 minutes, keep warm for 2 minutes, and stop heating. Open the movable heating furnace door, the expanding machine moves forward to enter the heating furnace, the outer module is inserted into the steel pipe, and the inner diameter of the expansion type is expanded to φ423mm for...

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Abstract

The invention discloses a high-precision thermal expanding method for high-strength steel pipes. The method comprises the processing steps of preparation of an expanding machine, furnace heating, thermal expanding, external furnace cooling and stripping. The steel pipes to be expanded are charged into a heating furnace and heated to the temperature of between 600 and 800 DEG C, wherein according to the steel pipes, the tensile strength sigma b is between 1,640 and 2,100MPa, the yielding strength sigma 0.2 is 1,400 to 1,950MPa, the wall thickness is 1 to 10 millimeters, the steel pipes are made of different materials, and the inside diameters of the steel pipes are conical or cylindrical; after expanding, the steel pipes are processed into the high-precision steel pipes, the roundness of which is less than or equal to 0.4 millimeter and the linearity of which is less than or equal to 0.6 millimeters per meter; and the method overcomes the defect that the normal temperature expanding process cannot meet the high-precision expanding requirements of the high-strength steel pipes. The method is suitable for expanding various high-strength steel pipes with different chemical components.The expanded high-strength steel pipes produced by using the method are widely applied in the fields of petroleum and natural gas delivery, aerospace and military affairs.

Description

technical field [0001] The invention relates to the field of thermal processing, in particular to a high-precision thermal diameter expansion method for high-strength steel pipes. Background technique [0002] The diameter expanding machine is mainly used for expanding the diameter, correcting the shape and relieving stress of the straight seam welded pipes for conveying oil and natural gas at room temperature. With the arrival of the construction climax of my country's east-west, north-south oil and gas trunk lines, submarine pipelines, and slurry pipelines, diameter expansion technology has been widely used as one of the important processes in the production of longitudinal welded pipes. However, with the improvement of steel pipe material grade and steel pipe thickness, especially in aerospace and military fields, σ b ≥1640MPa, σ 0.2 The diameter expansion of ultra-high-strength alloy steel pipes ≥ 1400MPa, the normal temperature expansion process can no longer meet the...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B21D39/20
Inventor 王振生王占理李书华李厚明王德清李显明陈佳蒙家才彭德平
Owner 湘潭华进重装科技股份有限公司
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