Accession Number : AD0651991

Title :   ON THE EXISTENCE OF CUBIC IRON-CARBON MARTENSITE.

Descriptive Note : Technical rept.,

Corporate Author : ILLINOIS INST OF TECH CHICAGO DEPT OF METALLURGICAL ENGINEERING

Personal Author(s) : Breyer,N. N. ; Nachtman,E. S.

Report Date : DEC 1966

Pagination or Media Count : 27

Abstract : 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)

Descriptors :   (*MARTENSITE, STEEL), X RAY DIFFRACTION, CARBON, GRAIN STRUCTURES(METALLURGY), DISLOCATIONS

Subject Categories : Metallurgy and Metallography

Distribution Statement : APPROVED FOR PUBLIC RELEASE