Influence of the starting microstructure of the AlSi10Mg alloy on the mechanical properties after heat treatment

V svetu kovin so mehanske lastnosti zelo pomembne. Vedno iščemo načine kako jih izboljšati. En od načinov je toplotna obdelava. V diplomskem delu smo obravnavali zlitino AlSi10Mg in kakšne so njene mehanske lastnosti v dveh primerih. Obravnavali smo jo pri višji, 100 K/s in nižji, 5 K/s ohlajevalni hitrosti in nato toplotni obdelavi. Izvedli smo toplotno obdelavo T5 pri kateri je potekalo umetno staranje pri temperaturi 160 °C in času 6 h ter toplotno obdelavo T6 pri kateri je potekalo raztopno žarjenje pri 530 °C in času 6 h, nato pa umetno staranje pri temperaturi 160 °C in času 6 h. Trdote smo izmerili po Metodi Vickers. Tlačne trdnosti pa s tlačnimi preizkusi. Mikrostrukturo pa smo analizirali z metalografsko analizo. Ugotovili smo, da je trdota pri višji ohlajevalni hitrosti v litem stanju višja od trdote pri nižji ohlajevalni hitrosti predvsem zaradi manjših dendritnih zrn in ostalih mikrostrukturnih sestavin v mikrostrukturi. S toplotno obdelavo narašča in je najvišja po toplotni obdelavi T6 pri višji ohlajevalni hitrosti. Tlačna trdnost je tako kot trdota višja pri višji ohlajevalni hitrosti v litem stanju kot pri nižji ohlajevalni hitrosti. Po toplotni obdelavi T5 rahlo pade pri obeh ohlajevalnih hitrostih, a se nato po toplotni obdelavi T6 poveča.In the world of metals, mechanical properties are very important. We are always looking for ways to improve them. One possibility is heat treatment. In this work we have investigated the alloy AlSi10Mg and its mechanical properties in two cases. It was treated with a higher cooling rate of 100 K/s and a lower one of 5 K/s and then heat treated. We performed a T5 heat treatment in which artificial aging took place at a temperature of 160 °C and a duration of 6 hours, and a T6 heat treatment in which solution heat treatment took place at 530 °C and a duration of 6 hours, followed by artificial aging at a temperature of 160 °C and a duration of 6 hours. Hardness was measured using the Vickers method. Compressive strengths were determined by compression tests. The microstructure was examined by metallographic analysis. We found that the hardness at a higher cooling rate in the as-cast state is higher than the hardness at a lower cooling rate, which is mainly due to smaller dendritic grains and other microstructural components in the microstructure. Hardness increases with heat treatment and is highest after T6 heat treatment at a higher cooling rate. Compressive strength in the as-cast state, like hardness, is higher at a higher cooling rate than at a lower cooling rate. After the T5 heat treatment, it decreases slightly at both cooling rates, but then increases after the T6 heat treatment