Strain path effects on titanium alloy Timetal-834 under hot working conditions
Date
2007
Authors
Blackmore, M.
Wynne, B.
Beynon, J.
Davies, P.
Editors
Chandra, T.
Tsuzaki, K.
Militzer, M.
Ravindran, C.
Tsuzaki, K.
Militzer, M.
Ravindran, C.
Advisors
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Journal article
Citation
Advanced Materials Research, 2007; 15-17:959-964
Statement of Responsibility
M.L. Blackmore, Bradley P. Wynne, John H. Beynon, Peter S. Davies
Conference Name
Abstract
<jats:p>The effects of strain path reversal under hot working conditions on the microstructure
and crystallographic texture in the near-α titanium alloy Timetal-834 have been studied using high
resolution electron backscatter diffraction (EBSD). The main objective of the work was to
investigate the potential effect strain path may have on breaking up the well known clustering of
similarly orientated primary alphas grains in the alloy, which significantly reduces its low cycle
dwell fatigue lifetime. Deformation was carried out using forward torsion to an equivalent strain of
0.9 and forward/reverse torsion of two equal steps to produce a total strain of 0.9. The tests were
performed at a typical industrial forging condition of 990°C (~50% alpha, ~50% beta) at an
equivalent tensile strain rate of 2s-1. Investigation of the microstructure showed the primary alpha
grains to align with the direction of torsion for the forward test and return to an equiaxed shape on
strain reversal, though a significant numbers of deformation twins are formed and retained after the
full strain reversal. Analysis of the texture of the starting material showed the typically clustering
of primary alpha grains, which upon forward torsion and forward/reverse torsion did not break
down. This indicates that during a typical forging operation the clustering of similarly orientated
primary alpha grains inherited from the as-received billet will not be reduced. This suggests that
improved in-service performance of this alloy can only be achieved by reducing the clustering
upstream in the manufacture of the billet.</jats:p>
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© (2007) Trans Tech Publications, Switzerland