Nondestructive yield strength estimation for 3D printed Ti-6Al-4V plates using eddy-current measurement

This study provides the development of a nondestructive yield strength estimation technique for metal 3D printed Ti-6A-l4V components using eddy-current measurement. Based on the relationship between the electrical conductivity and the grain size of the material, and the Hall-Petch relationship, the yield strength of metallic materials can be correlated by eddy-current phase value. First, a theoretical expression for the yield strength using the eddy-current phase value is explicitly derived. Then, for the experimental validation, the specimens with various yield strengths were produced by adjusting the cooling rate during the printing of each specimen. Then, the coefficients in the theoretical expression were estimated using the actual yield strength of specimens obtained via the conventional destructive tensile tests and the eddy-current phase values. Finally, the yield strength estimation performance was examined using the eddy-current signals obtained from test specimens with unknown yield strengths. The results indicate that the proposed technique can precisely estimate 3D printed Ti-6Al-4V components. The novelty of this study lies in (1) the derivation of an explicit relationship between the eddy-current phase value and the yield strength, (2) nondestructive yield strength estimation technique based on eddy-current testing, and (3) application to 3D printed Ti-6Al-4V plate specimens with various yield strengths.