Abstract
Effects of β-stabilizer content in β phase at solution treatment temperature on microstructures after quenching from solution temperature. aging characteristics, and tensile properties were investigated by using 9 α-β titanium alloys(Ti-Al-V-Sn-Zr-Mo-Cr-Fe system). The main results obtained are as follows:
(1) Partitioning of each element to α and β phases at solution treatment temperature could be well estimated from each Ti-j (j=Al, V, etc.) binary phase diagram.
(2) Phase stability of β phase was considered to relate well with electron-atom ratio(e/aβ). Phase transformations in the alloys during quenching could be classified by e/aβ. From changes of electrical resistivity during heating, it was considered that athermal and isothermal ω phase were formed in the alloys GT-33, 45, and 46(e/aβ=4.06-4.16).
(3) Effects of microstructural and compositional factors Volume fraction(Vα), grain diameter(dα), and degree of solid-solution strengthening(dDEα) for primary α phase, e/aβ for prior β phase, and aging temperature(Tag) on tensile properties at 300°C were examined by using multiple regression analysis. Following regerssion equations were obtained.
σu(kgf/mm2)=207.72-318.29Vα+119.43Vα·dDEα+178(1-Vα)·(e/aβ-4)-19(1-Vα)·Tag/100
El.(%)=-19.86-39.28Vα+13.08dDEα+2.95Tag/100
