Stress corrosion dehiscence resistant ultrasonic impact treatment process

An ultrasonic impact and treatment technology, applied in heat treatment furnaces, heat treatment equipment, manufacturing tools, etc., can solve the problem of not using ultrasonic impact treatment technology, and achieve the effect of strengthening the resistance to stress corrosion cracking

Active Publication Date: 2009-07-29
NANJING UNIV OF TECH
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  • Summary
  • Abstract
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  • Claims
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AI Technical Summary

Problems solved by technology

[0004] At present, ultrasonic impact treatment has been applied at home and abroad to improve the fatigue performance of welded joints and the suppression of cold cracks, but in terms of improving the stress corrosion resistance of welded joints, ultrasonic impact treatment has not been used.

Method used

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  • Stress corrosion dehiscence resistant ultrasonic impact treatment process
  • Stress corrosion dehiscence resistant ultrasonic impact treatment process

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Embodiment 1

[0020] Refer to attached figure 1 and figure 2 , an ultrasonic impact treatment process for improving the stress corrosion cracking resistance of austenitic stainless steel welded joints, comprising the following steps:

[0021] 1. Perform surface treatment on the surface of the workpiece 4 to be treated, remove all dust, scale and coating on the surface 4 of the workpiece, and detect defects and cracks by using magnetic powder, dye penetration or ultrasonic waves.

[0022] 2. Aim the ultrasonic impact gun at the area to be treated. The area to be treated is the weld d1 and the heat-affected zone d2 on both sides of the weld. The width of the heat-affected zone d2 is 2 to 3 times the width of the weld d1, such as the width of the weld The width of the heat-affected zone on both sides of the weld is about 20-30mm. Then, the electrical energy is converted into mechanical energy by the transducer 1, and then the horn 2 is used to amplify the amplitude and push the needle 3 to ...

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Abstract

The invention relates to an ultrasonic impacting processing technique for resisting stress corrosion cracking, comprising steps of cleaning the surface of a workpiece to be processed to remove all the dust, scales and coating; aligning an ultrasonic impacting gun to the area to be processed including a welding line and heat-affected zones at the two sides of the welding line, wherein the width of the heat-affected zones is 2 to 3 times that of the welding line; converting electrical energy into mechanical energy by a transducer, wherein ultrasonic impacting frequency is 20kHz, leading the ultrasonic impacting gun vertical to the surface of the workpiece to be processed, using a pinhead to impact a determined welding line processing zone at a high speed, wherein coverage percentage of the impact is over 50%; using an X-ray diffractometer to detect the surface of the workpiece, wherein residual stress on the surface of the welded workpiece is compressive stress the value of which is far less than a threshold value causing stress corrosion cracking of the workpiece, and a solidified layer with certain thickness is formed on the surface of the workpiece, thus the processing is finished.

Description

technical field [0001] The ultrasonic impact treatment process of the invention relates to an ultrasonic impact treatment process for improving the resistance to stress corrosion cracking of welded joints. Background technique [0002] In petrochemical, textile, paper, atomic energy, pharmaceutical, space navigation, and marine development sectors that use stainless steel, stress corrosion cracking accidents near welded joints account for about 47% of wet corrosion damage accidents. A large number of research results show that the existence of welding residual tensile stress is one of the main factors leading to stress corrosion cracking of austenitic stainless steel welded joints. [0003] Ultrasonic impact treatment is an ideal method to eliminate welding residual tensile stress. The ultrasonic impact device is composed of an ultrasonic generator and an actuator. The ultrasonic generator converts the 50Hz power frequency alternating current on the power grid into an ultra...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C21D1/09C21D9/50
Inventor 凌祥马刚
Owner NANJING UNIV OF TECH
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