Eventos Anais de eventos
COBEM 2021
26th International Congress of Mechanical Engineering
Fatigue and dwell-fatigue behavior of the Ti-6Al-4V titanium alloy with equiaxed microstructure
Submission Author:
Martin Ferreira Fernandes , SP
Co-Authors:
Martin Ferreira Fernandes, Verônica Velloso, Herman J. C. Voorwald
Presenter: Martin Ferreira Fernandes
doi://10.26678/ABCM.COBEM2021.COB2021-1156
Abstract
The Ti-6Al-4V alloy is applied in the aeronautical industry in the first stage of turbine engines. Gas turbine engines operate at a steady state after reaching the maximum stress, causing a phenomenon called the dwell effect, which is responsible for fatigue life debits when load holds are applied even at ambient temperatures. The dwell effect is relevant to the aeronautical industry to prevent premature structural component failures, such as fan discs in turbine engines. The most widely accepted dwell mechanism is a result of the difference in crystallographic orientation between α grains, which leads to stress redistribution. The Ti-6Al-4V and other titanium alloys show dwell sensitivity, which means that the fatigue life reduces when the maximum stress is kept constant for a certain period during each fatigue cycle, which corresponds to a duty cycle of a gas turbine engine, for example. In the present work, the fatigue behavior of Ti-6Al-4V with equiaxed microstructure was evaluated through fatigue and dwell-fatigue tests at room temperature. The damage mechanisms that control the fatigue and dwell-fatigue processes were discussed based on microstructural analysis, dwell-fatigue tests until fracture, and strain measurements. The dwell-fatigue test data was statistically analyzed through two-parameter Weibull distribution. The results showed that the Ti-6Al-4V alloy is dwell sensitive at room temperature with a dwell-fatigue life debit of 10.0 for dwell periods of 10 seconds at maximum stress of 97.5% of the yield strength.
Keywords
Dwell-fatigue, fatigue, Titanium alloys, Ti-6Al-4V, Turbine engines
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