Residual Stress and Retained Austenite Testing
Residual Stress Analysis
X-ray diffraction is a well established and accurate method of quantitatively measuring residual stresses in polycrystalline materials - whereby the diffracted X-rays are used to measure very small changes in atomic plane spacing caused by internal residual strains.
The technique can be used to provide valuable information related to the fatigue performance of gears by generating depth profiles, using a combination of chemical etching and electro-polishing methods, to remove successive layers of material.
Retained Austenite Analysis
X-ray diffraction has proved to be the most effective and accurate method of measuring retained austenite levels in steels, particularly for volume fractions of 15% and lower.
The retained austenite content can have a significant effect on the dimensional stability and fatigue life of gears and the amount of retained austenite in ferrite (martensite) can be calculated by comparing the intensity of the diffraction peaks for the two phases.