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On-line quenching preparation method for reducing residual stress of hot-rolled seamless steel tube and steel tube

A seamless steel pipe and residual stress technology, applied in quenching devices, heat treatment equipment, heat treatment furnaces, etc., can solve problems such as inconsistency of online quenching process, avoid quenching cracks, facilitate implementation, and reduce residual stress levels.

Active Publication Date: 2021-08-13
BAOSHAN IRON & STEEL CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0010] Another example is JP2000219914A, which discloses a fine-grained steel pipe, which also achieves grain refinement through an on-line normalization process, which is also inconsistent with the on-line quenching process involved in the present invention.

Method used

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  • On-line quenching preparation method for reducing residual stress of hot-rolled seamless steel tube and steel tube

Examples

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preparation example Construction

[0034] The preparation method of the present invention comprises the following specific steps:

[0035] 1) Directly cast the smelted molten steel into a tube billet, or first cast and then forge the billet forging (or rolling) into a tube billet, then heat the tube billet, and roll the tube billet into a steel pipe according to the existing hot rolling method;

[0036] 2) After the steel pipe rolling is completed, the steel pipe needs to be quenched online when the Ar3 temperature of the steel is between 30°C and 1100°C;

[0037] 3) On-line quenching and cooling process:

[0038] 3.1) Cool by spraying water evenly around the outer wall of the steel pipe, and the water pressure is controlled between 0.2MPa and 5MPa;

[0039] 3.2) When the surface temperature of the steel pipe has not yet dropped to the Ms point temperature, spray water on the inner wall of the steel pipe so that the water filling amount of the inner cavity of the steel pipe needs to exceed 1 / 4 of the inner cav...

Embodiment 1

[0052] Specific steps are as follows:

[0053] 1) Cast an alloy of grade 16Mn (0.17%C-1.65%Mn) into an ingot, and forge the ingot into a tube blank of φ244.5*10.05, heat the tube blank to 1250°C and keep it for 2 hours, and then perforate it , hot rolling, sizing and other general hot-rolled seamless steel pipe production processes to make seamless steel pipes;

[0054] 2) After the steel pipe rolling is completed, the surface temperature of the steel pipe is measured to be 930°C, which is 30°C higher than the Ar3 temperature (835°C) of the steel, and online quenching is carried out;

[0055] 3) On-line quenching and cooling process:

[0056] 3.1) Cool by spraying water evenly around the outer wall of the steel pipe, and the water pressure is controlled at 0.55MPa;

[0057] 3.2) When the surface temperature of the steel pipe has not yet dropped to the Ms point temperature of 410°C (this value can be obtained by consulting relevant literature, or can be measured by thermal si...

Embodiment 2

[0061] Specific steps are as follows:

[0062] 1) Cast the alloy of grade 20Mn2 (0.2%C-1.6%Mn) into an ingot, and forge the ingot into a tube blank of φ244.5*10.05, heat the tube blank to 1250°C and keep it for 2 hours, and then perforate it , hot rolling, sizing and other general hot-rolled seamless steel pipe production processes to make seamless steel pipes;

[0063] 2) After the steel pipe rolling is completed, the surface temperature of the steel pipe is measured to be 920°C, which is 740°C higher than the Ar3 temperature of the steel, and online quenching is carried out;

[0064] 3) On-line quenching and cooling process:

[0065] 3.1) Cool by spraying water evenly around the outer wall of the steel pipe, and the water pressure is controlled at 0.45MPa;

[0066] 3.2) When the surface temperature of the steel pipe has not yet dropped to the Ms point temperature of 400°C, spray water on the inner wall of the steel pipe so that the water filling amount of the inner cavity ...

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Abstract

The invention discloses an on-line quenching preparation method for reducing residual stress of a hot-rolled seamless steel tube and the steel tube. The preparation method comprises the following steps that 1, a tube blank is rolled into the steel tube in an existing hot rolling manner; 2, when the temperature of the steel tube is not lower than the Ar3 temperature of steel, cooling is conducted in the mode that water is evenly sprayed to the outer wall of the steel tube in the circumferential direction; 3, when the surface temperature of the steel tube is not reduced to the Ms point temperature, water is sprayed to the inner wall of the steel tube; and 4, when the surface temperature of the steel tube is reduced to 200 DEG C or below, water spraying is stopped, cooling is carried out, and finally the steel tube is converted into air cooling. The on-line quenching preparation method can effectively reduce the residual stress level of the seamless steel tube after quenching, and prevents the seamless steel tube from quenching cracking.

Description

technical field [0001] The invention relates to a production process method of a hot-rolled seamless steel pipe, more specifically, an on-line quenching preparation method for reducing the residual stress of a hot-rolled seamless steel pipe and the steel pipe thereof. Background technique [0002] Due to the limitation of product shape and manufacturing method, hot-rolled seamless steel pipe can only rely on adding alloy elements and off-line heat treatment after rolling to improve product performance for a long time. Taking oil well pipes as an example, grades above 555MPa (80Ksi) need to be produced by adding more alloying elements (such as microalloying to produce N80-1) or off-line transfer to treatment (N80-Q, P110, etc.), which significantly increases the manufacturing cost. cost. [0003] At present, the usual production process of hot-rolled seamless steel pipes is to first enter the pipe warehouse after rolling, and then perform heat treatment according to needs. T...

Claims

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Application Information

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IPC IPC(8): C21D9/08C21D1/667C21D8/10
CPCC21D9/085C21D1/667C21D8/105Y02P10/20
Inventor 储双杰刘耀恒张忠铧罗明孙文
Owner BAOSHAN IRON & STEEL CO LTD
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