ANALYSIS OF HEAT TRANSFER COOLING RATE AND ITS EFFECT IN THE GTA ALUMINUM ALLOY WELDINGALLOY WELDING
Elisan dos Santos Magalhães1; Ana Lúcia Fernandes de Lima E Silva1; Sandro Metrevelle Marcondes de Lima E Silva1
1 Universidade Federal de Itajubá - UNIFEI
doi:10.20906/CPS/COB-2015-0272
Resumo
An analysis of the heat transfer coefficient by convection and the emissivity in a GTA (Gas Tungsten Arc) welding process, on a 6060 T5 aluminum alloy is presented in this work. The authors' computational code was improved. In this software, an iterative BFGS (Broydon-Fletcher-Goldfarb-Shanno) inverse method was applied to minimize the amount of heat delivered to the plate when the appropriate sensitivity criteria were defined. The thermal properties were temperature dependent. The methodology was validated by accomplishing lab controlled experiments. Due to some experimental singularities the forced thermal convection induced by electromagnetic field and thermal-capillarity force could be disregarded. Significant examples of these singularities are the relatively small weld bead when compared to the sample size and the reduced time of welding process. An empirical correlation based on the local Nusselt number for flat plates was used to estimate the local heat transfer coefficient h. The presented method solved the thermal problem satisfactorily. The heat loss during the welding only by free convection proves to be more than 65% of overall cooling process.
Palavras-chave: Inverse problems; Heat flux and temperature estimation; GTAW process; Free convection; Thermal efficiency