Relationships of microstructure and mechanical properties of high-strength metastable β titanium alloy TB18 after different heat treatments were investigated.The results show that many precipitation-free zones(PFZs)still retains in the β matrix of the TB18 alloy after solution treatment and aging at 525 ℃ for 4 h,where the alloy has an ultimate tensile strength of 1309 MPa,a yield strength of 1227 MPa,and an elongation of 6.6％.When the TB18 alloy is pre-aged at 300 ℃ for 2 h and aged,the microstructure and mechanical properties are not changed significantly.While the pre-aging temperature is increased to 400 ℃,there are no longer significant PFZs distributed in the microstructure after aging,and the strength and plasticity of the alloy are significantly increased,where the tensile strength,yield strength,and elongation are 1355 MPa,1278 MPa,and 7.0％respectively,showing a better strength-plasticity matching.In addition,all the tensile specimens are fractured in a mixed mode,but the specimens after solution,pre-aging at 400 ℃ and aging have fewer deconstructive features on the section and a greater proportion of ductile fracture.
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