IRON AND STEEL APPLICATIONS 



MATERIAL FOR EXAMINATION 



SPECTROGRAPHIC 

 &/OR CHEMICAL 

 ANALYSIS 



SUPPLEMENTARY 

 X-RAY DIFFRACTION 

 ANALYSIS OF THIN 

 SECTION 



INTER- RELATION OF METHODS FOR THE 

 INVESTIGATION OF MATERIALS. 



Fig. 1 



MICROSEGREGATION 



size, distribution and shape. The use of x-ray 

 diffraction analysis of the same thin section 

 may be valuable in establishing the identity 

 of phases in a particular region, "pin- 

 pointed" if necessary by reference to some 

 fiducial marks on the specimen. Such pat- 

 terns have been used for the identification 

 of phases which have a characteristic appear- 

 ance on the microradiograph (3) or under 

 the microscope. When the identification of 

 typical localized features is once established 

 the microradiograph alone may then be suffi- 

 cient for subsequent identification. Microra- 

 diography is also directly useful in revealing 

 micro-segregation within grains or passing 

 through grains, and may assist in the iden- 

 tification of inclusions as well as metallur- 

 gical phases (See next article). 



The comparatively new technique of mi- 

 crobeam analysis (4, 5, 6) has a special place 

 in such a scheme because it gives information 

 about the chemical constitution in a small 

 region and can therefore point to, or confirm, 

 the identity of phases and indicate micro- 

 segregation. The technique does in fact em- 

 ploy spectrographic analysis of x-rays 

 emitted from the small region referred to, 

 the excitation being provided by an electron 

 beam. 



REFERENCES 



1. Andrews, K. W. and Johnson, W., "X-ray 



Microscopy and Micro-radiography," pp. 

 581-9, 1957, Academic Press, New York. 

 (Edited by V. E. Cosslett, A. Engstrom and 

 H. H. Pattee, Jr.). 



2. Johnson, W. and Andrews, K. W., Iron and 



Steel, 31, 437-444 (1958). 



3. McBriar, E. Maud, Johnson, W., Andrews, 



K. W., AND Davies, W., /. Iron and Steel 

 7ns<., 177, 316 (1954). 



4. Castaing, R. AND Descamps, J., /. Phys. 



Radium, 16, 304-317 (1955). 



5. Philibert, J. AND Crussard, C, /. Iron and 



Steel Inst., 183, 42-47 (1956). 



6. Melford, D. a. and Duncvmb, P., Metallur- 



gia, 57, 159-161 (1958). 

 (See also chapter by P. Duncumb pp. 617-622 

 of the same volume as Reference (1) above.) 



K. W. Andrews 



IRON AND STEEL APPLICATIONS OF 

 MICRORADIOGRAPHY 



The application of microradiograph}^ to 

 iron and steel does not usually involve seri- 

 ous difficulties in specimen preparation al- 

 though cracking due to brittleness can occur, 

 and specimens of the necessary thinness do 

 in fact tend to curve slightly (1). A thick- 

 ness of 0.002 inch has been found most satis- 



587 



