Effect of Solution Treatment on Strength and Toughness in Ti-10V-2Fe-3Al Alloy

The effect of the solution treatment in the range from two phase (α+β) to β-fields on the strength, ductility, and toughness of Ti-10V-2Fe-3Al alloy has been investigated. When the solution treatment was performed in the temperature range from 973 to 1173 K, the 0.2% yield strength showed a noticeable decrease at 1043 K or higher and was only about 450 MPa or less. In contrast with these variations the elongation showed a great increase. It is considered that these variations of the 0.2% yield strength and elongation arise from the stress induced martensitic transformation due to the instability of the β phase matrix. After aging at 783 K for 28.8 ks, the 0.2% yield strength did not show any sharp decrease like that in the solution treated condition. Both elongation and reduction in area showed a considerable low values at 1073 K or higher. However, the detrimental effect of coarsening of β grain size was not detected from the mechanical properties because of their very small absolute values of ductility. On the other hand, the notch tensile strength and KIC were not affected by the microstructural change at the same strength level. Notch tensile strength was not affected by the strength but KIC showed a decrease with an increase of the strength level. It was confirmed that the superior combination of strength, ductility, and toughness after aging treatment at 783 K for 28.8 ks was obtained with the solution treatment at sub-transus temperature of 1023∼1043 K.