Metallographic analysis of pure Ti submitted to Nd:YAG laser and TIG welding
Análise metalográfica do titânio puro submetido à soldagem laser Nd:YAG e TIG
Piveta, Ana Cláudia Gabrielli; Ricci, Weber Adad; Montandon, Andréia Affonso Barreto; Nagle, Maurício Meirelles
http://dx.doi.org/10.1590/S1807-25772013000100001
Rev. odontol. UNESP, vol.42, n1, p.1-6, 2013
Abstract
The welding method most commonly used in dentistry can not be applied to pure titanium and its alloys and its alloys due to high reactivity of titanium with the atmospheric elements must not be welded by common process. Objective: This study surveyed the characteristics of commercially pure titanium metal intact samples and those laser weld and tungsten inert gas weld. Material and method: Fifteen cylindrical rods were developments by using brass rods are patterns. The samples were invested in casings, subjected to thermal cycles, and positioned in a plasma arc-welding machine under argon atmosphere and vacuum, and titanium was injected under vacuum/pressure. Three groups were formed I: laser welding, II, III and TIG welding, without welding. The bodies of the test piece in group I and II were cut in half and welded by TIG and laser, respectively, and group III was maintained intact as control. The metallographic analysis was performed under magnification 50×, 100× and 200× microscope. Result: The results obtained in the micrographs, the commercially pure titanium showed an equiaxed grain morphology of α phase, the laser weld bead showed martensitic structure and TIG Widmanstätten microstructure. Conclusion: Martensitic microstructure is in agreement with the high cooling rate from the laser welding process. Martensitic and Widmansttäten structures are more refined when compared to the microstructure of the base metal.
Keywords
Dental soldering, titanium, dental prosthesis, dental implantation.
Resumo
Os métodos de soldagem mais utilizados em Odontologia não podem ser aplicados ao titânio puro e às suas ligas em função da alta reatividade do titânio com elementos atmosféricos; dessa forma, o mesmo não deve ser soldado por processo comum. Objetivo: O objetivo deste trabalho foi avaliar a característica metalúrgica do titânio comercialmente puro sem solda e submetido aos processos de soldagem a laser e TIG. Material e método: Foram confeccionados 15 corpos de prova em titânio comercialmente puro, cinco para cada condição, na forma de hastes cilíndricas, obtidas por fundição odontológica, sob atmosfera de gás argônio e vácuo, com calor produzido por um arco voltaico, com a injeção do titânio sob vácuo-pressão. Três grupos foram formados I: soldagem a laser; II: soldagem TIG, e III: sem solda. Os corpos de prova do grupo I e II foram seccionados ao meio e soldados por TIG e por laser, respectivamente; o grupo III foi mantido sem corte e sem solda, como controle. A análise metalográfica foi realizada sob aumentos de 50×, 100× e 200×, em microscópio. Resultado: Pelos resultados obtidos nas micrografias, o titânio comercialmente puro apresentou uma morfologia de grãos equiaxiais da fase α, o cordão de solda a laser apresentou estrutura martensítica e, na TIG, microestrutura Widmanstätten. Conclusão: A microestrutura martensítica é condizente com a alta taxa de resfriamento proveniente do processo de soldagem a laser. As estruturas martensítica e Widmansttäten são mais refinadas quando comparadas à microestrutura do metal base.
Palavras-chave
Soldagem em odontologia, titânio, prótese dentária, implante dentário.
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