Accession Number : AD0704789

Title :   FATIGUE CRACK INITIATION AS VIEWED BY SCANNING ELECTRON MICROSCOPY.

Descriptive Note : Technical rept.,

Corporate Author : GEORGE WASHINGTON UNIV WASHINGTON D C INST FOR THE STUDY OF FATIGUE FRACTURE AND STRUCTURAL RELIABILITY

Personal Author(s) : Wood,William A.

Report Date : JAN 1970

Pagination or Media Count : 17

Abstract : It is pointed out that high internal stress, commonly regarded as necessary for initiating fracture by unidirectional deformation of a metal, does not seem essential to crack initiation by cyclic deformation of fatigue. An alternative whereby fatigue cracking can be started simply by the geometry of slip movement is generalized. The hypothesis was tested by the recently developed scanning electron-microscope for copper and aluminum specimens subjected to large amplitudes of cyclic strain (torsion), which gives a generalized type of slip movement. This technique in broadly confirming the hypothesis brings out striking forms of initial fatigue damage. (Author)

Descriptors :   (*FRACTURE(MECHANICS), *ELECTRON MICROSCOPY), COPPER, ALUMINUM, CRACKS, DEFORMATION

Subject Categories : Metallurgy and Metallography

Distribution Statement : APPROVED FOR PUBLIC RELEASE