Constitutive modeling of a 5182 aluminum as a function of strain rate and temperature
- Los Alamos National Lab., NM (United States)
- Alcan International Ltd., Kingston, Ontario (Canada)
- Univ. of Illinois, Urbana, IL (United States). Dept. of Mechanical and Industrial Engineering
The authors have measured the stress/strain response of a 5182 aluminum alloy as a function of strain rate and temperature. As expected at room temperature and quasi-static strain rate this alloy exhibits dynamic strain aging with negative strain-rate sensitivity. At higher temperature, they have separated the response into two categories, when the material displays a yield drop and when it does not. The yield drop was only observed if the yield stress was below 70 MPa. In this case the work-hardening curve was for practical purposes flat. Within this regime the deformation has been labeled Class A behavior. It occurs by continuous motion of dislocations accompanied by diffusion of solute. It is further shown that a constitutive relation such as {dot {var_epsilon}} = A({sigma}/{mu}){sup n} {center_dot} {mu}b{sup 3}/kT {center_dot} exp({minus}Q{sub D}/kT) is appropriate to describe deformation in this temperature/strain-rate regime where the solute drag mechanism dominates. In this expression Q{sub D} is the activation enthalpy for self diffusion of Mg in aluminum, which is 131 kJ/mol. In the high-stress regime, where the yield stress is above 80MPa, there is positive work hardening associated with flow stress behavior of the 5182 alloy. The yield stress was nearly constant; however, the hardening and saturation flow stress increases with decreasing temperature and increasing strain rate. In this regime the deformation is dominated by dislocation accumulation and dynamic recovery. The authors have found that the Mechanical Threshold Strength (MTS) model accurately describes the constitutive response as a function of temperature and strain rate.
- Research Organization:
- Los Alamos National Lab., NM (United States)
- Sponsoring Organization:
- USDOE Office of Energy Research, Washington, DC (United States)
- DOE Contract Number:
- W-7405-ENG-36
- OSTI ID:
- 307983
- Report Number(s):
- LA-UR--98-2731; CONF-981054--; ON: DE99001653
- Country of Publication:
- United States
- Language:
- English
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