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Post-welding stress treatment method for carbon steel valve body

A stress treatment and valve body technology, applied in heat treatment furnaces, heat treatment equipment, furnaces, etc., can solve the problems of restricting the application environment of valves and inability to use, and achieve the effects of improving dispersion, eliminating coarse grains and improving inhomogeneity.

Inactive Publication Date: 2016-07-27
SUZHOU KEDI FLUID CONTROL EQUIP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] The carbon steel valve body is usually welded by castings. There will be internal stress between the welded casting and the welded body. The existence of internal stress will inevitably affect the internal toughness of the material in the welding hot zone, which limits the application environment of the valve. It cannot be used in an environment where the temperature is too high or too low

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0016] ① Post-weld heat treatment: Put the welded valve body in the furnace and heat it to 890°C and keep it warm for 1 hour. The furnace pressure is controlled at 1MPa. Take out the valve body and air cool to room temperature;

[0017] ②Secondary tempering: Put the cooled valve body into the furnace again and heat it to 300°C and keep it warm for 2 hours. The furnace pressure is controlled at 0.8MPa, and then the valve body is taken out and air-cooled to room temperature;

[0018] ③Performance heat treatment: Put the cooled valve body into the furnace again and heat it to 1100°C and keep it warm for 3 hours. The furnace pressure is controlled at 1.8MPa, and then the valve body is taken out and air-cooled to room temperature.

[0019] The mechanical properties of the valve body after the above method are as follows: tensile strength: 1642MPa;

Embodiment 2

[0021] ① Post-weld heat treatment: Put the welded valve body in the furnace and heat it to 900°C and keep it warm for 1.2 hours. The furnace pressure is controlled at 1.1MPa. Hours, take the valve body out and air cool to room temperature;

[0022] ②Secondary tempering: Put the cooled valve body into the furnace again and heat it to 310°C and keep it warm for 2.2 hours. The furnace pressure is controlled at 0.9MPa, and then the valve body is taken out and air-cooled to room temperature;

[0023] ③Performance heat treatment: Put the cooled valve body into the furnace again and heat it to 1120°C and keep it warm for 3.2 hours. The furnace pressure is controlled at 1.9MPa, and then the valve body is taken out and air-cooled to room temperature.

[0024] The mechanical properties of the valve body after the above method are as follows: tensile strength: 1706MPa;

Embodiment 3

[0026] ① Post-weld heat treatment: Put the welded valve body in the furnace and heat it to 910°C and keep it warm for 1.5 hours. The furnace pressure is controlled at 1.2MPa. Hours, take the valve body out and air cool to room temperature;

[0027] ②Secondary tempering: Put the cooled valve body into the furnace again and heat it to 320°C and keep it warm for 2.5 hours. The furnace pressure is controlled at 1MPa, and then the valve body is taken out and air-cooled to room temperature;

[0028] ③Performance heat treatment: Put the cooled valve body into the furnace again and heat it to 1150°C and keep it warm for 3.5 hours. The furnace pressure is controlled at 2MPa, and then the valve body is taken out and air-cooled to room temperature.

[0029] The mechanical properties of the valve body after the above method are as follows: tensile strength: 1687MPa;

[0030] The carbon steel valve body post-welding stress treatment method of the present invention carries out correspondin...

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Abstract

The invention discloses a post-welding stress treatment method for a carbon steel valve body. The post-welding stress treatment method comprises three steps that firstly, post-welding heat treatment is conducted, specifically, the welded valve body is heated to the temperature of 890-910 DEG C and subjected to heat preservation for 1-1.5 hours, then the valve body is cooled to the temperature of 700-720 DEG C and subjected to heat preservation for 1-1.5 hours, the valve body is cooled to the temperature of 500-510 DEG C and subjected to heat preservation for 0.5-1 hour, and the valve body is taken out and subjected to air cooling to the room temperature; secondly, secondary tempering is conducted, specifically, the cooled valve body is heated again to the temperature of 300-320 DEG C and subjected to heat preservation for 2-2.5 hours, and then the valve body is taken out and subjected to air cooling to the room temperature; and thirdly, performance heat treatment is conducted, specifically, the cooled valve body is heated again to the temperature of 1100-1150 DEG C and subjected to heat preservation for 3-3.5 hours, and then the valve body is taken out and subjected to air cooling to the room temperature. According to the post-welding stress treatment method for the valve body, corresponding heat treatment is conducted after welding, the form of alloy carbides of a carbon steel valve material is changed, the dispersity of the alloy carbides is improved, and nonuniformity of welding stress distribution is improved; the performance heat treatment is conducted after welding, and thus coarse grains are completely eliminated; the secondary tempering technique is adopted, and thus the effect that no quenched martensite structure exists in a basal body is guaranteed; and in this way, the treated carbon steel valve can be applied to the high-temperature environment and the low-temperature environment.

Description

technical field [0001] The invention relates to a stress treatment method, more precisely, a stress treatment method for a carbon steel valve body after welding. Background technique [0002] Carbon steel valve is a kind of gate valve system, but the material is different. The material is carbon steel, and the opening and closing part is a gate. The direction of movement of the gate is perpendicular to the direction of the fluid. regulation and throttling. The gate has two sealing surfaces. The two sealing surfaces of the most commonly used carbon steel valve form a wedge shape, and the wedge angle varies with the valve parameters. Among them, the gate of the wedge gate valve can be made into a whole, called a rigid gate. It can also be made into a gate that can produce a small amount of deformation to improve its manufacturability and compensate for the deviation of the sealing surface angle during processing. This kind of gate is called an elastic gate. [0003] The ca...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C21D9/50C21D1/18
CPCC21D9/50C21D1/18
Inventor 田洪卫
Owner SUZHOU KEDI FLUID CONTROL EQUIP
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