Accession Number : AD0719832

Title :   Effect of Microcracks on the Brittle Fracture of Mild Steel,

Corporate Author : FOREIGN TECHNOLOGY DIV WRIGHT-PATTERSON AFB OHIO

Personal Author(s) : Sobepanek,T.

Report Date : 04 DEC 1970

Pagination or Media Count : 20

Abstract : Iron (C 0.044, Mn 0.04, Cr 0.09, O 0.076, and N 0.013 wt. per cent) was subjected to various plastic deformations. Microscopic observations showed that the distribution of microcracks as well as the structure of the metal depended on the history of plastic deformation. Upsetting caused the formation of a much larger amt. of horizontal microcracks (perpendicular to the axis) which caused a loss of strength. It is probable that a metal subjected to plastic deformation and thereafter loaded to brittle fracture had 2 opposing effects acting on it: (1) a hardening effect and (2) the effect of microcracks and intrinsic stresses. The 1st effect depends only on the deformation degree, and does not depend on the form of plastic deformation. However, the 2nd effect depends on deformation degree, form of deformation, as well as on the kind of load applied during the deformation. The macro- and microscopic observations showed that on brittle fracture, the principal factors which affect the resistance of soft steel are the amt. and form of the microcracks and other defects, as well as the orientation of the microcracks and intrinsic stresses. (Author)

Descriptors :   (*STEEL, FRACTURE(MECHANICS)), BRITTLENESS, DEFORMATION, CRACKS, STRESSES, USSR

Subject Categories : Metallurgy and Metallography

Distribution Statement : APPROVED FOR PUBLIC RELEASE