적외선 열화상 기법을 이용한 용접부의 결함 비파괴 측정기법

Non-destructive Measurement Technique of Welding Using Infrared Thermography Technique

Recently, the Infrared-Thermography Technique is widely used for nondestructive testing (NDT) of structures due to its convenience. In particular, various techniques have been applied to detect imperfections such as surface defects and welding defects of steel structures. This paper is a part of a study to detect defects in weld zone in steel structures using Infrared Thermography techniques. The temperature on steel structures surface depends on the material and thermal properties such as specific heat, thermal conductivity, and thermal diffusion coefficient. In this study, Infrared thermography technique was used to detect the information on the diagnosis of steel structure in welds. Test specimens were prepared with artificial defects, then the passive and active methods were used to determine damages on the steel structures in welds as well to detect the defects. Finally, defects were observed by comparing infrared thermal image and surface temperature data of defected area with the normal area. Furthermore, the defects were measured using the standard deviation of the temperature corresponding to the weld. For normal weld, the standard deviation of the temperature corresponding to the weld zone was low; although the standard deviation of the weld defects zone was high.