The Effect of Al and V on Microstructure and Transformation of β Phase during Solution Treatments of Cast Ti-6Al-4V Alloy

Abstract

In this study, the effect of α and β those stabilizers on the microstructure and phase transformation of cast Ti-6wt%Al-4wt%V alloy at various solution treatment temperatures was investigated. The dependence of the transformation behavior of the β phase during the solution treatment and its dependence was determined by the partitioning of α and β stabilizing elements. Solution treatments were conducted at 850 ~ 1050 ℃ for 0.5 h and, followed by water quenching. Aging treatments at 550 ℃ for 24 h were then performed. The α' martensite was transformed from the β phase when the concentration of vanadium in the β phase was less than 4.27 at%, while the metastable β phase did not transform to α' martensite when the concentration of vanadium in the β phase was over 5.14 at%.

Effect of Heat Treatment on the Material Property and Cell Viability of Wire Arc Additively Manufactured Ti6Al4 V

“…However, the cooling rate in the WAAM process is not uniform, which leads to formation of inhomogeneous α, β, and α′ phases that consequently generate anisotropy in the deposited structure. , Figure f shows the continuous cooling transformation of the β-phase into the α + β-phase. During the solution treatment process, the samples were heated to the β-Ti region (950 °C), close to β-transus temperature, to dissolve the α-phase, followed by water quenching to suppress the transformation of the β-phase into the α-phase, leading to a prominent presence of α′-phases within its structure, as shown in eq . Subsequently, during the aging, the matrix was subjected to prolonged heating within the martensite start temperature ( M s ) and martensite finish temperature ( M f ) range, which rejects the β-phase stabilizing element, V, from the α′-phase, leading to the transformation of the α’-phase into a fine α + β-phase as presented by eq , (Figure f).…”