Cyclic Stress-Strain Behavior and Low Cycle Fatigue Life of AA6061 Aluminum Alloy

AA6061 alloy is one of the most widely used aluminum alloy in modern aerospace and automotive industries due to low cost, good formability and high specific strength. Most of aluminum structural components experience dynamic loading, which leads to fatigue failure. Since studies on the strain-controlled fatigue behavior of these alloys are very limited, this study was aimed to evaluate the strain-controlled cyclic deformation behavior of an extruded 6061 aluminum alloy and determine the fatigue life under varying higher strain amplitudes. The stress-strain responses exhibited essentially symmetric responses with slight Bauschinger effect. A slight cyclic hardening occurred at high strain amplitudes (0.8–1.2%) within the first ten cycles, and then cyclic stabilization follows until failure. It had longer fatigue life which can also be described by the Coffin–Manson law and Basquin’s equation. Crack initiated from the specimen surface and crack propagation was characterized by fatigue striation-like features at lower strain amplitudes.