Effect of prestrain and stacking-fault energy on the application of the Hall-Petch relation in fcc metals and alloys

Journal Article · Tue Jan 01 00:00:00 EST 1980 · Metallography; (United States)

DOI:https://doi.org/10.1016/0026-0800(80)90001-4· OSTI ID:6865857

Wang, S L; Murr, L E

Sheet specimens of nickel, copper, and 70/30 brass, representing a range of stacking-fault free energies of 128, 78, and 14 mJ/m/sup 2/, respectively, were variously annealed to produce a range of four different grain sizes and then cold-rolled to reductions in thickness of 5, 10, 15, 45, and 60%. Plots of the 0.2% offset yield stress as well as the ultimate tensile stress and residual microhardness versus the reciprocal square root of the grain size (D/sup -1///sup 2/) showed that a Hall-Petch-type relationship could be applied in all cases. A plot of the slopes of the Hall-Petch relationships for the annealed materials as a function of the stacking-fault free energy (..gamma../sub SF/ revealed a linear relationship of the form K = (Gb/2..pi..(1 - v)) X (..cap alpha.. - delta..gamma../sub SF/), where ..cap alpha.. and delta are dimensionally consistent constants. For prestrained materials, where the grain microstructure is altered somewhat systematically in the range of stacking-fault free energy as observed directly by transmission electron microscopy, the Hall-Petch relationship becomes delta = delta/sub o/ + ..beta..epsilon/sup 1///sup 2/ - KD/sup -1///sup 2/, where epsilon is the strain, delta/sub o/ is the ''friction stress'' for the annealed material, and ..beta.. is a constant which may be dependent upon the stacking-fault free energy. An equation of this form also applies in the description of the ultimate tensile stress and the hardness except that the additional term accounting for the strain-induced alterations in the microstructure is somewhat altered, and the exponent of this term depends upon the stacking-fault free energy.

• Research Organization: New Mexico Inst. of Mining and Tech., Socorro
• OSTI ID: 6865857
• Journal Information: Metallography; (United States), Vol. 13
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
BRASS
MICROHARDNESS
TENSILE PROPERTIES
COPPER
NICKEL
ANNEALING
GRAIN SIZE
STACKING FAULTS
ALLOYS
COPPER ALLOYS
COPPER BASE ALLOYS
CRYSTAL DEFECTS
CRYSTAL STRUCTURE
ELEMENTS
HARDNESS
HEAT TREATMENTS
MECHANICAL PROPERTIES
METALS
MICROSTRUCTURE
SIZE
TRANSITION ELEMENTS
ZINC ALLOYS
360100* - Metals & Alloys