Vpliv žarjenja na preoblikovalne lastnosti folije iz aluminijeve zlitine EN AW 8079 : magistrsko delo

Godec, Domen (author), Fajfar, Peter (mentor), Volšak, Darja (co-mentor)

Namen magistrskega dela je bil spremljati lastnosti materiala skozi proizvodnji proces in ugotoviti pogoje medprocesnega žarjenja, pri katerih bomo dobili industrijsko izdelano folijo, zlitine EN AW 8079 in debeline 0,1 mm, z najboljšimi preoblikovalnimi in globokovlečnimi lastnostmi. Vhodno surovino je predstavljalo 9 toplo valjanih trakov; vsak izmed teh je imel določeno lastno tehnološko pot. Variirala sta se parametra temperature in debeline medprocesnega žarjenja, ki je potekalo pri kombinacijah temperatur 350 °C, 400 °C in 450 °C in debelin 0,6 mm, 0,8 mm in 1,2 mm. Materialu, ki je bil vzorčen skozi proces, so bile z eksperimentalnimi metodami določene vrednosti dogovorne meje tečenja Rp0,2, natezne trdnosti Rm, raztezka do porušitve A50 oz. A100, ušesenja z in vrednosti indeksa Erichsenovega preizkusa IE. Opaziti je, da se material z naraščajočo stopnjo hladne deformacije utrjuje, hkrati pa se mu povečuje anizotropija. Ob presegu določene stopnje deformacije pri hladnem valjanju začne aktivno potekati proces dinamične poprave. Vrednosti dogovorne meje tečenja Rp0,2 po medprocesnem žarjenju prikazujejo najnižje vrednosti pri debelini medprocesnega žarjenja 1,2 mm in najvišje vrednosti pri debelini medprocesnega žarjenja 0,6 mm, medtem ko so najmanjša rekristalizirana zrna po medprocesnem žarjenju dosežena pri debelini medprocesnega žarjenja 0,8 mm, največja rekristalizirana zrna pa pri debelini medprocesnega žarjenja 1,2 mm. Vrednost dogovorne meje tečenja Rp0,2 mehko žarjene folije debeline 0,1 mm po končnem žarjenju narašča z debelino medprocesnega žarjenja in s temperaturo medprocesnega žarjenja. Najboljša kombinacija globokovlečnih lastnosti in preoblikovalnosti je dosežena pri debelini medprocesnega žarjenja 1,2 mm in temperaturi medprocesnega žarjenja 350 °C; zelo primerljiva kombinacija omenjenih vrednosti je prav tako dosežena pri debelini medprocesnega žarjenja 0,6 mm in temperaturi medprocesnega žarjenja 450 °C.

• Language: Slovenian
• Keywords: Aluminijeva zlitina EN AW 8079, preoblikovanje, parametri žarjenja, mehanske lastnosti, velikost kristalnih zrn, sposobnost globokega vleka.
• Work type: Master's thesis/paper
• Typology: 2.09 - Master's Thesis
• Organization: NTF - Faculty of Natural Sciences and Engineering
• Place of publishing: Ljubljana
• Publisher: [D. Godec]
• Year: 2021
• Number of pages: XXII, 112 f.
• PID: 20.500.12556/RUL-128243
• UDC: 669
• COBISS.SI-ID: 71661059
• Publication date in RUL: 07.07.2021

Secondary language

• Language: English
• Title: Effects of annealing on formability properties of aluminium foil EN AW 8079 : master's thesis

Abstract

The purpose of the master's thesis was to analyse material properties of the material through the different stages of the production process and to determine the best combination of inter-process annealing parameters (inter-process annealing temperature and thickness), at which the best deep drawing properties of the final product, industrial produced, 0,1 mm thick, soft annealed foil from alloy EN AW 8079, is achieved. The entry material was represented by 9 hot rolled strips; each of them had been designated a unique process path. The variable parameters had been the inter-process annealing temperature and thickness, which were 300 °C, 400 °C, 450 °C and 0,6 mm, 0,8 mm 1,2 mm, respectively. Yield strength Rp0,2, tensile strength Rm, elongation to fracture A50 or A100, earring z and index of Erichsen cupping test IE values were experimentally determined for the sampled material. It is observed that material hardens with an increasing degree of cold deformation and at the same time, its anisotropy increases. When a certain degree of deformation is exceeded during cold rolling, the process of dynamic repair begins to take place actively. The values of the yield strength Rp0,2 after inter-process annealing show the lowest values at the inter-process annealing thickness of 1,2 mm and the highest values at the inter-process annealing thickness of 0,6 mm, while the smallest recrystallized grains after inter-process annealing are reached at the inter-process annealing thickness of 0,8 mm, and the largest recrystallized grains at an inter-annealing thickness of 1,2 mm. The value of the yield strength Rp0,2 of the soft annealed, 0,1 mm thick foil, after the final annealing, increases with the thickness of the inter-process annealing and with the temperature of the inter-process annealing. The best combination of deep drawing properties and deformability is achieved at an inter-process annealing thickness of 1,2 mm and an inter-annealing temperature of 350 °C; a very comparable combination of deep drawing properties and deformability is achieved at an inter-process annealing thickness of 0,6 mm and an inter-annealing temperature of 450 °C.

• Keywords: Aluminium alloy EN AW 8079, forming, annealing parameters, mechanical properties, grain size, deep drawing capabilities.