In alloys susceptible to Strain-Induced Martensitic Transformation (SIMT) such as metastable austenitic steels, the extensive shearing imposed during Severe Plastic Deformation (SPD) processes accelerates transformation kinetics and enhances material strength. However, compressive mean stress inherent to such processes acts detrimentally to the transformation. The present study investigated the potential of Low-Speed High-Die-Angle (LSHDA) wire drawing as an SPD process for manufacturing ultra-high strength 304 L steel wires by leveraging a controlled state of positive mean stress using atypically high die semi-angles (20 \(\:^\circ\:\) to 40 \(\:^\circ\:\) ). The tribo-plasticity analysis of this process was conducted using slab method combined with a physically-based, regime-switching Thermal Mixed Lubrication (TML) model capable of predicting the onset of local lubrication breakdown under extremely high die pressures. Furthermore, a novel constitutive-geometric redundancy factor was proposed to accurately capture the coupled effects of highly localized deformation geometry and material strain hardening on the extent of redundant shearing. The theoretical framework was augmented with a Particle Swarm Optimization (PSO) scheme for inverse calibration of constitutive parameters of the proposed friction model and the redundancy coefficient against experimental measurements. The framework demonstrated high fidelity in deriving governing parameters of the frictional model, accurately predicting the onset of surface scoring due to high die pressure. Moreover, the calibrated redundancy factor provided new insights into the extreme inhomogeneous deformation caused by unconventionally high die angles. Experiments confirmed that maintaining low drawing speeds and efficient lubrication entirely prevented central bursting and surface defects, enabling the successful manufacture of defect-free, high-strength products via LSHDA wire drawing.
