In this research thermal analysis was carried out for different alloys which use for gravity die cast cylinder heads. The experiments were implemented under industrial conditions. The aim was to examine the effect of the small amount of supplementary grain refining pre-alloy on primary crystallization for hot-crackings. Different evaluating methods of thermal analysis were tested and compared. Results proved that the dosing small amount of grain refining alloy is favorable in the foundry production practice.

High pressure die casting (HPDC) is a manufacturing process for producing accurately dimensioned, sharply defined, smooth or textured surface metal parts. It is accomplished by injecting liquid metal at fast velocity and under high pressure into reusable steel dies. Compared to other casting processes, die casting is at the top end of both velocity and pressure. The high velocity translates into a very turbulent flow condition. The process is often described as the shortest distance between raw material and the finished product.

Grain refining is an important technological step for the nucleus growth of the melt, in order to increase the number of nuclei, to improve mechanical properties (tensile strength, yield strength, hardness, elongation), feeding conditions and to decrease the tendency of hot tearing and the degree of sintering. [1][2] The aim of the experiments was the determination of the grain refining effects of titanium (Ti) addition in the form of AlTi5B1 master alloy to the examined alloys (AlSi7MgCu0.5 – AC 42 000, AlSi9Cu3Fe0.5 – 46 500; AlSi9Cu1 – AC 46 400). The results prove that the addition of small amount of master alloy has a favourable effect on the foundry practice.

The aim of the experiments with various Al-Si alloys was to examine how different experimental conditions affect the inclusion content of the molten alloys. The utilisation of two cleaning salts from different manufacturers were examined during degassing treatment, in case of AlSi7MgCu0.5 alloy. In order to determine the degree of purity, K-mould test were carried out and evaluated. To acquire more realistic results, several test bars were prepared for each technological step. Beside K-moulds, test bars for density index (Dichte-index) measurement were also casted, to determine the dissolved hydrogen content of the melt.

Kutatómunkánk során különböző Al-Si