Experimental investigation to evaluate Johnson-Cook parameters of additively manufactured Ti6Al4V titanium alloy

Abstract

Direct Metal Laser Sintering (DMLS) is a highly versatile and efficient Powder Bed Fusion (PBF) additive manufacturing technique that is widely utilized in various industries such as aerospace, automobile, and biomedical. The present study investigates the anisotropic and plastic behavior of DMLS-produced Ti6Al4V through the Johnson-Cook plastic model. Further the same was validated through dynamic simulation, focusing on the comparison of stress-strain curves for different strain rates and deposition directions. Dynamic compression tests were conducted using a Split Hopkinson Pressure Bar (SHPB) apparatus. The results revealed significant strain-rate hardening effects on the top and side surfaces. Moreover, anisotropic behavior was observed when comparing stress-strain curves at the same strain rate. The material exhibited a higher yield strength of ~1784 MPa and lower elongation of ~0.118 in the side surface direction, indicating increased strength with reduced ductility. The study also investigated the morphology of DMLS-produced Ti6Al4V, revealing anisotropic behavior and the formation of adiabatic shear bands (ASB) under different strain rates. These findings emphasize the significance of considering strain rate effects in failure mechanisms and structural response. A comparison between simulation and experimental data highlighted disparities in the plastic region.