• CN: 11-2187/TH
  • ISSN: 0577-6686

Journal of Mechanical Engineering ›› 2025, Vol. 61 ›› Issue (4): 24-31.doi: 10.3901/JME.2025.04.024

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Multi-resolution Low-frequency Ultrasonic C-scan Quantitative Detection of Micron-level Defects in 3D Printed Nickel Base Alloy

MA Zhiyuan1, CUI Zhen1, KANG Da2, LIU Xiaoqing1, LIN Li1   

  1. 1. NDT & E Laboratory, Dalian University of Technology, Dalian 116024;
    2. Beijing Power Machinery Institute, Beijing 100074
  • Received:2024-02-07 Revised:2024-08-12 Published:2025-04-14

Abstract: Ultrasonic C-scan technology is widely used in the automatic detection of defects such as sub-millimeter pores, cracks, and incomplete fusion in 3D printed alloy components. It is difficult to improve the resolution and quantitative accuracy under a large detection depth. A split spectrum processing technology for C-scan detection of water immersion point focusing probe is developed. A new method of quantitative detection of sub-millimeter defects by multi-resolution low-frequency ultrasonic C-scan is proposed by developing the crack spectrum processing technology of water immersion focusing probe C-scan detection, which realizes the comprehensive improvement of detection depth, resolution and quantitative accuracy of micron-scale defects in alloy components. Ultrasonic C-scan system combined with a 20 MHz water immersion point focusing probe is used for the experiment. The multi-resolution ability of the focusing probe is measured by a right-angle gap sample. The 3D printed nickel-based superalloy containing pore-type defects with a diameter of φ100~800 μm is used to verify the effectiveness of the proposed defect quantification method. Results indicate that the multi-resolution ultrasonic C-scan can improve the lateral resolution from 210 μm to less than 118 μm at the focus, and the relative error of the φ200 μm defect is increased from 105% to 8%. The proposed method can also increase the length of the focal beam by nearly three times, which significantly improves the resolution of the far focal position.

Key words: ultrasonic C-scan, split spectrum processing, nickel-based alloy, sub-millimeter defects, lateral resolution

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