Fig. 1 Schematic of experimental procedures in this work (RD, TD, and ND represent rolling direction, transverse direction, and normal direction for the plate, respectively)

Fig. 2 Microstructure of TA15 titanium alloy before hot rolling: a SEM microstructure, b EBSD microstructure, c XRD spectrum

Fig. 3 Microstructures of TA15 titanium alloy after rolling at 950 °C: a, b SEM microstructure, c EBSD microstructure, d XRD spectrum, e volume fractions and average sizes of α phase and β phase, and f the distribution of misorientation angle

Fig. 4 SEM microstructures of hot-rolled TA15 titanium alloy after annealing at different conditions: a, e A650-30, b, f A750-30, c, g A850-30, d, h A750-60

Fig. 5 a XRD spectrum and b the volume fractions and average sizes of α phase and β phase of hot-rolled TA15 titanium alloy after annealing at different conditions

Fig. 6 a1-d1 EBSD maps, a2-d2 distribution of LAGBs and HAGBs, and a3-d3 distribution of misorientation angle of hot-rolled TA15 titanium alloys after annealing at different conditions: a1-a3 A650-30, b1-b3 A750-30, c1-c3 A850-30, d1-d3 A750-60

Fig. 7 Volume fractions of LAGBs and HAGBs in α phase and β phase of hot-rolled specimens after annealing at different conditions

Fig. 8 Distribution of grain boundaries of hot-rolled specimens after annealing at different conditions in equiaxed α phase and acicular α phase: a, e A650-30, b, f A750-30, c, g A850-30, d, h A750-60

Fig. 9 Pole figures (PFs) of hot-rolled TA15 specimen of a α phase and b β phase

Fig. 10 PFs of hot-rolled TA15 specimens after annealing at different conditions of α phase and β phase: a, b A650-30, c, d A750-30, e, f A850-30, g, h A750-60

Fig. 11 Schmid Factors mappings of hot-rolled specimens after annealing at different conditions: a A650-30, b A750-30, c A850-30, d A750-60

Fig. 12 a Engineering stress-strain curves and b associated mechanical properties of hot-rolled TA15 titanium alloy after annealing at different conditions

Fig. 13 Comparison of the mechanical properties between other TA15 titanium alloys and this work

Fig. 14 Groove structure and the thickening phenomenon of acicular α phase in hot-rolled TA15 titanium alloy after annealing at different temperatures for 30 min: a 650 °C, b 750 °C, c 850 °C

Fig. 15 Calculated yield strength and experimental yield strength of different annealed specimens