;Effect of different solution temperature on microstructure and mechanical properties of water quenched SP-700 titanium alloy were studied by analysing the microstructure and mechanical properties .
The results indicated that SP-700 titanium alloy quenched from single-phase region (950℃ and 900℃), the microstructure consists brittle needle shape α" martensite phase and softer retained β phase (βr) base phase, it shows poor tensile strength and ductility. When quenched from two-phase region (850℃ and 800℃), the room temperature is between Ms and Mf, the microstructure consists primary α phase (αp), α" martensite phase and retained β phase (βr) base phase, during tensile test, alloy shows obviously “stress-induced martensite phase transformation”, will have a significant hardening properties. As the solution temperature at 800℃, contents more hard αp phase, will have a higher yield strength, ultimately lead to high strength and high ductility, while the tensile test. Furthermore, quenched from lower temperature (750℃), the Ms temperature of β phase has been below room temperature, the microstructure are retained β phase (βr) and primary α phase (αp), there are no martensite transformation during water quenching and tensile test process, doesn’t have hardening properties, but with the optimum toughness.
In conclusion, SP-700 titanium alloy quenched from two-phase region, the mechanical properties are conform to the titanium armor plate material specification (MIL-DTL-46077), which contains high hardness and elongation, and the solution temperature at 800℃ has best hardness and elongation.