Ultrasonic flaw detection method

By focusing and deflecting ultrasonic waves in the axial direction of welded steel pipes, the method enhances defect detection sensitivity and reduces noise interference, effectively identifying minute flaws around the weld area.

JP7868475B2Active Publication Date: 2026-06-02JFE STEEL CORP
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Patent Information

Authority / Receiving Office
JP · JP
Patent Type
Patents
Current Assignee / Owner
JFE STEEL CORP
Filing Date
2022-10-06
Publication Date
2026-06-02

AI Technical Summary

Technical Problem

Existing ultrasonic flaw detection methods struggle to detect minute defects such as hook cracks and external cutting defects around the weld area of welded steel pipes with high sensitivity and over a wide area, particularly in small-diameter, thin-walled steel pipes, due to reflection loss, increased noise, and false echoes from bead cutting steps.

Method used

The method involves using ultrasonic probes arranged in the circumferential direction of the pipe, transmitting waves to reflect once or more on the pipe surfaces, focusing them in the axial direction, and deflecting them at an angle θ1 to enhance signal-to-noise ratio, while performing electronic scanning in the circumferential direction, using matrix or linear phased array probes with acoustic lenses to optimize focusing and reduce noise interference.

Benefits of technology

This approach enables high-sensitivity detection of defects over a wide area around the welded joint, including the heat-affected zone and bead cutting area, by improving the signal-to-noise ratio and reducing false echoes, allowing for accurate identification of minute flaws like hook cracks and internal bead steps.

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Abstract

To provide an ultrasonic flaw detection method which enables high-sensitivity detection of minute scratches such as hook cracks and external surface cutting scratches near welds of welded steel pipes over a wide range, which was previously difficult, in addition to detection of cracks and inclusions in weld lines.SOLUTION: An ultrasonic flaw detection method is provided, comprising transmitting ultrasonic waves using ultrasonic probes juxtaposed in a circumferential direction of a steel pipe in such as way that the ultrasonic waves are reflected at least once by an inner surface or outer surface of the steel pipe, focusing the ultrasonic waves in an axial direction of the steel pipe at a flaw detection point inside the steel pipe, and deflecting the ultrasonic waves in the axial direction to (electronically) scan the steel pipe in the circumferential direction.SELECTED DRAWING: Figure 1
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