High-cycle fatigue bending strength of rapidly solidified and plastic consolidated RS442 aluminium alloy

Grain refinement in metallic materials down to submicro and nano scale results in improvement of mechanical properties. However, increase in strength under static load is not always accompanied by improved fatigue behaviour. In the current studies microstructure and mechanical properties of the submicrocrystalline RS442 aluminium alloy (chemical composition corresponds to conventional 442 cast alloy) were investigated. The alloy was subjected to rapid solidification followed by the extrusion process (variant 1) and additional annealing at 450 °C (variant 2). Rapidly solidified alloy was also consolidated with addition of graphite (variant 3). As the reference material conventionally cast and extruded alloy was also tested (variant 4). For all material variants strength properties were tested in static tensile test and high-cycle stress-controlled fatigue bending tests. It was found that rapid solidification and plastic consolidations led to increase of static mechanical properties of 442 alloy but reduced its fatigue strength.