Liquid nitrogen cooling in IR thermography applied to steel specimen

L. Lei; G. Ferrarini; A. Bortolin; G. Cadelano; P. Bison; X. Maldague

doi:10.1117/12.2262208

5 May 2017 Liquid nitrogen cooling in IR thermography applied to steel specimen

L. Lei, G. Ferrarini, A. Bortolin, G. Cadelano, P. Bison, X. Maldague

Proceedings Volume 10214, Thermosense: Thermal Infrared Applications XXXIX; 102140T (2017) https://doi.org/10.1117/12.2262208
Event: SPIE Commercial + Scientific Sensing and Imaging, 2017, Anaheim, CA, United States

Abstract

Pulsed Thermography (PT) is one of the most common methods in Active Thermography procedures of the Thermography for NDT & E (Nondestructive Testing & Evaluation), due to the rapidity and convenience of this inspection technique. Flashes or lamps are often used to heat the samples in the traditional PT. This paper mainly explores exactly the opposite external stimulation in IR Thermography: cooling instead of heating. A steel sample with flat-bottom holes of different depths and sizes has been tested. Liquid nitrogen (LN₂) is sprinkled on the surface of the specimen and the whole process is captured by a thermal camera. To obtain a good comparison, two other classic NDT techniques, Pulsed Thermography and Lock-In Thermography, are also employed. In particular, the Lock-in method is implemented with three different frequencies. In the image processing procedure, the Principal Component Thermography (PCT) method has been performed on all thermal images. For Lock-In results, both Phase and Amplitude images are generated by Fast Fourier Transform (FFT). Results show that all techniques presented part of the defects while the LN₂ technique displays the flaws only at the beginning of the test. Moreover, a binary threshold post-processing is applied to the thermal images, and by comparing these images to a binary map of the location of the defects, the corresponding Receiver Operating Characteristic (ROC) curves are established and discussed. A comparison of the results indicates that the better ROC curve is obtained using the Flash technique with PCT processing method.

Conference Presentation

Citation Download Citation

L. Lei, G. Ferrarini, A. Bortolin, G. Cadelano, P. Bison, and X. Maldague "Liquid nitrogen cooling in IR thermography applied to steel specimen", Proc. SPIE 10214, Thermosense: Thermal Infrared Applications XXXIX, 102140T (5 May 2017); https://doi.org/10.1117/12.2262208

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available