INFLUENCE OF TEMPERATURE ON CYCLIC STRESS-RESPONSE AND FRACTURE-BEHAVIOR OF ALUMINUM-ALLOY-6061

The cyclic stress response and fracture characteristics of aluminum al loy 6061 was studied at different temperatures. The specimens were cyc lically 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 t o dislocation movement, thereby causing a progressive loss of strength ening 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 initiat ion and subsequent crack propagation. The fracture behavior of the all oy is discussed in terms of competing influences of intrinsic microstr uctural effects, deformation characteristics arising from a combinatio n of mechanical and microstructural contributions, plastic strain ampl itude and concomitant response stress, and test temperature. (C) 1997 Elsevier Science Ltd. All rights reserved.