Abstract: A novel low-cost high-strength β titanium alloy Ti-5Al-3.5Fe-7Mo-4Cr was self-designed, and the effect of solution treatment and aging on its microstructure and tensile properties was investigated by means of room temperature tensile testing, EBSD, SEM, TEM and EDS analysis. The results show that compared with that solution treat in single-phase region and aging, the properties of the alloy solution treated in α+β two phase region and aged are better. Under these two different solution treatment systems, as the aging temperature increases, the precipitation amount of secondary α phase and strength of the alloy both increase first and then decrease, while the elongation shows an increasing trend. When the aging temperature is higher, the needle-like secondary α phase grows and its interspacing increases. After solution treatment at 820 ℃ for 0.5 h and aging at 440 ℃ for 8 h, the tested titanium alloy achieves good strength-plasticity match, with the tensile strength of 1257 MPa, yield strength of 1135 MPa, and elongation of 4%, meeting the strength requirements of high-strength titanium alloys. The high strength of the tested β titanium alloy is mainly due to the second phase strengthening, smaller secondary α phase interspacing, the increase in volume fraction of α phase and hierarchical size structure having a significant strengthening effect on the alloy.

Key words: Ti-Al-Fe-Mo-Cr β titanium alloy, solution treatment and aging, microstructure, tensile properties