Vpliv deformacije in toplotne obdelave na mehanske lastnosti aluminijeve zlitine EN AW-5754

Mlinar, Timotej (author), Fajfar, Peter (mentor), Cvahte, Peter (co-mentor)

Aluminij-magnezijeve zlitine so zaradi svoje dobre korozijske obstojnosti in dokaj visokih trdnostnih lastnosti dobro zastopane v transportni industriji. Le-ta teži k izdelavi varčnejših in okolju prijaznejših prevoznih sredstev z dovolj visokimi mehanskimi lastnostmi. V diplomskem delu smo obravnavali vpliv deformacije in toplotne obdelave na mehanske lastnosti aluminijeve zlitine EN AW 5754. Vhodna surovina je bila toplo valjana pločevina (vzorec 1) debeline 5 mm, katera je z 212 MPa kazala najnižjo vrednost natezne trdnosti. Nadalje je bila pločevina še hladno valjana v treh prehodih in vsak prehod je bil posebej obravnavan. Pločevina zadnjega prehoda (vzorec 4) debeline 2 mm je kazala najvišjo natezno trdnost z vrednostjo 319 MPa, vendar je njen raztezek ob porušitvi znašal zgolj 5,7 %, napram vzorcu 1, kjer je raztezek ob porušitvi dosegel vrednost 27,5 %. Eksponent deformacijskega utrjevanja se pri kovinah po navadi giblje od 0,1 do 0,5 in kaže sposobnost preoblikovanja materiala. Vzorec 1 ima najboljšo preoblikovalnost z vrednostjo eksponenta deformacijskega utrjevanja 0,2984. Le-ta med hladnim valjanjem postopoma pada in pri vzorcu 4 doseže vrednost 0,0764. Toplotna obdelava vzorcev je potekala v temperaturnem območju od 240 °C do 300 °C pri časih 60 min, 240 min in 480 min. Med toplotno obdelavo so se vrednosti mehanskih lastnosti hladno valjanih vzorcev približevale vrednostim toplo valjane pločevine.

• Language: Slovenian
• Keywords: aluminijeva zlitina, deformacija, toplotna obdelava, natezni preizkus, mehanske lastnosti
• Work type: Bachelor thesis/paper
• Organization: NTF - Faculty of Natural Sciences and Engineering
• Year: 2020
• PID: 20.500.12556/RUL-120956
• COBISS.SI-ID: 31469059
• Publication date in RUL: 28.09.2020

Secondary language

• Language: English
• Title: Effect of deformation and heat treatment on the mechanical properties of aluminium alloy EN AW-5754

Abstract

Aluminum-magnesium alloys are well represented in the transport industry due to their good corrosion resistance and relatively high strength properties. The transport industry strives to produce more economical and environmentally friendly means of transport with sufficiently high mechanical properties. In the diploma work we investigated the influence of deformation and heat treatment on the mechanical properties of aluminum alloy EN AW 5754. The input raw material was hot rolled sheet metal (sample 1) 5 mm thick, which showed the lowest value of tensile strength with 212 MPa. Furthermore, the sheet was cold rolled in three passes and each pass was treated separately. Cold rolled sheet metal (sample 4) 2 mm thick showed the highest tensile strength with a value of 319 MPa, but its elongation at break was only 5.7 %, compared to sample 1, where the elongation at break reached 27.5 %. The strain hardening exponent for metals usually ranges from 0.1 to 0.5 and shows the ability to transform the material. Sample 1 has the best deformability with a value of the strain hardening exponent of 0.2984, which gradually decreases during cold rolling and reaches a value of 0.0764 in sample 4. The heat treatment of the samples took place in the temperature range from 240 °C to 300 °C at times of 60 min, 240 min and 480 min. During the heat treatment, the values of the mechanical properties of the cold-rolled samples approached the values of the hot-rolled sheet.

• Keywords: aluminium alloy, deformation, heat treatment, tensile test, mechanical properties