The grain refining process is one of the main practices of casthouses when casting aluminium alloys, which reduces the size of α-Al crystal grains. The reduction of α-Al crystal grains is takes place in different way, of which the most common practice is adding master alloys or grain refiners of type Al-Ti-B into the melt. The aim of the master thesis was to find a way to check the effectiveness of grain refiners in a simple and at the same time reliable way.
With the appropriate addition of grain refiners, in our case AlTi3B1, seeds are introduced into the melt for heterogeneous nucleation of primary α-Al crystal grains. The quality and efficiency of delivered grain refiners, which may vary from delivery to delivery, are very important to ensure an adequate α-Al crystal grain size below 200 µm. In the literature, we can find the standard method TP1 for determining the efficiency of the grain refiners, but it is demanding for industrial applications. Therefore, the goal was to develop a simple method for determining the effectiveness of grain refiners to be used in regular quality inspections of grain refiners in an industrial environment. We have developed a method where primary aluminium is cast with the appropriate addition of grain refiners into a steel "ring" which is placed on a fireproof insulating material. After solidification, a microstructural grain analysis is performed in accordance with the ASTM 112-96 standard. In parallel, the standard TP1 method was also performed for the same amount of added grain refiners to the primary aluminium. Thus, we have obtained a link between our method and the standard method for determining the efficiency of the grain refiners, with which we will be able to compare the efficiency of the supplied grain refiners.
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