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Magnezijeve zlitine za gnetenje so zaradi nizke specifične gostote zanimive za uporabo v avtomobilski industriji. Za te izdelke je pomembna visoka trajna dinamična trdnost, to lahko izboljšamo z mehanskim utrjevanjem površine. Eden od možnih postopkov je kavitacijsko utrjevanje. V magistrskem delu smo določili vpliv parametrov kavitacijskega utrjevanja magnezijeve zlitine AZ80, ki ima 8,5 % Al in 0,5 % Zn (masni delež). Zlitina je bila v topilno žarjenem stanju (24 h pri 420 °C) in v staranem stanju (dodatno 8 h pri 250 °C). Vzorce smo utrjevali z različnimi intenzitetami obdelave, ki so se povečevale od 1 s/mm do 20 s/mm. Vrednotili smo naslednje lastnosti: mikrotrdoto, zaostale napetosti, hrapavost, korozijsko odpornost in mikrostrukturo. Vrednosti meritev smo primerjali z osnovnim materialom, tako smo lahko določili globino modificiranega površinskega sloja. Opazovali smo tudi prisotnost erozije materiala in nastanka razpok pri večjih intenzitetah kavitacijskega utrjevanja. Wrought magnesium alloys are interesting for the automotive industry due to their low specific density. Fatigue strenght is important for this components. Fatigue strenght of components can be improved with mechanical surface hardening. One of the possible surface hardening processes is cavitation peening. In the master's thesis, the influence of cavitation peening parameters on solution treated (24 h at 420 °C) and solution treated aged (after that 8 h at 250 °C) samples of magnesium alloy AZ80, which has 8,5% Al and 0,5% Zn (mass fraction), was determined. The samples were hardened with different peening intensities, which increased from 1 s/mm to 20 s/mm. The following properties were evaluated: micro-hardness, residual stresses, roughness, corrosion resistance and microstructure. The values were compared with the base material and the depth of the modified surface layer was determinated. We also observed the presence of material erosion and the formation of cracks at higher intensities of cavitation peening. |
