Eliminating method for tempered seamless steel pipe residual stress and adopted bi-directional chain type cooling bed

A technology of seamless steel pipe and residual stress, applied in the field of heat treatment, can solve the problems of increased oxide scale on the surface of steel pipe, rising cost, occupation of quenching and tempering capacity, etc.

Pending Publication Date: 2018-08-14
DAYE SPECIAL STEEL CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

According to the requirements of API5C3 and related technical standards of users, the lower the straightening temperature, the greater the residual stress of the steel pipe. Generally, the steel pipe of L80-Q125 steel grade should be straightened by hot roller after quenching and tempering. The temperature of the steel pipe after straightening should be above 510 °C , if the straightening temperature of the steel pipe is lower than 510°C, the residual st...

Method used

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  • Eliminating method for tempered seamless steel pipe residual stress and adopted bi-directional chain type cooling bed
  • Eliminating method for tempered seamless steel pipe residual stress and adopted bi-directional chain type cooling bed
  • Eliminating method for tempered seamless steel pipe residual stress and adopted bi-directional chain type cooling bed

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Experimental program
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Effect test

Embodiment 1

[0055] This embodiment provides a method for eliminating the residual stress of quenched and tempered seamless steel pipe 5, the process steps of the elimination method are as follows:

[0056] (1) The seamless steel pipe 5 whose steel type is 42CrMo and whose specification is 323.9*50.8mm is rolled by a six-roller straightening machine after hot rolling, and the bending degree of the seamless steel pipe 5 after straightening is 1.39mm / m;

[0057] (2) For quenching, use a walking heating furnace for quenching and heating. The quenching heating temperature is 840°C and the holding time is 145 minutes. , when the steel pipe is cooled to 95°C, the cooling water is stopped, and then tempered with a stepping furnace for tempering heating, the heating temperature is 560°C, and the holding time is 345 minutes;

[0058] (3) After the seamless steel pipe 5 leaves the tempering furnace, the seamless steel pipe 5 is placed on the two-way chain cooling bed through the conveying roller tab...

Embodiment 2

[0061] (1) The steel grade is ASTM A519 4140 and the specification is 127*12.7mm seamless steel pipe 5. After hot rolling, a six-roller straightener is used for roll straightening. After straightening, the seamless steel pipe 5 has a curvature of 1.75mm / m;

[0062] (2) The steel pipe is quenched and heated in a progressive heating furnace. The heating temperature is 835°C and the holding time is 25 minutes. When cooling to 128°C, stop the cooling water, then step into the furnace for tempering and heating, the heating temperature is 615°C, and the tempering holding time is 59 minutes;

[0063] (3) After the steel pipe comes out of the tempering furnace, the seamless steel pipe 5 is placed on the two-way chain cooling bed through the conveying roller table 1 and the pulling device 2. The slope of the chain bed is 3°, the front is low and the back is high, and the forward chain 6 has 3, driven by a forward chain drive motor 3, 3 reverse chains 7, driven by a reverse chain drive ...

Embodiment 3

[0066] (1) The steel grade is ASTM A519 4130, the specification is 215.9*38.1mm seamless steel pipe 5, and after hot rolling, a six-roller straightening machine is used for roll straightening, and the bending degree of the seamless steel pipe 5 after straightening is 1.62mm / m;

[0067] (2) The steel pipe is quenched and heated in a progressive heating furnace. The heating temperature is 885°C and the holding time is 62 minutes. When cooling to 105°C, stop the cooling water, and then step into the furnace for tempering and heating. The heating temperature is 710°C, and the tempering holding time is 135 minutes;

[0068] (3) After the steel pipe comes out of the tempering furnace, the seamless steel pipe 5 is placed on the two-way chain cooling bed through the conveying roller table 1 and the pulling device 2. The slope of the chain bed is 3°, the front is low and the back is high, and the forward chain 6 has 3, driven by a forward chain drive motor 3, 3 reverse chains 7, driven...

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Abstract

The invention provides an eliminating method for tempered seamless steel pipe residual stress and an adopted bi-directional chain type cooling bed. A straightening working procedure is adopted beforetempering, and the straightness accuracy of a steel pipe before tempering is ensured; the bi-directional chain type cooling bed with the gradient is adopted, the steel pipe is constantly rotated in the cooling process after being tempered, the straightness accuracy of the steel pipe in the cooling process after tempering is ensured, and therefore it is ensured that the steel pipe is not subjectedto stress relief annealing after being tempered and residual stress does not exceed 3% of the specified minimum yield strength while the straightness accuracy reaches 1 mm/m or below. The gradient ofa bed boy of the bi-directional chain type cooling bed is 2-5 degrees, the bed body is provided with the lower front portion and the higher rear portion and formed by alternately arranging multiple forward chains and multiple reverse chains at intervals, the forward direction of the forward chains is the same as the movement direction of the seamless steel pipe, and the forward direction of the reverse chains is opposite to the movement direction of the seamless steel pipe. By means of the eliminating method, the technical effect of achieving straightness and low residual stress simultaneouslyis achieved, the working procedure of stress relief annealing is omitted, the production cost is reduced, and the surface quality of the steel pipe is improved.

Description

technical field [0001] The invention belongs to the technical field of heat treatment, and in particular relates to a method for eliminating the residual stress of a quenched and tempered seamless steel pipe and a two-way chain cooling bed used for eliminating the residual stress of the quenched and tempered seamless steel pipe. Background technique [0002] Residual stress will reduce the fatigue strength of the material, affect the collapse strength, increase the stress corrosion of the pipe body, and at the same time, there will be processing deformation during material processing. Therefore, in the fields of construction machinery, automobiles, oil and gas exploration, the residual stress of seamless steel pipes is generally The requirement shall not exceed ±5% of the specified minimum yield strength for the material. [0003] After quenching and tempering, the straightness of the seamless steel pipe must be guaranteed, and usually it will be straightened after quenching...

Claims

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Application Information

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IPC IPC(8): C21D9/08C21D1/18C21D1/667B21D3/02
CPCC21D1/18C21D1/667C21D9/08B21D3/02Y02P10/20
Inventor 潘先明万五霞黎福华唐科姚火能彭俊杨煌光李倩
Owner DAYE SPECIAL STEEL CO LTD
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