Improvement of the heat treatment practice for cylinder heads manufactured from AlSi7MgCu0.5 alloy

Cylinder heads are one of the most complex and overloaded components of internal combustion engines. For this reason, cylinder head alloys must have high thermal conductivity, high temperature and load resistance, and combustion heat to achieve sufficient strength and hardness for processing and installation at room temperature. In addition these features, aluminum is the most suitable material for vehicles that have to lightweight with emission control and fuel saving requirements, and one of the most common aluminum alloy applications are cylinder heads. The use of aluminum casting alloys in cylinder heads saves a significant amount of money with compared to cast iron. The European Aluminum Association has emphasized the importance of heat treatment to improve the characteristics (high strength, high ductility etc.) of aluminum based automotive products. T6 heat treatment is widely used in cylinder head applications. In this study, the solution heat treatment and aging annealing, which are important steps of the standard T6 heat treatment on AlSi7MgCu0.5 alloy V8 cylinder heads, were applied at different temperatures and durations. It is aimed to reduce the heat treatment cycle time for AlSi7MgCu0.5 alloy V8 cylinder heads without sacrificing mechanical properties in operation. As a result, series of heat treatment experiments, the T6 heat treatment process was optimized for solution heat treatment 1 hour at 545 ° C, followed by aging 3 hours at 180 ° C. The mechanical properties of the cylinder heads thus heat treated significantly increased, while the total heat treatment time decreased by 2.5 hours compared to standard heat treatment. This provided a 61% capacity increase and made it possible to undertake a large customer order.