Residual stress measurements of laser metal deposited Ti-6Al-4V parts using neutron diffraction

Abstract

Strength of laser deposited parts is in strong dependence on microstructure, residual stresses, size and shape of defects. Knowledge of the residual stress field is crucial for a thorough understanding of the likely subsequent fatigue behaviour and fracture of the part during deposition. Neutron diffraction methods are well established for the study of residual stresses deep inside components. Neutron diffraction has the potential for measurement deep within metallic components. Distribution of residual stress in Ti-6Al-4V wall deposited on the stiff substrate was measured. Finite element simulation was carried out in order to obtain transient and residual inherent stress in the fabricated part. It was shown that peak tensile normal stress exceeds yield stress at the start and end of deposited wall near the substrate. Peak tensile longitudinal stress corresponds to the last deposited layer and lower than yield stress.