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Profile Fitting in Residual Stress Determination

Published online by Cambridge University Press:  06 March 2019

T. J. Devine  and
J. B. Cohen
T. J. Devine
Affiliation:
Department of Materials Science and Engineering The Technological Institute Northwestern University Evanston, IL 60201
J. B. Cohen
Affiliation:
Department of Materials Science and Engineering The Technological Institute Northwestern University Evanston, IL 60201
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Extract

Of major importance in the determination of residual stress via diffraction is the accuracy of the measurement of the scattering angle (2 θp) of a Bragg peak. This determines the accuracy of the interplanar (d) spacing and hence the strain and stress. In the U.S., the most commonly accepted method of determining peak position is a parabolic fit near the top of a peak. (While a diffraction peak is not parabolic, this is a satisfactory function near the maximum.) The error in this procedure has been derived and tested, and it has been shown that a multipoint fit with a least 7 points is rapid and as precise or more precise than the centroid, the bisector of the half width, or cross correlation, except for sharp peaks in which case the centroid or cross correlation are slightly better. Thus a parabolic fit is generally useful and, since a least-squares fit to this function is readily carried out on modem micro-processors, automatical of a stress measurement is possible, including evaluation of errors.

Type
Research Article
Information
Advances in X-Ray Analysis , Volume 29: Thirty-Fourth Annual Conference on Applications of X-ray Analysis, August 5-9, 1985 , 1985 , pp. 89 - 101
Copyright
Copyright © International Centre for Diffraction Data 1985

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References

1. Thomsen, J. and Yap, F.Y., Effect of Statistical Counting Error on Wavelength Criteria for X-ray Spectra, Res. MBS. 72A: 198(1968).Google Scholar
2. James, M.R. and Cohen, J. B., Study of the Precision of X-ray Stress Analysis, Adv. X-Ray Analysis. 20: 291 (1976).Google Scholar
3. Knuutila, M., “ConputerGontrolledResidual Stress Analysis and Its Application to Carburized Steel”, Dissertation No. 81, Department of Mechanical Eng., Linkoping Univ. Sweden (1982).Google Scholar
4. Wilson, A.J.C., Statistical Variance of Line Profile Parameters, Measures of Intensity, Location and Dispersion, Acta Crystallogr., 23: 888 (1967).Google Scholar
5. James, M.R. and Cohen, J.B., The Application of a Position-Sensitive Xray Detector to the Measurement of Residual Stresses, Adv. X-Ray Analysis. 19: 695 (1976).Google Scholar
6. James, M. and Cohen, J.B., “PARS” - A Fortable X-ray Analyzer for Residual Stresses, Testing and Evaluation, 6: 91 (1978).Google Scholar
7. Mignot, J. and Rcndot, D., Application du Lis sage des Raies de Diffraction des Rayons-X. la Separation du Doublet Kα1, Kα1, J. Appl. Crystallogr, 9: 460 (1976).Google Scholar
8. Hall, M.M., Veeraghavan, V.G., Rubin, H. and Winohell, P.G., The Approximation of Symmetric X-ray Peaks by Pearscn Type VII. istributions, J. Appl. Crystallogr., 10: 66 (1977)Google Scholar
9. Spendley, W., Hext, G.R. and Himsworth, F.B., Sequential Application of Simplex Designs in Optimization and Evolutionary Operation, Technciaetrics, 4: 441 (1962).Google Scholar
10. blelder, J.A. and Mead, R., A Simplex Method for Function Minimization, Ihe computer Jrnl., 7: 308 (1965).Google Scholar
11. Hamilton, W.C., “Statistics in Physical Science”, Ronald Press Co., New York (1964).Google Scholar
12. Devine, T.J., Comparison of Full Profile Peak Finding Methods For Use in X-ray Residual Stress Analysis, Thesis, M.S., Northwestern University (1985).Google Scholar