The determination of d₀ without a reference material

Abstract

A method for the calculation of a stress free lattice parameter from the analysis of diffraction data from stressed material is discussed, utilising the elastic anisotropy of the material. The technique is demonstrated using the data obtained during a uni-axial tension test on austenitic steel. The uncertainty in the calculated lattice parameter for various choices of a number of diffraction peaks and when different stress levels are available for the calculation is considered. It is shown that when all the data is within the elastic regime, an accurate evaluation of the reference lattice parameter can be made. When some data is in the plastic regime, a more limited evaluation is possible.

Key Words:

• Elastic anisotropy
• Stress free lattice parameter
• Crystallite
• Diffraction peak