Abstract:The effects of hot compression, hot rolling and post-rolling annealing on microstructure and tensile properties of Ti-6Al-4V were analyzed. Hot compression tests were conducted in the temperature range of 800−1 075 °C and at strain rates of 0.001−1 s⁻¹, and the relations between the characteristic points of flow curve and processing variables were developed. Two passes of hot rolling test with total reduction of 75% were performed in the temperature range of 820−1 070 °C and at constant strain rate of 2 s⁻¹. After hot rolling, some specimens were subjected to heat treatment at 870 °C and 920 ‌°C for 2 h followed by air cooling. Hot rolling in beta phase field resulted in coarse beta grains transforming to martensite by cooling. Otherwise, rolling in the alpha/beta phase filed gave rise to a partially globularized alpha microstructure. The post-rolling heat treatment completed the partial globularization of alpha phase in two-phase region and otherwise broke down the martensitic structure of beta-rolled samples. Tensile tests showed that the strength characteristics as well as elongation decrease significantly with increasing the rolling temperature from the two-phase to the single-phase region. Increasing heat treatment temperature contributed to lower strength for the specimens rolled in two-phase region and higher strength characteristics for the beta-rolled specimens.

Key words: recrystallization; hot rolling; hot compression; heat treatment; globularization