Effect of quenching temperature on structure and properties of titanium alloy: Physicomechanical properties

Fracture surface analysis of a quenched (α+β)-metastable titanium alloy

“…1, Table 1). Thus, the average dimple diameter of the quenched specimens correlates with the average β-grain size, which is determined by the primary α-phase fraction having a size of about 3 μm for the quenching temperature ranging between 700 and 775 °С, 5 μm for T q = 800 °C, 10 to 13 μm for T q = 825-850 °C and 70 μm for T q = 875 °C, according to the data reported in [5]. Thus, we conclude that fracture is initiated at the interphase α/β-boundary, and then it propagates into the β-grain body, this being accompanied by the formation of dimples with dimensions comparable to the β-grain size.…”

“…However, the crack propagates changing its direction in contrast to the shear zone, where the only direction is typical. We suppose that this effect is due to the strain-induced β-αʺ-transformation during the tensile test and the appearance of αʺ-martensite in the structure of the alloy, according to the data found in [5]. As a result, the yield strength decreases substantially and the strain hardening value increases.…”

“…However, the power of cold working depends on the phase and structural conditions, which mainly determine the ductility of the alloy. The structure, phase composition and mechanical properties were discussed in [4,5] depending on the quenching from a wide range of temperatures. Nevertheless, the relation between the fracture during tensile testing and the phase composition, as well as the level of alloy ductility after quenching, has yet to be studied.…”

Effect of low temperature thermomechanical treatment on the phase composition and properties of a two-phase titanium alloy

“…As a result of accommodative processes taking place due to the difference in the specific volumes of the original (α'') and formed (α') martensite crystal lattices, a β a -solid solution was formed, with an abnormally large lattice parameter (0.33 nm). In [5] it was found that, during continuous heating of a cold-worked alloy, aging proceeds actively in the temperature range of 400...650 °C. It was attributed to the decomposition of the metastable phases (α', β a ).…”

“…However, the phase transition of the second order might occur in β-metastable Ti-alloys with K β of about 1 [4], and this would definitely result in the physical and mechanical properties. We have already studied the structure, phase composition and properties of the VT16 alloy after ST followed by cold deformation and subsequent continuous heating at a temperature range including its aging temperature range [5,6]. In [6] the ST heating temperature was taken as (β transus -10) °C.…”