Induction Thermography with Automated Defect Detection in Comparison with Magnetic Particle Inspection

A study with in total 200 forged steel parts was performed in order to compare the testing reliability of automated inductive thermographic testing and magnetic particle inspection. A robot supported thermographic inspection station was used. The thermographic phase images obtained were analysed by an automatic defect detection procedure based on machine learning techniques. Results of magnetic particle inspection served as a reference. Depending on the type of test object, an agreement of 68% to 82% was achieved, if only the large indications of thermography were considered. Week thermographic indications turned out to be due to shallow cracks (<150 μm depth).