Vpliv procesnih parametrov na mehanske lastnosti zlitine EN AW 7020 v stanju T5 : diplomsko delo

Juhart, Tadej (author), Fajfar, Peter (mentor), Cvahte, Peter (comentor)

Aluminijeve zlitine serije 7xxx spadajo med tiste aluminijeve zlitine, ki dosegajo najvišje mehanske lastnosti, le-te dosegajo po staranju, saj imajo sposobnost izločevalnega utrjevanja. V okviru diplomske naloge smo raziskovali vpliv dveh programov homogenizacijskega žarjenja na preoblikovalne lastnosti zlitine EN AW 7020, med vročim iztiskovanjem in vpliv homogenizacije na kasnejšo toplotno obdelavo – umetno staranje. Po umetnem staranju smo na materialu izvajali natezni preizkus, izmerili trdoto po Brinelu in izvedli metalografsko analizo. Opazili smo, da je homogenejši material že v samem začetku po iztiskavanju, torej v stanju T1 imel rekristalizirano obrobno cono, ta je negativno vplivala na mehanske lastnosti profilov. Dodatna slabost je bila, da se je obrobna cona med umetnim staranjem na 135 °C širila linearno s časom staranja. Pozitivna stran homogenejše zlitine, pa se je izkazala s tem, da so bili izločki po umetnem staranju manjši in posledično bolje porazdeljeni po ?Al matrici, zaradi česar smo pri daljših časih umetnega staranja homogenejše zlitine presegli mehanske lastnosti isti čas umetno starane standardno homogenizirane zlitine. Iz razloga širjenja obrobne cone pa so kasneje mehanske lastnosti homogenejše zlitine hitro upadle.

• Language: Slovenian
• Keywords: aluminij, homogenizacijsko žarjenje, iztiskavanje v vročem, toplotna obdelava, mehanske lastnosti
• Work type: Bachelor thesis/paper
• Typology: 2.11 - Undergraduate Thesis
• Organization: NTF - Faculty of Natural Sciences and Engineering
• Place of publishing: Ljubljana
• Publisher: [T. Juhart]
• Year: 2021
• Number of pages: XIII, 40 str.
• PID: 20.500.12556/RUL-130230
• UDC: 669
• COBISS.SI-ID: 83656707
• Publication date in RUL: 11.09.2021

JUHART, Tadej, 2021, Vpliv procesnih parametrov na mehanske lastnosti zlitine EN AW 7020 v stanju T5 : diplomsko delo [online]. Bachelor’s thesis. Ljubljana : T. Juhart. [Accessed 16 March 2025]. Retrieved from: https://repozitorij.uni-lj.si/IzpisGradiva.php?lang=eng&id=130230

Secondary language

• Language: English
• Title: Influence of the process parameters on the mechanical properties of EN AW 7020 alloy in T5 state : diploma work

Abstract

Aluminium alloys of the 7xxx series are among those aluminum alloys that achieve the highest mechanical properties, they are achieved after aging, as they have the ability of precipitation hardening. As part of the diploma thesis, we investigated the influence of two programs of homogenization heat treatment on the formability of EN AW 7020 aluminium alloy during hot extrusion and the influence of homogenization on the subsequent heat treatment - artificial aging. After artificial aging, a tensile test was performed on the material, Brinel hardness was measured, and metallographic analysis was performed. We observed that the more homogeneous material already had recrystallized peripheral zone in the beginning after extrusion, ie. in the T1 state. Recrystallized zone negatively affected the mechanical properties of the profiles. An additional disadvantage was that the peripheral cone expanded during artificial aging at 135 °C, linearly with the aging time. The positive side of the more homogeneous alloy was that the precipitates after artificial aging were smaller and consequently better distributed along the αAl matrix, which resulted in higher mechanical properties. Tested homogenenized alloy exceeded the mechanical properties of the same time artificially aged standardly homogenized alloy. However, due to the expansion of the peripheral zone, the mechanical properties of the more homogeneous alloy later declined rapidly.

• Keywords: aluminium, homogenization annealing, extrusion, heat treatment, mechanical properties