Comparação do processo de soldagem TIG e A-TIG em um aço baixo carbono com microadição de molibdênio
Comparison of the TIG and A-TIG welding process in a low carbon steel with molybdenum microadition
Mônica Aline Magalhães Gurgel, Ailanderson José Magalhães Gurgel, Vinicius Aleixo Silvestre, Frank de Mello Liberato, Andersan dos Santos Paula
Resumo
A soldagem TIG apresenta algumas limitações como a baixa taxa de deposição e penetração rasa nas juntas soldadas. Para suprir essas limitações foi desenvolvido o processo de soldagem A-TIG (Active Flux TIG Welding) onde aplica-se uma fina camada de fluxo sobre a superfície do material antes de ser soldado. Esse fluxo permite, através de mecanismos como a constrição do arco ou a convecção de Marangoni, aumentar a profundidade do cordão de solda. Desta forma, o objetivo deste trabalho é avaliar o incremento na profundidade, comparando a soldagem TIG e A-TIG com fluxo de Cr2 O3 , verificar as características morfológicas da microestrutura e os possíveis efeitos sobre a Ultramicrodureza ao longo da espessura do cordão de solda, em um aço baixo carbono com microadição de molibdênio. Os resultados indicam um ganho em termos de profundidade em comparação com o perfil geométrico da soldagem sem fluxo (TIG), o que corrobora para a boa eficiência do processo de soldagem A-TIG. A microestrutura encontrada na região central da zona fundida do cordão de solda consistiu em ferrita acicular (FA) e ferrita primária (FP) na soldagem TIG, como também a evidência da ferrita com segunda fase (FS) em conjunto com as demais fases na soldagem A-TIG devido à menor taxa de resfriamento resultante de uma maior energia de soldagem neste processo. Pela análise de Ultramicrodureza observou-se os maiores valores de dureza Berkovich (HT-115) e menores de dureza da indentação (Hit), para a soldagem A-TIG, na região do reforço do cordão de solda em relação a raiz, sendo observada influência da profundidade da solda nessas propriedades pelas fases resultantes na microestrutura após resfriamento com menor taxa, devido à maior energia de soldagem.
Palavras-chave
Abstract
TIG welding has some limitations, such as the low deposition rate and shallow penetration in the welded joints. To overcome these limitations, the A-TIG (Active Flux TIG Welding) welding process was developed, where a thin flux layer is applied to the material surface before being welded. This flux allows, through mechanisms such as the constriction of the arc or the Marangoni convection, to increase the depth of the weld bead. In this way, the objective of this work is to evaluate the increase in depth, comparing the TIG and A-TIG welding with Cr2 O3 flux, to verify the morphological characteristics of the microstructure and the possible effects on the Ultramicrohardness along the thickness of the weld bead in a low carbon steel with molybdenum microadition. The results indicate a gain in terms of depth compared to the geometric profile of welding without flux (TIG), which corroborates the good efficiency of the A-TIG welding process. The microstructure found in the central region fused weld bead consisted of acicular ferrite (FA) and primary ferrite (FP) in TIG welding, as well as evidence of ferrite with second phase (FS) in conjunction with the other phases in welding A-TIG due to the lower cooling rate resulting from higher welding energy in this process. The Ultramicrohardness analysis showed the highest hardness values of Berkovich hardness (HT-115) and lower indentation hardness (Hit), for A-TIG welding, in the region of the weld bead reinforcement in relation to the root, with influence of the weld depth on these property by the phases resulting in the cooled molten microstructure with a lower rate due to higher welding energy.
Keywords
References
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Submitted date:
06/26/2019
Accepted date:
05/18/2021
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