The variation of subgrain misorientation in aluminum deformed to large steady-state creep strains

Conference · Mon Nov 17 04:00:00 EST 1986

OSTI ID:6986394

Kassner, M E; McMahon, M E

Pure aluminum was deformed in torsion of 644/sup 0/K to various steady-state strains up to 16.33. The character of the subgrain boundaries changes dramatically over steady state. As the torsion specimens are twisted, the original grains of the annealed aluminum spiral around the torsion axis and the axial width of the grains is reduced. The average misorientation angle of the low-angle boundaries is about 0.5/sup 0/ at onset of steady state (epsilon = 0.20). This increases by over a factor of 2 during steady state before reaching saturation at 1.2/sup 0/ at 1.2 strain. All this suggests that the details of the subgrain boundaries are not an important consideration in the rate-controlling process for creep. At the onset of steady state essentially all of the subgrain boundaries have small misorientation angles. If we replace one-third of these boundaries with high-angle boundaries (average misorientation of about 25/sup 0/) and double the average misorientation of the remaining two-thirds, the flow stress is nearly unchanged. Results suggest that a description of the rate-controlling process for creep should consider the density of dislocations not associated with subgrain boundaries.

• Research Organization: Lawrence Livermore National Lab., CA (USA); Naval Postgraduate School, Monterey, CA (USA)
• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 6986394
• Report Number(s): UCRL-94747; CONF-870447-1; ON: DE87003238
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360103* -- Metals & Alloys-- Mechanical Properties
ALUMINIUM
CREEP
CRYSTAL DEFECTS
CRYSTAL STRUCTURE
DEFORMATION
DISLOCATIONS
ELEMENTS
GRAIN BOUNDARIES
HIGH TEMPERATURE
LINE DEFECTS
MECHANICAL PROPERTIES
METALS
MICROSTRUCTURE