Strain concentration degree defining ductility and catastrophic failure of 6061 aluminum alloy

Abstract

The physical control of ductile deformation and failure behaviors of aluminum alloys is still open to investigation, although this is a central problem for material design and safety evaluation. In this study, 6061 aluminum alloy sheets with different pre-cut depths were uniaxially stretched, and the evolution of strain fields was monitored to reveal the relationship between the strain concentration and failure process. The average strain/strain fluctuation ratio and the strain propagation velocity were defined to quantify the strain concentration degree. The strain concentration degree is an intrinsic factor hosting deformation ductility, maximum bearing load, and failure modes. The underlying mechanism of this changing ductility and failure process is the increased strain/stress concentration degree due to increased pre-cut depth. The experimental results indicated that higher ductility resulted in a larger catastrophic failure in the 6061 aluminum alloy. A lower deformation ductility led to a more gradual macroscopic failure. Our findings suggest that various origins inducing different strain concentration degrees can cause various effects on ductility and failure modes of 6061 aluminum alloy.