Non-Destructive Testing of the Welded Joints Using Infrared Thermography Technique

One of the most important and challenging processes of manufacturing industrial parts has always been the process of creating various joints, including permanent joints by welding method. Considering the sensitivity of the welded joints in terms of defects and cracks caused by the process, checking the accuracy, precision and health of the created weld is one of the most important concerns of researchers and craftsmen. For this reason, the development of non-destructive methods to check the integrity and quality of the joints created by the welding process has been increasing in recent years. But each of these methods have always shown certain limitations in evaluation welded parts. Among these limitations is the need to cool down the part before the inspection process and the need for direct contact with the part. The infrared thermography method, as one of the advanced non-destructive inspection methods, has been widely used in the inspection of welded joints in recent years due to its many advantages. Among the advantages of the infrared thermography, it can be mentioned that it is non-contact, online, and has the ability to quickly evaluate a very large area of the part. Also, this process can check the health of the part during its working life in an assembled set. These unique features have turned the infrared thermography method into a method with a very high potential in the testing, process control and automation of the welding process .In addition, the ability to synchronize with the methods of artificial intelligence, machine learning, deep learning and signal and image processing has shown the potential of this method to be used more and more in modern industries in the future. Also, the research fields in this area are very untouched and many research gaps are felt in this field. In the upcoming research, an attempt has been made to create a suitable background for this process by presenting an overview of the principles of infrared thermography. Also, the applications of infrared thermography in the welding process, especially in non-destructive inspections, have been investigated, in which different methods of infrared thermography in non-destructive inspections have been described and explained.