Chemistry optimisation to improve casting durability of engine blocks

摘要

The research contained herein reviews an alternative Al-Si-Cu alloy that provides the fatigue durability that would be nearly comparable to the 356 or the 319 alloys (having integrated chill), while having comparable or lower associated raw material and processing costs. A total of forty-three V8 engine blocks were produced with an Al-9Si-1Cu alloy, assessed and compared to the production version of the same engine block casting that uses the 319 alloy (Al-7Si-3.5Cu). The casting process used to manufacture the engine blocks was the Cosworth Precision Sand Process. This comparison to the production variant of the V8 engine block includes a detailed microstructure assessment (secondary dendrite arm spacing λ_2, secondary phase distribution/type and porosity), room temperature tensile testing, elevated temperature fatigue staircase plots and hardness measurements. The observation found from the aforementioned analysis was that the Al-9Si-1Cu alloy has lower porosity and, as a consequence, was able to show a 40% increase in the elevated temperature fatigue staircase plot when compared to the same plots made from regular production.