In-Situ Passive Infrared Thermography Application for the Assessment of Localized Mechanical Properties of TIG-Welded Inconel 625 Alloys

Abstract

Traditional evaluation of weld joint mechanical properties by destructive testing shows the limitations of these evaluation methods, including equipment limitations, high materials/testing cost, and challenging repeatability. This work presents an experimental approach for utilizing passive infrared thermography and tensile testing to evaluate the correlation between thermal and localized TIG-welded Inconel 625 joints' mechanical properties. The results show that different areas of interest behave differently during the tensile test. The dog-bone shaped TIG-welded samples were divided into five regions of interest on both sides of the weldment, of which two are repetitive on both sides of the sample representing Inconel 625 base metal alloy, heat-affected zones, and weld beads. The temperature change rate in these three regions varied from 0.17oC/min to 0.67oC/min as the tensile test progresses. The fractography analysis showed that the failure occurred within the weld beads, even though the highest temperature was observed in the heat-affected zones, suggesting higher strength in the heat-affected zones. This work's suggested evaluation method provides a powerful industrial and experimental tool to predict weld failure based on temperature changes during static loading.