Abstract
The contribution of grain size and precipitation hardening to the yield stress and other mechanical properties was investigated. An alloy of iron with 1 % copper was prepared as supersaturated solid solution with grain sizes between 12 and 140 μm. By ageingat 500 and 600° C different precipitation hardening conditions were produced.
For small particle sizes an additive behaviour of grain-boundary and precipitation hardening was found (particle radiusr < 50 Å). For large particle sizes the yield stress is independent of grain size (r > 150 Å). A transition is found for intermediate particle sizes with grain size dependence for small and independence for large grain sizes (50 Å <r < 150 Å).
The effect of grain boundaries and particles on the formation and motion of dislocations is used to explain this behaviour.
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Abbreviations
- σy :
-
measured yield stress
- Δσ :
-
increase in yield stress
- Δσ p :
-
particle hardening
- Δσ b :
-
grain-boundary hardening
- δσ s :
-
solid solution hardening
- σ α-Fe:
-
yield stress of a pure α-Fe crystal
- σ 0 :
-
yield stress of the alloy atD −1/2=0≡ D=∞
- D :
-
grain size
- k y :
-
slope of Hall-Petch-relation
- b :
-
Burgers vector
- ε :
-
plastic strain
- ρ y :
-
dislocation density at 0.2 % strain
- ρ b :
-
density of dislocation generated at grain boundaries
- ρ s :
-
dislocation density from second sources
- ρ p :
-
density of dislocations generated at particles
- λ :
-
average free path of dislocation
- G :
-
shear modulus
- α:
-
constant factor relatingΔσ andρ
- σu :
-
ultimate tensile strength
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Hornbogen, E., Staniek, G. Grain-size dependence of the mechanical properties of an age-hardening Fe-1 % Cu-alloy. J Mater Sci 9, 879–886 (1974). https://doi.org/10.1007/BF00570379
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DOI: https://doi.org/10.1007/BF00570379