Serrated flow and work hardening characteristics of Al-5356 alloy

• Published in: Journal of alloys and compounds Vol. 502; no. 1; pp. 139 - 146
• Main Authors: Saad, G., Fayek, S.A., Fawzy, A., Soliman, H.N., Nassr, E.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier B.V 16-07-2010; Elsevier
• Subjects: Alloy development; Aluminum base alloys; Applied sciences; Deformation; Elasticity. Plasticity; Exact sciences and technology; Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology; Metals and alloys; Metals. Metallurgy; Microstructure; Precipitation; Serration; Strain; Strain hardening; Stress-strain relationships; Stresses; VAR; X-ray diffraction; 62.20.Fe; Serration; Metals and alloys; Precipitation; 61.66.Dk; X-ray diffraction; 61.82.Bg; Microstructure; Grain size; Aluminium base alloys; Work hardening; Plastic flow; Stress strain relation; Rupture; Arrhenius equation; Yield strength; Serrated yielding; Strain hardening; Portevin Le Chatelier effect; Strain rate
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2010.04.119

Stress–strain characteristics of Al-5356 are studied. Stress oscillation (repetitive stress drop or serration) in stress–strain relations (jerky flow or the Portevin–Le Chatelier (PLC)) was observed at the temperature ranging from 303 to 373
K at strain rate (S.R.) of 1.5
×
10
−3
s
−1. A relation between the stress reload parameter Δ
σ
R and the strain
ɛ in the jerky flow was found to be in the form [Δ
σ
R
=
A
exp(
ɛ/
α)] with a growth constant
α independent on grain diameter
d and /or deformation temperature
T
w. The effect of grain diameter
d on the work-hardening parameters (WHP) yield stress
σ
y, fracture stress
σ
f, total strain
ɛ
T, work-hardening coefficient
χ
p(=d
σ
2/d
ɛ) and the strain-hardening exponent
n(=d
ln
σ/d
ln
ɛ) of Al-5356 alloy were evaluated at the applied deformation temperature range. The grain diameter
d and deformation temperature
T
w significantly decreased the total strain
ɛ
T, the yield stress
σ
y and the fracture stress
σ
f of the tested samples, while the strain-hardening exponent
n changed slightly. The relationship between the yield stress
σ
y of the alloy under investigation and temperature follows an Arrhenius law. The mean activation energy of the deformation process was found to be ∼87
kJ/mole, close to the activation energy of grain boundary diffusion in aluminum alloy.