Residual Stress Measurement of Titanium Casting Alloy by Neutron Diffraction

Neutron stress measurement can detect strain and stress information in deep region because of large penetration ability of neutron beams. The present paper describes procedure and results in the residual stress measurement of titanium casting alloy by neutron diffraction. In this study, the three axial method using Hooke's equation was employed for neutron stress measurement. This method was applied to the cylindrical shape sample of titanium casting alloy (Ti-6Al-4V). Form the results of this study, this sample has large crystal grain in the inside whole position, it is assumed this large grain was grown up during casting manufacture process. Furthermore, the peak profile used to the stress measurement appears in very weak because of the HCP crystal system of titanium character and effect of large crystal grain. These conditions usually make difficult to measure the accuracy values of residual stresses. Therefore, it had to spend a long time to measure the satisfied data from titanium sample. Regarding to the results of stress measurement, the stress values in the cylindrical sample of three directions is almost same tendency, and residual stresses change from the compressive state in the outer part to the tensile state in the inner part gradually.