ON THE EXISTENCE OF CUBIC IRON-CARBON MARTENSITE.
ILLINOIS INST OF TECH CHICAGO DEPT OF METALLURGICAL ENGINEERING
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AISI 4340 steel bars in the untempered martensitic condition were reduced various amounts up to 10 by drawing. Specimens machined from each bar were examined with x-ray diffraction intensity measurements for two face orientations. It was confirmed that for a specimen face orientation perpendicular to the die drawing direction the integrated intensity increased with increasing deformation. In sharp contrast with this effect, it was found that for a specimen face orientation inclined 45 degrees to the die drawing direction the integrated intensity decreased slightly with increasing deformation. The x-ray intensity data was reconciled by using the model based on the following points a the as-quenched 0.40 carbon martensite is cubic after a very short time at room temperature. b the deformation introduces dislocation networks on active 110 slip planes. c Eshelby locking in the stress fields of the dislocations results in tetragonal martensite regions. d The ordering to form tetragonal martensite causes an increase or decrease in the x-ray diffraction intensity depending upon the orientation of the specimen face being examined. Author
- Metallurgy and Metallography