Characterisation of solution annealed VT-14 titanium alloy using eddy current based electrical resistivity measurements

Abstract

This paper discusses characterisation of microstructures in Ti-4.5Al-3Mo-1V (VT-14) alloy specimens solutionized in the temperature range of 923K-1373K, using room temperature electrical resistivity measurements. Using phase angle of impedance change in eddy current coil as a parameter, calibration curve between resistivity and phase angle has been established using three reference specimens of known resistivity. The changes in the electrical resistivity of the specimens have been correlated with optical microscopy investigations. The electrical resistivity of unstable E phase has been compared with D and D´ phases and possible reasons for higher resistivity of E phase and lower resistivity of D´ have been given based on the rule of mixtures and scattering and mobility of electrons. The electrical resistivity of D´ martensite phase of the chosen VT-14 alloy has been determined as 1.04 D:-m. The studies reveal that it may be possible to identify the E transus temperature of D+E titanium alloys from the electrical resistivity data.

Microtexture region segmentation of eddy current testing data using a structural prior

“…In particular, it has been shown ECT is sensitive to changes in crystallographic orientation that alter MTR conductivity by as little as 6% [5][6][7][8]. While previous work has demonstrated the use of ECT for material property characterization (see, for instance, [9][10][11]), the main limitation of ECT is spatial resolution: features smaller than 350 µm can only be detected in isotropic, homogeneous materials [12]. Therefore, ECT is sensitive to MTR orientation but struggles to resolve MTR boundaries and size.…”