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In this paper, the cyclic deformation behavior of an Al-Si-Cu alloy is studied under strain-controlled thermo-mechanical loading. Tests are carried out at temperatures from 20 °C to 440 °C. The effect of strain rate, hold time at temperature and loading sequence are investigated at each temperature. The results show that temperature has a significant effect on the cyclic deformation of Al-Si-Cu alloys. With increasing temperature, the effect of strain rate and hold time become more significant, while load sequence effects remain negligible within the investigated temperature range. Thus, an elasto-viscoplastic model is required for modeling the alloy's behavior at high temperature. This study provides an insight into the necessary information required for modeling of automotive engine components operating at elevated temperature.

The continued rise in specific power output and thermal loading characteristics of the modern automotive diesel engine provides piston engineers and scientists with the challenge of continually improving their knowledge and understanding of thermomechanical loading and durability factors. The capacity to predict thermomechanical fatigue (TMF) effects with confidence at a pre-engineering stage will improve the technology selection and component design processes leading to a more efficient development phase. This paper reviews how the use of advanced instrumented engine testing and finite element modeling (FEM) techniques are helping engineers improve their understanding of transient thermal load regimes in automotive AlSiCuNiMg pistons. The investigations offer insightful observation of transient measured piston temperatures in the high and low frequency operating regimes for two diesel engine platforms.

This paper introduces a new hypereutectic aluminum alloy for piston casting, an improved casting process and a new re-melting procedure. The resulting microstructures improve the fatigue performance of the piston combustion bowl region exposed to severe cyclic thermal and mechanical loading in modern diesel engine applications. It is shown how composition and material properties of the new alloy increase the material's fundamental properties, compared to an existing hypereutectic alloy. The new casting process minimizes the occurrence of fine oxide inclusions which helps to exploit the fundamental material strength. Finally the paper describes the combustion bowl re-melting process and gives engine validation results to illustrate its considerable influence on premature fatigue failure.