Influence of Heat Treatment on Fatigue Behavior of Aluminum Silicon Carbide Graphite Hybrid Composite

摘要

Aluminum silicon carbide graphite hybrid composite finds automotive and aerospace applications because of its tailor made improved hardness and solid lubrication properties. Present work aims at investigating the effect of ageing heat treatment on fatigue behavior of aluminum hybrid composite. Aluminum silicon carbide graphite hybrid composite specimens were fabricated by stir casting method. Ageing heat treatment on hybrid composite fatigue specimens was carried out using muffle furnace at ageing temperatures 170° and 270℃. Three stress level fatigue tests were conducted on as-cast and ageing heat treated hybrid composite specimens using rotating beam fatigue testing machine. Stress life (S-N) and reliability stress life (R-S-N) curves for as cast and ageing heat treated hybrid composite specimens were established. Comparison of stress life curves of as-cast hybrid composite with age heat treated hybrid composite at 170℃ reveals that ageing heat treatment enhances the fatigue behavior of hybrid composite. Significant changes in microstructure and precipitation of second phase particles attributes to superior fatigue resistance of age heat treated hybrid composite. Fatigue behavior of age heat treated hybrid composite at 270℃ was found to be inferior to as-cast hybrid composite. Dendritic microstructure formation which occurs due to over ageing results in reduced fatigue resistance of the hybrid composite.