Macrosegregation and Macrostructure of Plasma Arc Melted Ti-6Al-4V

摘要

Samples of as-cast plasma arc cold hearth melted Ti-6Al-4V have been analysed to reveal the extent and pattern of macrosegregation of Al, V and fe in longitudinal and transverse orientations. These have been compared to similar data obtained from commercial Ti-6Al-4V manufactured by triple vacuum arc remelting and from electron beam cold hearth melting using the same analysis techniques. The results show that the levels of macrosegregation in each of the elements is comparable in all materials, with the exception o Al in the electron beam-based material which has twice the spread of the other samples. The plasma melted material exhibits a macrosegregation pattern consisting of an irregular distribution of localised highs and lows of concentration with no long range pattern in either the longitudinal or transverse directions. The non-plasma material all show the classical centre-to-edge pattern associated with Ti alloys. The reasons for this difference are discussed but remain unclear.