Correction of Elastic Anisotropy in Williamson-Hall Plots by Diffraction Young's Modulus and Direct Fitting Method

It is known that the micro-strain in cold worked iron can be evaluated by the classical Williamson-Hall method using the three data of diffraction peaks: {110}, {211} and {220}. It is not clarified that the obtained value gives the true micro-strain or not. In addition, the accuracy of analysis is not so high because the diffraction strength from {220} plane is generally very weak. In this paper, three methods, i.e. classical Williamson-Hall method, Diffraction Young's Modulus Correction method and Direct Fitting method, ware attempted to reconfirm the reasonability of the classical Williamson-Hall method and to estimate accurate values of the parameter alpha and the micro-strain epsilon in the Williamson-Hall equation. The results obtained are as follows: 1) Elastic anisotropy in the Williamson-Hall plots is corrected using the parameter omega which relates to the values of diffraction Young's modulus. 2) The optimal values of parameter omega can be determined by the Direct Fitting method, which can be used to determine the timely orientation-dependent diffraction Young's modulus (E*(hkl)) in cold worked specimens. 3) It was confirmed that the classical Williamson-Hall method can generally give reliable values for the parameter alpha and the micro strain epsilon. 4) No large difference is found for the values of micro-strain epsilon from the three methods. 5) There is a clear linearity between the micro-strain epsilon and yield stress in cold rolled iron specimens.