A comparative study of the mechanical properties of high-strength β-titanium alloys

The mechanical properties of four commercial β-titanium alloys (TIMETAL-LCB, Ti-15-3, β-21S, and VT22) were compared in the solution-treated-and-aged (STA) condition following thermomechanical processing comprising β solid solutioning, cold deformation (CD), continuous rapid heating, and final aging. The peak temperature during the rapid heating step was chosen to obtain either a recovered or recrystallized condition and thereby to control the distribution of residual deformation defects, which in turn influenced the size and distribution of α precipitates in the final microstructure. It was established that a good balance of high strength (in excess of 1600 MPa) and reasonable ductility could be obtained if a fine-grain microstructure with a β grain size of ∼10 μm was formed by recrystallization. The development of such a fine-grain size enabled a reduction in the aging temperature and thus increased the strength while maintaining ductility within the desired limits. In this respect, the properties could be varied to a great extent by varying the rate of heating to the aging temperature. On the other hand, aging of the recovered condition also led to a strength level of approximately 1600 MPa but with generally lower ductility than in the fine-grain, recrystallized condition. Another distinctive feature of the recovered condition was that the properties were relatively insensitive to the rate of heating to the aging temperature.