The grain refiners used in the casting of aluminium alloys

Due to its low density, high plasticity, high conductivity and its abundance in nature, pure aluminium is commonly preferred in industry. However, its uses are restricted as it has a coarse grained microstructure and relatively low mechanical properties. It?s essential that these drawbacks are eliminated through alloying or grain refinement. Grain refinement process has become an ordinary step in the casting process of aluminium alloys. The purpose of this process is to enable heterogeneous nucleation by making additions to the melt. Additional nucleant leads to a smaller grain size. The main principle in this is that the nucleant agents in the melt prevent the growth of the grains enabling the solidification in different points and they promote the formation of equiaxed small grains. Notwithstanding that various master alloys are used in the grain refinement practices of aluminium alloys, the most popular and efficient one is the Al-5Ti-1B alloy. The TiAl3 and TiB2 phases in the microstructure of this alloy act as heterogeneous nucleant points and enable the nucleation. The grain refinement efficiency of the master alloy pertains to the size distribution and morphology of these phases.In this study, Al-5Ti-1B grain refiners were produced through the addition of K2TiF6 and KBF4 salts to commercial purity aluminium. Subsequently, the effects of the changes made in the parameters during the melting, alloying and casting process and the effects of additional practices related to forming after the casting process to the grain refinement performance of the end product were analyzed. The grain refining performances were compared after adding the Al-5Ti-1B grain refiners to commercial purity aluminium (AA 1050). Accordingly, the effects of the parameters taking place during the production were examined and it was aimed to optimize the production and to enhance the grain refinement performance by additional processes applied to the end product.