Stress corrosion dehiscence resistant ultrasonic impact treatment process

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...

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.

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