Internal Friction in Extruded Aluminium Alloy

Abstract

Aluminium alloys have very useful properties. Because they are light, easily formed, machined and cast, they are widely used in aircraft industry and automotive industry. Their mechanical properties are mostly influenced by former mechanical and thermal treatment. An extruded aluminium alloy EN AW – 2007 was used in the as-received state and the specimens were thermally cycled with increasing the upper temperature step-by-step. After each thermal cycle the stress-amplitude dependence of internal friction was measured at room temperature. The quality factor Q-1was measured by a resonant method at a frequency of 20 kHz. Thermal and mechanical treatments influenced the anelastic properties of the material. The thermal treatment affects the internal friction in a positive way, while the mechanical treatment decreases Q-1. The microstructural changes were observed by optical microscopy.