Prakt. Met. Sonderband 38 (2006) 223
't sich da- Effect of the hot deformation on the microstructure of
onstanter Ti-10V-2Fe-3Al
agingtem-
F. Warchomicka', M. Stockinger , H. P. Degischer
" Institute of Materials Science and Technology, Vienna University of Technology,
leai Karlsplatz 13/E308, A-1040 Vienna, Austria
glegierten “ BÖHLER Schmiedetechnik GmbH & Co KG, Mariazellerstraße 25, A-8605 Kapfenberg,
dlung un- Austria
Dilatome-
ien durch-
engt. Dies ABSTRACT
rem Koh- J a ; ; :
ı während The microstructure of near beta titanium alloy Ti-10V-2Fe-3Al is very sensible to changes
eobachtet in the temperature and to deformation. In the present work, an evolution of the alpha
phase before and after hot deformation is studied by means of quantitative analysis of
SEM images. The specimens were heated up to 20 and 40K below the beta transus
25°C eine temperature and compressed at a constant strain rate of 0.01, 0.1 and 1s” up to 0.7 of
ie Wachs- true strain. A transformation of the alpha phase from a bimodal microstructure of chains of
nten kann alpha grains and fine acicular alpha phase to just rounded and elongated shapes within
rden, wo- the beta phase is observed to reach equilibrium after 5 minutes of holding time at both
anteil an- temperatures before deformed. During the compression at low strain rate the chains of
alpha grains become globular, while the chains are squeezed and elongated at high strain
rates. In addition, the beta sub-grains increase with decreasing strain rate.
rbide aus-
durch ein
nit sinken-
1. INTRODUCTION
In these days, the near beta titanium alloys are used to replace steel aircraft parts such as
landing gear due to the high specific strength and stiffness and their excellent workability
in forging process. Besides, the sensitivity of the microstructure to the heat treatments
101 gives a wide range of mechanical properties and application fields of these titanium alloys
| [1,2].
ree CMnAI Ti-10V-2Fe-3Al (Ti-10-2-3) has very good forgeability and a beta-transus temperature (Tg)
of 790 — 810°C [1], around 150°C lower than the well-known o, + 8 titanium alloy Ti64.
tution of Si In a previous work [3] it was shown that below Tg, the alpha phase became more globular
):813-822, and fragmented at low strain rates. At high strain rates, elongation and squeezing of the
alpha grains were also observed. It also corroborates the results of others works with
different initial microstructure and isothermal forging conditions [4, 5].
leduced Si The present work determines the behaviour of both alpha and beta phase of Ti-10-2-3
3 below Tg for different strain rates by analysing the microstructure along the specimen.
phase and Finally, the results are correlated with the effective local strain obtained by FEM
simulation.
1 M. Hackl:
ns by mag-
ous Alloys,
