Method for phased array ultrasonic detection of gradient sound velocity non-uniform metal thick plate weld joint

Abstract

The invention discloses a method for phased array ultrasonic detection of a gradient sound velocity non-uniform metal thick plate weld joint, and the methid comprises the following steps that S1, a calibration test block is prepared, and a plurality of transverse through holes with different depths are formed in the calibration test block; S2, type selection of the angle probe is performed; S3, the transverse through holes with different physical depths Dp on a single calibration test block are scanned in a fan shape by using a phased array ultrasonic technology, and the angles from the incident points of the corresponding angle probes to the transverse through holes and the sound path Sr data are obtained; S4, polynomial fitting is performed on the data to obtain a mapping relation function; S5, whether the mapping relation function is reasonable or not is verified through the verification test block, and whether the verification test block is applicable to the method or not is judged; and S6, the weld joint of the metal thick plate with non-uniform sound velocity is scanned by using a phased array ultrasonic technology. When the method is actually used for detecting the gradientsound velocity non-uniform metal thick plate weld joint, the corresponding physical depth can be inversely checked through the mapping relation function, and the depth error for detecting the non-uniform material defects through the phased array ultrasonic detection technology is reduced.

Description

technical field [0001] The invention belongs to the technical field of material measurement, relates to ultrasonic detection of welds, in particular to a phased array ultrasonic detection method for welds of non-uniform metal thick plates with gradually changing sound velocity. Background technique [0002] With the continuous development of the shipping industry, the cargo capacity of large container ships is also increasing. From the earlier 8000TEU container ships to the current 20000TEU container ships, the rapid development of large container ships has benefited from the rapid development of hull materials. At present, the steel of important structures such as decks and outer plates of container ships exceeding 18,000 TEU is made of specially treated rolled steel. After testing, it is known that it is a steel type with a non-uniform sound beam, and its welded structure There is a problem of poor detection accuracy. [0003] TMCP steel is a kind of steel processed by us...

AI Technical Summary

Problems solved by technology

[0006] At present, the commonly used detection methods have obvious disadvantages: First, the on-site detection process requires the use of IIW test blocks to measure the sound velocity of materials. This calibration method is generally used for isotropic and uniform sound velocity materials. In the process of internal propagation, affected by various factors, the propagation path may be curved, and the true propagation speed in different depth ranges is also inconsistent. Therefore, the method of calibrating uniform materials is used to detect non-uniform materials, and its positioning is especially The positioning in the depth direction will cause a huge error

[0007] Secondly, for thicker steel, the propagation distance of the two waves is greater, and the ultrasonic propagation energy is significantly reduced. For conventional ultrasonic testing technology, the sensitivity of receiving defect echoes is greatly reduced, and the detection object is non-uniform Material and internal crystal grains cause refraction of sound waves, which may cause small defect echoes and clutter to interfere with each other when detecting large-thickness welds, which will have a greater impact on the determination of the actual position of the defect

For steel welds with small thickness, the consequences can be ignored, but TMCP steel is mostly used in large container ships, and the thickness of the plates used is above 40mm. The reliability of the detection is questioned

[0008] At present, there is no public report at home and abroad that can completely solve the sound beam measurement and detection calibration method for welds of thick-walled metal materials with inhomogeneous materials, and professionals from all walks of life are also working hard to find a solution

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