Microstructure and mechanical properties of cast and heat treated Ti–6.55Al–3.41Mo–1.77Zr alloy

Abstract

α+β titanium alloy with a composition of Ti–6.55Al–3.41Mo–1.77Zr (mass fraction, %) was cast into bars in a graphite mould using vacuum induction skull melting furnace (ISM). The cast bars were hot swaged at 700 °C and then heat treated by two different regimes which resulted in fine and coarse lamella structures, respectively. The grain size of the as-cast structure was estimated to be 660 μm and the swaged samples obtained a very fine grain size in the range of 50 μm. The overall best combination of hardness, tensile properties, and wear resistance of the α+β titanium alloy was achieved by heat treating the samples at 1050 °C for getting fine lamellar structure. The maximum compression strength was reported for the heat treated samples at 800 °C with coarse lamella structure. The minimum wear rate was reported for the heat treated samples with fine lamellar structure and the maximum wear rate was obtained for as-cast samples due to its coarse and heterogeneity microstructure.