Annealing Heat Treatment for Homogenizing the Microstructure and Mechanical Properties of Electron-Beam-Welded Thick Plate of Ti-6Al-4V Alloy

Abstract

In the application of Ti-6Al-4V to aerospace structural components, when welding thick plates similar of the thickness of the components, microstructure and hardness gradients emerge between the base material (BM) and the joint. This leads to the issue of significant stress concentration in the BM under tensile stress. To address this problem through post-welding heat treatment, this study conducted heat treatments at temperatures both below (mill annealing, MA) and above the beta-transus temperature (beta annealing, BA) on electron-beam weldments of 18 mm thickness Ti-6Al-4V plates. Subsequently, microstructures and hardness were analyzed at different depths from the upper surface and areas (fusion zone (FZ), heat-affected zone (HAZ), and BM), and tensile properties were measured at various depths. The results indicated that α′ observed in FZ and HAZ was resolved through both MA and BA. Particularly after BA, the microstructural gradient that persisted even after MA completely disappeared, resulting in the homogenization of widmanstätten α + β. Consequently, after BA, the hardness gradient in each zone also disappeared, and the tensile strength was higher than in just-welded and MA heat-treated plates.

Electrochemical characteristic and microstructure of Ti-6Al-7Nb alloy by centrifugal casting for orthopedic implant based on ageing time variations

“…Centrifugal casting Ti-6Al-7Nb alloy under investigation in this work was formed into a rod. A vacuum electric arc furnace was used to melt wrought Ti-6Al-7Nb rod [31]. A rod was created by casting the molten metals.…”

“…Meanwhile, primary α (α p ) and secondary α precipitation (α s ) in titanium alloys are required to achieve perfect strength-plasticity matching and increased corrosion resistance. In addition, coarse columnar grains can be changed to become more homogeneous with solution treatment and aging (STA), thereby increasing the corrosion resistance of the Ti-6Al-4V alloy [31].…”

Effects of Aging Treatment on the Microstructures and Mechanical Properties of a TC18 Alloy

“…Solution plus single aging was usually used by some researchers who found that the α p phases are highly sensitive to the Materials 2024, 17, 570 2 of 15 solution temperature, while the α s phases are greatly affected by aging conditions [16,22]. Moreover, the precipitation of α s phases could significantly enhance the properties of Ti alloys [28][29][30]. Shaha et al [31] reported fine α phases and low residual stress in the Ti55511 alloy, resulting in improved mechanical properties.…”

Numerical Simulation on Solidification during Vertical Centrifugal Casting Process for TC4 Alloy Wheel Hub with Enhanced Mechanical Properties

“…Ti-6Al-4V (TC4) alloy, as a two-phase ( α + β ) titanium alloy, displayed remarkable structural stability, excellent mechanical properties, high plasticity, toughness, and resistance to high-temperature deformation [ 1 , 2 , 3 ]. Due to these characteristics, the TC4 alloy was extensively applied in various areas, such as compressor blades and impellers of jet engines, landing gear wheels, aircraft accessories, and pipes [ 4 , 5 , 6 ]. Various complex TC4 alloy parts were commonly fabricated through methods such as casting, forging, and machining [ 7 , 8 , 9 , 10 ].…”