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Laser treatment method for raising stress corrosion resistance and abrasive resistance of nuclear power 690 alloy

A stress corrosion and laser treatment technology, applied in the field of laser treatment, can solve the problems of cracking, heat transfer tube stress corrosion, fretting wear, etc., and achieve the effect of uniform organization, effective absorption and dense structure

Active Publication Date: 2014-11-26
BEIJING UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] The purpose of the present invention is to solve the problems of stress corrosion cracking and fretting wear of heat transfer tubes, and provide a method for improving the stress corrosion resistance and wear resistance of nuclear power 690 alloy heat transfer tubes, which can make the heat transfer tubes resist stress corrosion The ability and wear resistance are greatly improved

Method used

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  • Laser treatment method for raising stress corrosion resistance and abrasive resistance of nuclear power 690 alloy
  • Laser treatment method for raising stress corrosion resistance and abrasive resistance of nuclear power 690 alloy
  • Laser treatment method for raising stress corrosion resistance and abrasive resistance of nuclear power 690 alloy

Examples

Experimental program
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Effect test

Embodiment 1

[0028] The laser melting and nitriding process is as follows: select an Inconel690 alloy heat transfer tube (outer diameter is 19 mm, wall thickness is 1.2 mm, length 300 mm), the outer surface 1 of the heat transfer tube is cleaned with alcohol to remove surface impurities, and the heat transfer tube The tube is fixed on the turntable 2 of the machine tool, and the rotation speed of the turntable is set so that the rotation speed of the outer circle of the 690 alloy heat transfer tube reaches 200mm / min. At the same time, a fiber laser with a wavelength of 1070nm is used for surface treatment, and 3 laser heat sources are used for the 690 alloy heat transfer tube. The surface is fused, the laser output power is 300W, the spot diameter after focusing is 0.5mm, and the scanning overlap rate is 20%. The inlet and outlet pressure is 0.5MPa high-purity nitrogen (99.995%), the distance between the nitriding nozzle and the surface of the heat transfer tube is 12mm, and the argon nozzl...

Embodiment 2

[0043] The laser melting and nitriding process is as follows: the pretreatment of melting and nitriding is the same as that in Example 1, and the semiconductor laser with a wavelength of 980nm is used for surface treatment, the output power of the semiconductor laser is 600W, and the linear speed of the outer circle of the heat transfer tube is 500mm / min , the spot diameter is 1.5mm, and the scanning overlap rate is 40%. The nitriding nozzle fixed on the periphery of the laser system sends 25L / min high-purity nitrogen gas (99.995%) to the laser irradiation area. The distance between the nozzle and the surface of the heat transfer tube is The distance is 9mm, the nitrogen outlet pressure is 0.75MPa, and at the same time, 25L / min pure argon (99.95%) is passed into the heat transfer tube through the argon nozzle connected to the inner wall of the heat transfer tube for protection and cooling.

[0044] Part of the sample was cut off, and the average thickness of the fused nitriding...

Embodiment 3

[0050]The laser melting and nitriding process is as follows: the pretreatment of the melting and nitriding is the same as that in Example 1, using a semiconductor laser with a wavelength of 800nm ​​for surface treatment, the laser output power is 1000W, and the outer circle speed of the heat transfer tube is 800mm / min. The diameter of the spot is 3mm, and the scanning overlap rate is 60%. The nozzle fixed on the periphery of the laser system sends 30L / min high-purity nitrogen (99.995%) to the laser irradiation area. The distance between the nozzle and the surface of the heat transfer tube is 5mm. The outlet pressure is 1MPa, and at the same time, 30L / min pure argon (99.95%) is fed into the heat transfer tube through the argon nozzle connected to the inner wall of the heat transfer tube for protection and cooling.

[0051] Part of the sample was cut off, and the thickness of the fused nitriding layer was measured to be about 100 μm by microscope observation, and the hardness of ...

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Abstract

The invention relates to a laser treatment method for raising stress corrosion resistance and abrasive resistance of nuclear power 690 alloy. According to the invention, a continuous laser thermal source with the wavelength of 800-1070nm is adopted to carry out a melting treatment on the cylindrical surface of a 690 alloy heat-transfer pipe while a nitrogen-assisted nitriding treatment is carried out. Laser power is 300-1000 W; laser scanning linear velocity is 200-800 mm / min; spot diameter is 0.5-3 mm; and overlap rate is 20-60%. When the nitrogen-assisted nitriding treatment is carried out while laser melting of the cylindrical surface of the 690 alloy pipe, flow rate of nitrogen is 20-30L / min; the distance from a nitrogen nozzle to the surface of the heat-transfer pipe is 5-12 mm; nitrogen pressure at an nozzle outlet is 0.5-1 MPa; and argon with auxiliary flow rate of 20-30L / min in a bore of the 690 heat-transfer pipe is used to protect the surface of the bore and cool the pipe wall. Laser melting is adopted and nitrogen is blown to a melting zone to carry out the nitriding treatment on the surface of the 690 alloy heat-transfer pipe. Thus, a compact nitriding layer with the thickness of 20-100 microns is obtained, so as to raise stress corrosion resistance and abrasive resistance.

Description

technical field [0001] The invention relates to a laser treatment method for improving the stress corrosion resistance and wear resistance of nuclear power 690 alloy, belonging to the field of laser material processing. Background technique [0002] Compared with traditional thermal power, hydropower and other energy systems, nuclear power, as a safe, clean and economical new energy, plays an irreplaceable role in the energy supply of human beings. The area of ​​the heat transfer tube of the steam generator in the pressurized water reactor nuclear power plant accounts for about 80% of the area of ​​the pressure-bearing boundary of the primary circuit. Experience shows that about 30% to 40% of pressurized water reactors affect normal operation, reduce power operation or are forced to shut down due to steam generator heat transfer tube damage. The damage of heat transfer tubes is caused by various types of corrosion, including pitting corrosion (Pitting), intergranular corros...

Claims

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Application Information

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IPC IPC(8): C21D1/09C23C8/26C23F17/00
Inventor 杨胶溪李子阳文强肖志勇
Owner BEIJING UNIV OF TECH
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