鋼板夾層或介在物之超音波頻率響應特性研究

A Study for the Characteristic of Ultrasound Frequency Response in Laminations or Inclusions of Steel Plates

鄭錦智(Jin-Jhy Jeng)

《石油季刊》 43卷3期 (2007/09) Pp. 75-86

https://doi.org/10.30128/JP.200709.0007

摘要

鋼板在製造中常伴隨著夾層或介在物的發生，而此現象亦會造成測厚值減少，而使得誤判為減薄超過可接受厚度的情形，進而汰換該設備或緊急停爐而造成生產損失，對事業單位而言影響非常之大。由於目前CNS規範之超音波直束檢測技術僅針對新製材料之夾層檢測，且在實務上當利用超音波直束法在使用中材料之夾層、扁平狀介在物的判斷上容易與腐蝕減薄訊號混淆，而致使檢測人員很難區分屬於夾層（介在物）或腐蝕減薄，因此實務上亟需一套鑑別的方法用來鑑別使用中材料之腐蝕減薄及夾層或介在物的現象。
本研究利用超音波寬頻探頭激發寬頻超音波，依背面回波及指示回波之頻率響應來探討夾層及非金屬介在物之超音波頻率響應特性，以做為未來建立鑑別夾層或是腐蝕減薄技術之基礎。本研究針對具有夾層或非金屬介在物的自然缺陷進行試驗，並歸納出其結果為：當有夾層或介在物之回波與背面回波同時存在時，則夾層或介在物回波在高頻之響應會比背面回波來得大；當僅有夾層或介在物回波時則夾層回波與健全區背面回波之頻率響應相似。除此之外，有夾層或介在物存在之頻率響應與健全部之頻率響應會有明顯的不同。

關鍵字

非金屬介在物 ； 夾層 ； 超音波直束法 ； 頻率響應

並列摘要

The production of steel plate is usually accompanied by the occurrence of lamination or inclusion, and this phenomenon will result in the reducing of thickness measurement, misleading that material thinning exceeds the acceptable thickness and therefore influencing the enterprises very much for replacement of that equipment or production losses due to emergency shut-down. Because the current technique of Method of Straight-Beam Ultrasonic Test provided by CNS is only aimed at lamination test of newly-made materials; moreover, in practice, the ultrasonic signals of corrosive thinning can easily confused with the one of the lamination, or flat type inclusion, in used materials for Straight-Beam Ultrasonic Test, making it hard for inspectors to tell from lamination (inclusion) or corrosive thinning. Therefore, in practice, a set of appraisal methods is urgently needed to distinguish between corrosive thinning and phenomena of lamination, or inclusion, of materials in use.
This study uses ultrasound broad-band probe to induce broad-band ultrasound and to make sure whether it is corrosive thinning or lamination by the frequency response of the back echo and indicative echo to establish the basic data of distinguishing lamination from corrosive thinning in future. In this study, we aimed at natural defects with lamination and non-metal inclusion to conduct the tests and the results are concluded as follows: When the lamination echo, or inclusion echo, and the back echo both exist, the response of lamination echo in high frequency is greater than the back echo; when there exists only the lamination echo, or inclusion echo, the frequency response of lamination echo is similar to that of back echo in sound area. Other wise, the frequency response is different between the lamination area, or inclusion, and soundness area.

並列關鍵字

Non-Metal Inclusion ； Lamination ； Method of Straight-Beam Ultrasonic Test ； Frequency Response