Estudo do tratamento de oxidação em diferentes microestruturas da liga de titânio
Study of the treatment of oxidation in different microstructures of the titanium alloy
FabrÃcia Assis Resende Gonçalves, Renata Jesuina Takahash, Danieli Aparecida Pereira Reis
Resumo
A liga Ti-6Al-4V é a liga de titânio mais usada em aplicações estruturais de engenharia pela combinação de resistência mecânica em altas temperaturas, baixa massa especÃfica e resistência à corrosão. Contudo, uma das limitações da liga é a afinidade do titânio por oxigênio a partir de 600 °C, tornando a liga susceptÃvel à oxidação. Portanto, neste trabalho se estudou a oxidação na liga de titânio (Ti-6Al-4V) com diferentes microestruturas: equiaxial, Widmanstätten, martensÃtica e bimodal obtidas por tratamento térmico. As amostras com as diferentes microestruturas foram submetidas a tratamento térmico de oxidação nas temperaturas de 500, 600, 700 e 800 °C por 48 horas ao ar. Os resultados mostraram que as amostras oxidadas formaram uma pelÃcula de óxido sobre a superfÃcie que foram caracterizadas por microscopia óptica e microscopia eletrônica de varredura, por medição da variação da massa das amostras e por análise de microdureza. A microestrutura Widmanstätten apresentou-se mais resistente à oxidação pela formação de grãos mais grosseiros e formação de pelÃcula de óxidos mais espessos e mais resistentes a deformação localizada.
Palavras-chave
Abstract
The Ti-6Al-4V alloy is the most commonly used titanium alloy in structural engineering applications by combining mechanical strength at high temperatures, low specific mass, and corrosion resistance. However, one of the limitations of the alloy is the affinity of titanium for oxygen from 600 °C, making the alloy susceptible to oxidation. The purpose of this work was to study the oxidation of titanium alloys (Ti-6Al-4V) with different microstructures: equiaxial, Widmanstätten, martensite, and bimodal, which were formed from heat treatment. The samples with different microstructures were subjected to oxidation heat treatment at temperatures of 500, 600, 700, and 800°C for 48 hours in the air. The oxidized samples formed an oxide film on the surface, which was characterized by optical and scanning electron microscopy, by measuring the mass of the samples and by microhardness analysis. The Widmanstätten microstructure was more resistant to oxidation by the formation of coarser grains and the formation of thicker oxide films and more resistant to localized deformation.
Keywords
Referências
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Submetido em:
10/06/2019
Aceito em:
29/09/2020
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