Thermo-Mechanical Study of TIG Welding of Ti-6Al-4V for Residual Stresses Considering Solid State Phase Transformation

Abstract

To overcome the detrimental effect of residual stress in welded joints, which affects the overall performance of the welded structure, this paper studies the magnitude and distribution of residual stress after welding and local post-weld heat treatment (PWHT). The coupled thermo-metallurgical-mechanical model for welding 6 mm thick Ti-6Al-4V (TC4) titanium alloy plates was established, the evolution of the SSPT and its effect on the residual stress were quantitatively analyzed, and a parametric analysis of local PWHT was performed. The results demonstrated that there was good agreement between the numerical results and the experimental data. Due to the cooling rate reaching 327 °C/s, the volume fraction of α、 in the fusion zone (FZ) reached 0.218 after welding and decreased by 90.83% after PWHT when the heating temperature was 700 °C. The peak value of the longitudinal residual stress can reach 686.4 MPa after welding with SSPT, which was 11.38% lower than that without SSPT, and it decreased by 65.6% after PWHT when the heating temperature was 900 °C. The research results demonstrate that SSPT has a significant effect on residual stress, and PWHT can obviously reduce the residual stress, which provides a certain reference for welding TC4 titanium alloy plates.

Numerical Simulation of Thermal Field and Performance Study on H13 Die Steel-Based Wire Arc Additive Manufacturing

“…In the WAAM process, the accumulation of heat due to rapid heating and cooling cycles resulted in significant residual stress within the cladding layer and neighboring regions, thereby affecting the performance of the formed components [10]. Residual stress was a pivotal factor influencing the mechanical properties, structural dimensions, and processing precision of the formed components [11]. Consequently, the adoption of methods such as prolonging inter-layer cooling periods held paramount significance in controlling residual stress.…”

“…Notably, the mechanical properties of components could be influenced by the inter-layer temperature as well. Wu et al [19] investigated that the component had a better surface finish and increased tensile strength when the inter-layer temperature was under 100 • C. Now that the computer simulation technology develops quickly, and numerical simulation technology can effectively predict the thermal behavior, transient stress during the welding process, and the residual stress and deformation afterwards [11]. Combined with the experiments, numerical simulation technology could improve manufacturing efficiency and save cost.…”