When using x-ray diffraction to measure residual stress, we measure the strain in the crystal lattice and then calculate the residual stress based on the assumption of a linear elastic distortion.

To determine the stress, we must measure the strain for at least two known orientations relative to the sample surface. This technique works best for crystalline materials that are fine-grained and produce diffraction for any surface orientation.

Although X-Ray diffraction method commonly used for surface residual stresses, it is also possible to obtain a residual stress profile along the depth by removing the layer from the surface by electropolishing.

Advantages:

The technique has several advantages, including being non-destructive (only for surface measurement), allowing for measurements in the lab or on-site, measuring multi-axial residual stress state.

Disadvantages:

However, there are also disadvantages, such as limited measurement depths, only being applicable to polycrystalline materials, being affected by grain size and texture, and requiring a good component surface finish.