Thixoextrusion of an A356 alloy: microstructural studies and high temperature fatigue behaviour

Isothermal tensile, isothermal and thermomechanical fatigue tests were conducted on thixoextruded and permanent mould cast A356 T6 aluminium alloy over a broad range of temperatures. The results revealed a significant decrease in strength parameters at 280 °C, for both materials. The fatigue lives of thixoextruded material were substantially higher than those of permanent mould cast samples under isothermal and thermomechanical fatigue loading. At corresponding mechanical and inelastic strain ranges, thermomechanical out-of-phase cycling were higher than in-phase cycling for the alloy. Due to data scatter, the out-of-phase fatigue lives of the permanent mould cast samples and of the thixoextruded samples appeared to be very similar.