Critical heat input threshold and orthogonal optimization of Ti–6Al–4V linear friction welding based on 3D thermo-mechanical simulation

Abstract

As a core component of high thrust-to-weight ratio aeroengines, the integrally bladed rotor (blisk) relies on high-performance linear friction welding (LFW) technology for its fabrication. To address the challenges of complex flash formation during LFW and the difficulty in directly observing thermo-mechanical coupling mechanisms through experiments, a three-dimensional (3D) thermo-mechanical coupled finite element model for the LFW of Ti–6Al–4V titanium alloy was established using the ABAQUS/Explicit platform. The Johnson–Cook constitutive model and adaptive meshing technology were employed to resolve computational divergence issues caused by material softening at elevated temperatures during solid-state joining simulations. By integrating an orthogonal simulation design, this study systematically decoupled and quantified the influence weights of vibration frequency, amplitude, and friction pressure on the evolution of the interface temperature field and axial shortening. Results indicate that the order of significance for the process parameters affecting axial shortening is: vibration frequency, friction pressure, and amplitude. Furthermore, no significant interaction effects were observed among these parameters. This study revealed a critical threshold relationship between thermal input and material rheological behavior: when the thermal input falls below the critical threshold of 2.25 × 107 W m−2, a stable viscoplastic layer fails to form at the interface. Upon exceeding this threshold, the axial shortening exhibits a linear positive correlation with the thermal input. Based on this relationship, the optimal process parameter combination was determined to be a vibration frequency of 25 Hz, an amplitude of 3.5 mm, and a friction pressure of 180 MPa. This combination achieved an ideal axial shortening of 3.5 mm, effectively balancing interface self-cleaning and material utilization. The 3D numerical model and critical heat input criterion established in this study provide numerical support and a quantitative theoretical basis for the engineering manufacturing of Ti–6Al–4V titanium alloy integral blisks.