Residual Stress analysis is carried out as per standard SAE HS 784 “Residual Stress Measurement by X-ray
Diffraction”. The residual stresses are measured by Sin2ψ method, where ψ is the angle of tilt or offset given to the Xray
tube. When a crystal is bombarded with X-rays of a fixed wavelength (similar to spacing of the atomic-scale crystal
lattice planes) and at certain incident angles, intense reflected X-rays are produced when the wavelengths of the
scattered X-rays interfere constructively. When this constructive interference occurs, a diffracted beam of X-rays will
leave the crystal at an angle equal to that of the incident beam. The X-ray beam is used to scan around a fixed angle of
diffraction for a known atomic plane and the inter-planar spacing is measured as per Bragg’s law. The experimental set
up and location for residual stress measurement is given in Fig 4 & 5 respectively.