Numerical prediction of tensile yield strength and micro hardness of Ti6Al4V alloy processed by constrained bending and straightening severe plastic deformation

This paper presents a numerical prediction of tensile yield strength and hardness properties of Ti6Al4V alloy processed by constrained bending and straightening (CBS) severe plastic deformation (SPD) technique. The CBS method has been proposed to enhance continuous processing of metal sheets and improve magnitude and homogeneity of entailed tensile, hardness and strain properties. The CBS simulation was performed on Ti6Al4V alloy rectangular sheets at N = 2, N = 4 and N = 6 passes respectively denoted as N2, N4 and N6 each combined with F = 12 mm, F = 6 mm and F =4 mm feed lengths respectively denoted as F4, F6 and F12. ABAQUS Standard FEA Software was used to determine magnitude and homogeneity of induced equivalent plastic (EP) strain. Applying the power law strengthening equation, simulated EP values were used to predict magnitudes of tensile yield stress and hardness of the samples. Numerical results were validated with experimental results at N2, N4, N6 passes for F6, F12 feeds. Simulation results showed that magnitude and homogeneity values of EP strain, yield strength and hardness were the highest at N6F4 followed by those at N6F6 and N6 F12 respectively. Experimental results showed that the yield strength and hardness had the highest increases by 34.5% and 24.4% respectively at N4F6 over that of as received (AR) samples. A comparison between simulation and experimental results on yield strength and hardness showed direct corelation at N2, N4 passes. However a relative inverse corelation was observed at N6 pass due to saturation of hardening and onset of material excessive yield after N4 pass.