Accession Number : AD0486444

Title :   ON THE MICRO-MECHANISM OF SECOND-ORDER EXTENSION OF ALUMINUM IN REVERSED CYCLIC TORSION.

Descriptive Note : Technical rept.,

Corporate Author : COLUMBIA UNIV NEW YORK INST FOR THE STUDY OF FATIGUE AND RELIABILITY

Personal Author(s) : Ronay, Maria

Report Date : MAY 1966

Pagination or Media Count : 21

Abstract : Superpure aluminum specimens extended by unidirectional straining, by the second-order effect in cyclic torsion, and by a combination of the two were studied by means of X-ray diffraction optical microscopy, tensile tests and surface-contour observation. Specimens deformed by the second-order effect show a sub-grain formation and a permanent displacement on these slip planes seen on the surface. These permanent displacements in the radial direction of the specimen are in the average in quadratic relation with the torsion amplitude applied, a relation in agreement with the theory of second-order effects. It is believed that accumulation of unidirectional strain increments occurs when slip movements during inelastic strain amplitudes do not fully reverse and when the irreversible slip governed by second-order forces produces small unidirectional displacements in each half cycle. (Author)

Descriptors :   *CREEP), (*ALUMINUM, (*TORQUE), TENSILE PROPERTIES, STRESSES, DEFORMATION, STRAIN(MECHANICS), CRYSTAL DEFECTS, FRACTURE(MECHANICS), X RAY DIFFRACTION, MICROSTRUCTURE, FATIGUE(MECHANICS), GRAIN STRUCTURES(METALLURGY).

Subject Categories : Properties of Metals and Alloys

Distribution Statement : APPROVED FOR PUBLIC RELEASE