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The conventional approach to temperature evolution in cyclic loading is explained by a hysteresis curve with three phases. However, it has not been matched with experimental data except in the beginning of the cyclic loading. Thus, this study suggests a new approach to temperature evolution with three phases in cyclic loading by plastic deformation using the thermoelastic effect. The sample was fabricated following ASTM D638 standard for cyclic loading, and the temperature was measured during the cyclic loading by an infrared camera. Thermography was used to observe partial heating caused by cracks. The results were evaluated with the correlation (R2) coefficient between temperature and the derived equation as 0.96 in phases 1 and 2. Also, the partial heating was observed showing the effect of cracks for the temperature evolution in phases 2 and 3. Based on these results, a new approach to temperature evolution in cyclic loading is suggested. [ABSTRACT FROM AUTHOR]

Tensile deformation behavior of nuclear grade Austenitic Stainless Steel (SS) and its weld joints fabricated by Gas Tungsten Arc Welding (GTAW) and Activated flux Gas Tungsten Arc Welding (AGTAW) processes were studied and correlated with relevant microstructural morphologies using Infrared Thermography (IRT) technique. The microstructure of base metal showed a complete austenite phase. GTAW Fusion Zone (FZ) exhibited both primary ferrite and primary austenite mode of solidification. Meantime, AGTAW FZ exhibited only primary austenite mode of solidification A strain rate of 4.4x10-4 s-1 was used during the tensile test of the base metal and weld samples. The failure locations of the base metal, GTAW and AGTAW samples were noticed at the center of the gauge portion, the base metal side away from Fusion Line (FL) and Heat Affected Zone (HAZ) respectively. Temperature variations of the base metal and weld zones were recorded in the form of thermograms using the IR camera at the different stages of the tensile deformation. During deformation study, peak temperatures of 39.2 oC, 38.8 oC and 34 oC were observed at the base metal, GTAW and AGTAW samples respectively. The lesser peak temperature of the AGTAW sample compared to the base metal and GTAW samples indicated that the AGTAW sample undergone lesser deformation. Moreover, tensile deformation behaviors of the base metal and weld samples were correlated with their microstructural morphologies using corresponding temperature curves.