Eddy Current Thermography as a Tool for Detecting the Location and Dimension of Edge Defects in Cr–Mo Steel Plate

Abstract

The present study discusses the potential of eddy current thermography in the detection of edge defects in metal plates. The focus is on detecting the defect’s dimension and location for the defects available at the edge of metal plates. We have used a slab of SA387 GR12 (Killed steel) for performing our study. SA387 GR12 (Killed steel) possesses tremendous tensile and yield strength. The combination of chromium-molybdenum provides corrosion-combating skills along with improved tensile strength at higher temperatures. It has wide applications in the field of power (especially thermal power plants), oil and chemical industry, construction sector etc. as heat exchangers, pressure vessels, industrial boilers, piping industry and in piping support structures, sour service environments etc. Small cracks in any component can cause catastrophic failures. So it becomes a necessity to detect the crack in the initial stage itself, especially to avoid stress concentration in processes like rolling of steel plates. The study is performed on a SA387 GR12 sample with defects created at various angles. Similar cracks can also be found in rails, created because of rolled contact fatigue. Hence the study is going to be useful for the detection of defects in rails also. ECT offers further possibilities in the area of automation and has various advantages in comparison to conventional methods and the same is also discussed in the work.