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Regular version of the site

Article

Characterization of OT4-1 Alloy by Multi-Dome Forming Test

Materials. 2017. Vol. 10. No. 8. P. 1-10.
Zakhariev I. Y., Aksenov S. A., Kotov A., Колесников А. В.

In this study, the rheological characteristics of a titanium alloy have been obtained by
multi-dome bulging test. Free bulging process is an experimental technique that can be used to
characterize material in conditions of biaxial tension during superplastic, as well as conventional,
hot forming. The constitutive constants are calculated on a base of the information about the bulge
geometry, applied pressure, and forming time. A multi-dome forming test allows one to reduce the
number of the experiments required for the characterization, since every multi-dome test produces
several domes of different size. In this study, a specific die for multi-dome test was used. The die
has six holes with different radiuses of 20, 25, 30, 35, 40, and 45 mm. During a test, the specimen
is clamped between blank holder and die holder, heated to a specific temperature, and formed by
applying constant gas pressure. The experiments were conducted at different temperatures for OT4-1
titanium alloy. The constitutive constants were obtained by processing the experimental data using
two different techniques and compared with tensile test results. In order to estimate the influence of
friction on the experimental results and to verify obtained material characteristics, finite element (FE)
simulation was performed. Finally, the results of FE simulation were compared with the experimental
data. The results of the simulation show the advantage of material characterization based on multi
dome tests and its interpretation by inverse analysis. The deviations produced by the effect of friction
are more significant when the direct approach is applied instead of inverse analysis with a semi
analytical model of the bulging process.