Accession Number : AD0695310

Title :   THE FRACTURING OF STEEL AS A PROCESS OF THE COALESCENCE OF MICROCRACKS,

Corporate Author : FOREIGN TECHNOLOGY DIV WRIGHT-PATTERSON AFB OHIO

Personal Author(s) : Finkel,V. M. ; Zuev,I. B. ; Filatov,A. M. ; Popova,O. S.

Report Date : 17 APR 1969

Pagination or Media Count : 13

Abstract : The phenomenology and mechanism of the process of the merging of microcracks during fracture are investigated in 20 x 60 mm specimens of St.3 low carbon sheet steel 0.3 mm thick. The surface of specimens was prepared as a metallographic section and subsequently the specimen was bent several times until appreciable cracks had appeared; these cracks had to be larger than the grain size of this steel. Subsequently the specimens were fractured by means of a falling weight and the process of fracture was observed with the aid of a micro-filming device. The kinograms thus obtained show a discontinuous propagation of fracture in the carbon steel, with microcracks arising ahead of the main crack and with distinct plastic zones around and ahead of the cracks. As the spaces between cracks diminish to minus 2 mm, the crack trajectories deviate from the line of operation of maximum tensile stresses and subsequently the merger of the plastic zones and hence also of the cracks occurs along the line of operation of maximum tangential stresses. (Author)

Descriptors :   (*CARBON ALLOYS, FRACTURE(MECHANICS)), (*CRACKS, CRACK PROPAGATION), TENSILE PROPERTIES, PLASTIC PROPERTIES, DEFORMATION, LOADS(FORCES), GRAIN STRUCTURES(METALLURGY), GRAIN BOUNDARIES, GRAIN SIZE, USSR

Subject Categories : Metallurgy and Metallography
      Solid State Physics

Distribution Statement : APPROVED FOR PUBLIC RELEASE