Vpliv toplotne obdelave na lastnosti aluminijeve zlitine EN AW-2011 : diplomsko delo

Kos, Kevin (author), Fajfar, Peter (mentor), Cvahte, Peter (comentor)

Zlitina EN AW 2011 spada med toplotno utrjevalne zlitine, ki po ustrezni termomehanski obdelavi dosežejo visoke trdnostne lastnosti zaradi procesa izločevalnega utrjevanja. Glavni legirni element te zlitine je baker z masnim deležem 5-6 %. Dodatek svinca v masnem deležu med 0,2-0,6 % omogoča dobro obdelavo na avtomatskih obdelovalnih strojih. Najpogostejši izdelki so cevi, palice in profili. Namen diplomske naloge je primerjava mehanskih in mikrostrukturnih lastnosti iztiskanih palic dimenzije 35 mm, zlitine EN AW 2011, ki so bile izdelane po treh različnih tehnoloških postopkih. V prvem postopku so bile palice gašene na stiskalnici in izločevalno utrjevane, v drugem postopku so bile palice raztopno žarjene in gašene v solni kopeli, sledilo je še izločevalno utrjevanje . Tretji tehnološki postopek pa je kombinacija obojnega, to pomeni da smo palice najprej gasili na stiskalnici nato raztopno žarili in gasili v solni kopeli. Postopek smo še zaključili z izločevalnim utrjevanjem. Vhodna surovina je drog dimenzije 282 mm in dolžine 6900 mm, ki ga v stružnem centru, ki je lociran v obratu PP Cevarna, postružijo na premer 275 mm in razrežejo v okroglice dolžine 1400 mm. Iz droga smo odrezali tudi disk na katerem smo naredili na robu, sredini in pa na d/4 analizo mikrostrukture. Na disku smo izvedli tudi kemijsko analizo in pa analizo mehanskih lastnosti. Nato smo pripravljeno okroglico segreli v indukcijski peči in jo v enem primeru gasili in iztisnili, v drugem primeru smo pa neposredno po ogrevanju izvedli iztiskanje na 35 MN indirektni iztiskalnici. Uporabili smo tri žilno plosko orodje. Pri razrezu smo odvzeli vzorce vseh treh žil v stanju T1 in pa T1A. Sledilo je raztopno žarjenje in gašenje v solni kopeli na temperaturi 520 °C ± 10 °C in času 300 s nato še izločevalno utrjevanje, tako da smo prišli do stanja T6 in pa novega stanje T6A. Stanje T5A dosežemo tako, da material v stanju T1A po iztiskanju izločevalno utrjujemo. Izločevalno utrjevanje je potekalo 4 h pri temperaturi 190 °C in 12 h pri temperaturi 170 °C. Na palicah smo izvedli kemijsko analizo, analizo mehanskih in pa mikrostrukturnih lastnosti.

• Language: Slovenian
• Keywords: zlitina EN AW 2011, mehanske lastnosti, mikrostrukturne lastnosti, toplotna obdelava.
• Work type: High school thesis
• Typology: 2.11 - Undergraduate Thesis
• Organization: NTF - Faculty of Natural Sciences and Engineering
• Place of publishing: Ljubljana
• Publisher: [K. Kos]
• Year: 2021
• Number of pages: XI, 36 f.
• PID: 20.500.12556/RUL-134079
• UDC: 669
• COBISS.SI-ID: 92247043
• Publication date in RUL: 23.12.2021

Secondary language

• Language: English
• Title: Effect of heat treatment on properties of aluminium alloy EN AW-2011 : diploma work

Abstract

The EN AW 2011 alloy is one of the heat-hardening alloy that, after appropriate thermomechanical treatments, achieves high strength properties due to the processes of precipitation hardening. The main alloying element of this alloy is a copper whit a mass content of 5-6 %. The addition of lead in a mass content between 0,2-0,6 % enables good machining of automatic machine tools. The most common products are tubs, rods and profiles. The purpose of the diploma work is to compare the mechanical and microstructural properties of extruded bars dimensions 35 mm, alloy EN AW 2011, which were manufactured by three different technological procedures. In the first process, the rods were quenched on a press and precipitation hardened, in the second process the rods were solution annealed and quenched in a salt bath, followed by precipitation hardening. The third technological process is a combination of both, which means that the rods were first quenched on a press, then solution anneled and quenched in a salt bath. The process was completed whit precipitation hardening. The input raw material is a pole measuring 282 mm in length 6900 mm, which is turned to a diameter of 275 mm in the turning centre located in the PP Cevarna plant and cut to a length of 1400 mm. We also cut a disk from the pole on which we did a microstructure analysis on the edge in the middle and on the d/4. We also performed a chemical analysis on the disk and an analysis of the mechanical properties. The prepared round was then heated in an induction furnace and in one case it was quenched, and in the other case, extrusion was performed on 35 MN indirect press immediately after heating. We use three cavities flat tool. At incision, samples were taken from all three vessels in the T1 and T1A states. This was follows by solution annealing and quenching in salt bath at the temperature of 520 °C ± 10 °C for a period of 300 s follows by precipitation hardening, so that we reached the T6 state and the new T6A state. The T5A state is achieved by precipitation hardening the material in the T1A state after extrusion. Precipitation hardening was carried out for 4 hours at a temperature of 170 °C and 12 hours at the temperature of 190 °C. We also performed a chemical analysis, mechanical and microstructural properties on the rods.

• Keywords: EN AW 2011 alloy, mechanical properties, microstructural properties, heat treatment.