Secondary aluminum production through the recycling of aluminum chips originating from machining proceedings (e.g. milling, drilling) has occupied the top position among the exploitation procedures of wastes in the last decade. In particular, the solid-state method that replaces the conventional melting and casting stages with a cold pre-compaction stage before the final hot extrusion is a promising new field of interest, taking into account the energy consumption, material loss, processing steps, environmental contamination, cost, etc. The literature results reveal that material produced by the innovative processing route (including cold compaction followed by hot extrusion) is optimum, with very competitive mechanical properties. The present study explores the influence of different heat treatments (no heat treatment, natural aging, artificial aging) on the chip-based hot-extruded aluminum alloy AA6060's fatigue and fatigue corrosion behavior. Experiments were performed on cast-based hot-extruded specimens for comparison reasons. In addition, a detailed microstructural analysis of the micro-morphological fatigue failure features was carried out.

Although the results pointed out the supremacy of cast-based material in the majority of cases of fatigue and fatigue corrosion, the significance of microstructural coherency was highlighted among chip boundaries. Improving the chip bonding quality could lead to a remarkable enhancement in the fatigue life of the recycled chips subjected to hot extrusion and heat-treated processes.