Influência da temperatura do gás utilizado no processo GTAW sobre as características do arco e morfologia da solda

• Ano de defesa: 2018
• Autor(a) principal: Nilo Nogueira da Silva
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Minas Gerais; UFMG
• Palavras-chave em Português: Aquecimento do gás de proteção; Propriedades dos gases; Física da soldagem; Arco elétrico; Temperatura do arco; Soldagem GTAW; Gases Propriedades térmicas; Processos de fabricação; Engenharia mecânica; Soldagem
• Link de acesso: http://hdl.handle.net/1843/RAOA-BB3L8D

The electric arc is the most widely used heat source in the fusion welding of metallic materials, since it presents an optimum combination of characteristics. As a consequence, arc processes are of great industrial importance today and one of them is GTAW which uses a shielding gas responsible for affecting several characteristics of this process and, consequently, the properties of the welds produced. This paper aims to evaluate the influence of the preheating of the gas used in the GTAW process. A heating system was developed that allowed the variation and control of the gas outlet temperature during the tests. It was proposed a methodology of study of the electric arc, evaluating the values of voltage-current, profile, luminosity and thermal yield. The results showed that the gas temperature influenced the characteristics of the electric arc and the voltage values, mainly for lower currents. The heated gas provided an expansion of the arc presenting a larger area and greater light production. The thermal yield of the process decreased due to the higher heat losses. Welds were performed with different gas temperatures, observing its penetration and width. The study of the morphology of the welds showed that the increase of the gas temperature caused a greater fusion of the base metal at the weld edges than in the central region, being this effect related to the greater expansion of the arc. In this way, the use of preheated gas made it possible to obtain electric arc and welds with different characteristics of the conventional process