Residual stress measurements of machined surfaces in Titanium Alloys

Manufacturing processes can result in residual stresses for a wide variety of alloys. In alpha-beta titanium alloys, the development of residual stresses is particularly important because these alloys are often used in narrow tolerance applications. Relaxation of residual stresses during manufacturing and subsequent use may result in unacceptable distortion in parts. However, accurate characterization of residual stresses is challenging. The research presented here considers multiple methods for determining residual stresses in α-β Ti alloy samples subjected to machining experiments. Analytical methods include Rigaku SmartLab XRD using a 1D detector and the sin²ψ method, SmartLab XRD using a 2D detector with the analysis of the Debye Ring, and a Pulstec μ-X360s X-ray analyzer using a 2D cos α method. The dependence of each analytical technique on the grain size, presence of texture, and depth of residual stresses beneath the machined surface are considered in this study. Limitations of these methods is discussed, and the necessity of using a combination of methods to accurately resolve residual stress states in the samples is presented.