Impact of Various Types of Heat Treatment on Mechanical Properties of the EN AC-AlSi6Cu4 Alloy

The Al-Si-Cu alloys with content of the copper from 2 to 4 percent, after solutioning and artificial ageing treatments (T6 heat treatment), feature high strength and very high hardness, however their elongation is considerably reduced. Maintaining value of elongation on the level of initial alloy is possible due to homogenizing treatment performed prior the T6 treatment. Performed strength tests of the initial alloy and the alloy after individual types of the heat treatment enable comparison of obtained results and assessment of usability of the investigated alloy to production of a castings. Test pieces to the strength tests were poured in standardized metal moulds. Parameters of the heat treatment, temperature and duration of heating were established on base of the literature and the ATD diagram performed for the investigated alloy. Investigated EN AC-AlSi6Cu4 alloy after homogenizing treatment becomes plastic, its elongation A₅ and its impact strength KC increase nearly three times, with slight decrease of the tensile strength R_m. Dispersion hardening in connection with the homogenizing treatment results in increase of the tensile strength R_m with 68%, hardness and impact strength with 40% with elongation at level of the alloy without heat treatment. Making suitable selection of various types of the heat treatment it is possible, depending on needs, to control mechanical properties of the alloy.