Micromechanics of shear banding

Conference · Sat Aug 01 00:00:00 EDT 1992

OSTI ID:6924344

Gilman, J J

Shear-banding is one of many instabilities observed during the plastic flow of solids. It is a consequence of the dislocation mechanism which makes plastic flow fundamentally inhomogeneous, and is exacerbated by local adiabatic heating. Dislocation lines tend to be clustered on sets of neighboring glide planes because they are heterogeneously generated; especially through the Koehler multiple-cross-glide mechanism. Factors that influence their mobilities also play a role. Strain-hardening decreases the mobilities within shear bands thereby tending to spread (delocalize) them. Strain-softening has the inverse effect. This paper reviews the micro-mechanisms of these phenomena. It will be shown that heat production is also a consequence of the heterogeneous nature of the microscopic flow, and that dislocation dipoles play an important role. They are often not directly observable, but their presence may be inferred from changes in thermal conductivity. It is argued that after deformation at low temperatures dipoles are distributed a la Pareto so there are many more small than large ones. Instability at upper yield point, the shapes of shear-band fronts, and mechanism of heat generation are also considered. It is shown that strain-rate acceleration plays a more important role than strain-rate itself in adiabatic instability.

• Research Organization: Lawrence Berkeley Lab., CA (United States)
• Sponsoring Organization: USDOE; USDOE, Washington, DC (United States)
• DOE Contract Number: AC03-76SF00098
• OSTI ID: 6924344
• Report Number(s): LBL-32810; CONF-9209240-3; ON: DE93002568
• Resource Relation: Conference: Society of Engineering Science (SES) technical meeting, San Diego, CA (United States), 14-16 Sep 1992
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
DISLOCATIONS
ANNIHILATION
DIPOLES
PLASTICITY
SHEAR
HEATING
INSTABILITY
SOLIDS
STRAIN HARDENING
STRAIN RATE
BASIC INTERACTIONS
CRYSTAL DEFECTS
CRYSTAL STRUCTURE
ELECTROMAGNETIC INTERACTIONS
HARDENING
INTERACTIONS
LINE DEFECTS
MECHANICAL PROPERTIES
MULTIPOLES
PARTICLE INTERACTIONS
360103* - Metals & Alloys- Mechanical Properties
665000 - Physics of Condensed Matter- (1992-)