Influence of temperature on cyclic stress response and fracture behavior of aluminum alloy 6061

Abstract

The cyclic stress response and fracture characteristics of aluminum alloy 6061 was studied at different temperatures. The specimens were cyclically deformed using tension-compression loading under total strain-amplitude control. The alloy showed evidence of softening at all test temperatures. The degree of cyclic softening was observed to increase with an increase in test temperature. The presence of shearable matrix precipitates in the alloy results in a local decrease in resistance to dislocation movement, thereby causing a progressive loss of strengthening contribution. At the elevated temperatures, localized oxidation and embrittlement at the grain boundaries are promoted by the applied cyclic stress and play an important role in accelerating crack initiation and subsequent crack propagation. The fracture behavior of the alloy is discussed in terms of competing influences of intrinsic microstructural effects, deformation characteristics arising from a combination of mechanical and microstructural contributions, plastic strain amplitude and concomitant response stress, and test temperature.