Generator bridging strand brazing ultrasonic detection method

Abstract

The invention relates to a generator bridging strand brazing ultrasonic detection method. The technical scheme is that the method further comprises an ultrasonic detector and two ultrasonic longitudinal wave transducers connected with the ultrasonic detector, the transmitting transducer is used for transmitting pulse ultrasonic waves to a detected object, the pulse ultrasonic waves transmitted bythe transmitting transducer penetrate through the detected object and then are received by the receiving transducer, and whether the detected object has defects or not and the severity degree of the defects are judged according to the intensity of received ultrasonic signals. The method is simple, and the acoustic beams are only propagated unidirectionally, so that reduction of sound path attenuation is small, the method has no detection blind area and is suitable for detecting high-attenuation materials. In addition, the shielding effect of defects is not affected by factors such as defect roughness or defect orientation, the method is suitable for detecting the defects in the brazed layer of the bridging strand of the generator of a thermal power plant, and is high in detection speed andaccuracy, thereby being an innovation on the generator bridging strand brazing ultrasonic detection method.

Description

technical field [0001] The invention belongs to the technical field of non-destructive testing, and in particular relates to an ultrasonic detection method for defects in the brazing layer of a water box cover of a hydropower joint of a generator and a bridging strand as well as a bridging strand and an L-shaped pressure plate, which is suitable for bridging a generator in a thermal power plant Strand welding quality inspection. Background technique [0002] The welding between the generator water box cover of the thermal power plant and the jumper strands, and the welding between the jumper strands and the L-shaped pressure plate adopts medium-frequency induction brazing. The main component of the welding material is tin, and the welding temperature is 200 ° C. The connection point, the path of the current, if a welding defect occurs here, although it does not involve water or hydrogen leakage, it will cause the resistance value to change. For a defect with a small area, th...

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Problems solved by technology

[0003] The generator water box cover, the jumper strands and the L-shaped pressure plate are all made of copper, with large differences in grain size, and the main component of the welding material is tin, which belongs to dissimilar steel welding. When the straight probe ultrasonic reflection method is used for testing, The sound beam attenuation is large, the bottom echo is low or completely disappears, and the signal-to-noise ratio is low, the penetration ability is reduced, and the detection sensitivity cannot be guaranteed

However, the internal defects of the brazing layer cannot be found by the penetration detection method, resulting in missed detection of defects, and the penetration detection operation is intensive and the detection efficiency is low

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