Efeito de múltiplos ciclos de solubilização sub-solvus delta e envelhecimento na microestrutura e propriedades mecânicas da superliga 718

The nickel based superalloy 718 was developed to meet the requisites of components for aircraft engines, due to its excellent creep resistance up to 650°C. During the maintenance of the engines, the components can be submitted to successive repair procedures, however the mechanical properties can be estimated solely during the project development. In order to understand the uncertainties during the repair procedures that can result in cost to the production chain, the present work aims to evaluate the evolution of the microstructure and the properties of tensile and hardness after being submitted to successive cycles of sub-solvus δ solution annealing (954°C/1h) and aging (760°C/5h + 649°C/1h). Forged and cast samples had its microstructures observed by optical and scanning electron microscopes with the identification of precipitates made by the morphologies. Grain size measurements, hardness measurements and tensile tests were performed. It was observed that δ precipitation at grain boundaries occurred, keeping a refined microstructure. However, there was a crescent evolution of the δ particles in volume and average size. As a consequence, a reduction of the Nb available to the formation of γ” occurred, the main hardening phase, evidenced by the reduction of the ultimate tensile strength, yield strength and hardness.

Grantor dc:publisher

Universidade Federal do Rio de Janeiro

Year dc:date.issued

2017

Author dc:creator

• Oliveira, Alexandre de

Advisor dc:contributor.advisor

• Araújo, Leonardo Sales

• Liga metálicas
• Tratamentos térmicos
• Microestrutura
• Propriedades mecânicas

Statement dc:rights

• Acesso Aberto

Language dc:language

por

Handle dc:identifier.uri

http://hdl.handle.net/11422/5944

OAI identifier oai:identifier

oai:pantheon.ufrj.br:11422/5944