In order to determine the type and size of the residual stress in the initial and deformed state we applied X-ray diffraction. Stress and texture measurement were done on the lateral surface of the pipe, but due to geometrical conditions, the most reliable result of the stress values were obtained for the position of the tube axis in the plane of diffraction. The difficulty in the analysis of deformation by sin Ψ ² proved to be varied by texture in both samples. Diffraction elastic constants for both samples were calculated on the basis of the orientation distribution functions. Residual stresses were calculated based on the assumptions of the Reuss model.
We derived the full form of the tensor of plastic and stiffness and elastic constants has been developed based on these models in order to enable the transformation tensor by rotation in accordance with the Einstein summation convention. In order to confirm the validity of these operations Young's surface was calculated , which is a spatial graph of the inverse element of S3333 stiffness tensor in orientation of the unit cell of the crystal.