Applying pulse thermography technique for corrosion defect evaluation on the steel plates

Pulse thermography is used in various industries to inspect and monitor certain parts and assemblies. Corrosion in steel structures and components is one of the most important defects that impose huge costs on industries each year, which can be partially reduced by timely detection. There are many ways to diagnose corrosion, but the high speed of testing, the need to not sample, the inspection of large surfaces in low time, and the ability to perform it on many materials, are the advantages of pulse thermography. In this paper, from non-destructive testing methods, pulsed thermography is used to detect corrosion defects in metal sheets. The samples tested in this paper are made of low carbon steel and alloy steel which have many applications in various industries. The aim of this study was to simulate and identify corrosion defects in steel parts. Various defects were designed and fabricated to evaluate the strength of this non-destructive testing in determining the minimum diameter and maximum depth. The effects of excitation sources distance, radiation angle, material of samples and duration of excitation on the tests were investigated. The ability to detect defects without the need for image processing has been exploited to the advantage of the employed method. From the pattern of defects created in the samples, the smallest detected defect in the low carbon steel specimen was 4 mm in diameter at 1 mm depth and in the alloy steel specimen the smallest detected defect was 3 mm in diameter at 1 mm depth.