A Comparative Study of Constitutive Characteristics and Microstructure Evolution between Uniaxial and Plane Strain Compression of an AA6061 Alloy

摘要

The hot deformation behavior of an AA6061 alloy was comparatively studied by uniaxial compression (UC) and plane strain compression (PSC) in the temperature range of 300-450 degrees C and strain rate range of 0.01-5s(-1). The processing maps were constructed based on a dynamic materials model, and the associated microstructures were observed. Under the same deformation conditions, the flow stress of the AA6061 alloy during PSC is higher than that during UC, which can be characterized by the Zener-Hollomon (Z) parameter in a hyperbolic sine-type equation with an activation energy Q of 175.2kJmol(-1) and 201.9kJmol(-1), respectively. In addition, the instability domain is narrower under PSC compared to that under UC. The observed microstructures also indicate that as the Z value decreases, the tendency of dynamic recrystallization increases during PSC. The softening mechanisms in the AA6061 alloy after PSC and UC mainly consist of the dynamic recovery that is accompanied by a slight dynamic recrystallization. The optimum parameters are in the temperature range of 360-450 degrees C and strain rate range of 0.03-0.3s(-1) for UC, and for PSC, the optimum parameters are in the temperature range of 320-400 degrees C and strain rate range of 0.01-0.05s(-1).