Studying the measurement by X-ray diffraction of residual stresses in Ti6Al4V titanium alloy

A study is conducted into the measurement by X-ray diffraction of residual stresses in Ti6Al4V. This measurement method is now widely used but its possibilities and limits when applied to titanium alloy are poorly defined, especially as far as measurement accuracy and reliability are concerned. Experimental set-ups for tensile and compression stresses were developed. These assemblies and the measuring system were validated on a reference test coupon of 316 L steel. Test campaigns highlighted the difficulties encountered with this method when applied to Ti6Al4V. Repeatability, the influence of the load and the measuring system parameters as also material constants on experimental measurements are explored. Finally, a method to calculate the offset ratio between the stress measured and the theoretical stress is proposed.