Accession Number : AD0822153

Title :   DEFORMATION PROCESSING OF ANISOTROPIC METALS.

Descriptive Note : Final rept. 1 Jul 66-30 Jun 67,

Corporate Author : MASSACHUSETTS INST OF TECH CAMBRIDGE METALS PROCESSING LAB

Personal Author(s) : Backofen, W. A. ; Azzarto, F. J. ; Murty, G. S. ; Zehr, S. W.

Report Date : SEP 1967

Pagination or Media Count : 68

Abstract : A study of the mechanical behavior of the magnesium alloy, Mg ZK60, and its associated microstructural changes has added to the theoretical understanding and the possibility of engineering application of superplasticity. A strongly developed Bingham-type behavior at low strain rates has been interpreted as a result of a parallel operation of diffusional creep and grain-boundary shear, with the low strain-rate sensitivity of flow stress being derived from unusually high and rate-insensitive boundary-shear resistance. Evidence for the diffusional creep contribution comes primarily from electron microscopy of strained surfaces. Characteristic striated bands are associated with such deformation and have been shown to correlate with the 'denuded' zones that have been independently related to diffusion creep in Mg-1/2 wt % Zr alloy. Implications relative to upper and lower strain-rate bounds on superplastic forming are pointed out.

Descriptors :   *ANISOTROPY), (*ALLOYS, (*STRAIN HARDENING, ALLOYS), (*MAGNESIUM ALLOYS, DUCTILITY), EXTRUSION, ELONGATION, PLASTIC PROPERTIES, GRAIN SIZE, CREEP, STRESSES, MICROSTRUCTURE.

Subject Categories : Properties of Metals and Alloys

Distribution Statement : APPROVED FOR PUBLIC RELEASE