Correction Coefficient of Loop Coupling Compensation for Circumferential Butt Welded Joints in Thermal Power Plant
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摘要: 为了解决火电厂环向对接接头超声检测时因工件曲率引起灵敏度损失的问题，对平面探头与曲面工件的接触情况进行了理论分析，并利用CSK-ⅡA试块与不同曲率和厚度的RB-C试块进行了灵敏度对比试验。结果表明：探头的频率、K值、晶片尺寸、耦合剂类型和工件的曲率半径均会影响超声检测灵敏度，且探头的晶片尺寸和工件的曲率半径是最主要的影响因素。曲面工件由于减小了与探头接触的有效面积，从而降低了缺陷回波声压透射率，引起了工件检测灵敏度的损失。通过试验研究得出了10种火电厂环向对接接头超声检测常用规格的RB-C试块的曲面耦合补偿修正系数。Abstract: In order to solve the problem of sensitivity loss due to the curvature of workpieces during the ultrasonic testing of circumferential butt welded joints in thermal power plant, the contact state between plane probe and curved workpiece is theoretically analyzed. The sensitivity contrast test was performed for the CSK-Ⅱ A test block and RB-C test block with different curvature and thickness. The results show that the probe's frequency, k value, wafer size, the type of coupling agent and the radius of curvature of the workpiece all affect the sensitivity of ultrasonic testing. The wafer size of the probe and the radius of curvature of the workpiece are the most important factors. The curvature workpieces reduce the effective area of contact with the probe, thus reducing the transmissivity of the defect echo sound pressure and leading to the loss of sensitivity of the workpiece inspection. In this paper, the correction coefficient of the surface coupling compensation of RB-C test block, which is commonly used in the ultrasonic testing of the circumferential butt welded joints of thermal power plant, is obtained through experimental research.
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Keywords:
- ultrasonic testing /
- DAC curve /
- surface coupling compensation /
- RB-C test block
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