Lasersko površinsko pretaljevanje magnezijeve zlitine AZ80

Černe, Urban (author), Šturm, Roman (mentor)

V magistrskem delu z naslovom Lasersko površinsko pretaljevanje magnezijeve zlitine AZ80 smo vrednotili hrapavost, mikrostrukturo, mikrotrdoto, korozijsko hitrost in zaostale napetosti pred in po laserskem površinskem pretaljevanju z Nd:YAG laserjem magnezijeve zlitine AZ80 z okoli 8 mas. % Al in okoli 0,7 mas. % Zn. Pri laserskem pretaljevanju smo zaradi slabše absorptivnosti magnezija uporabili grafitni absorber. Cilj pri izbiri optimalnih procesnih parametrov je bil čim večja efektivnost procesa (čim večja velikost laserske pege in hitrost potovanja laserskega žarka), 50 % prekrivanje laserskih sledi in moč laserja, pri kateri dobimo minimalno poslabšanje hrapavosti površine. Na podlagi meritev izvedenega eksperimenta smo za optimalne laserske procesne parametre izbrali: P = 40 W, dB ≈ 1,9 mm, t = 10 ms, v = 0,5 mm/s in ν = 1 Hz. Z laserskim pretaljevanjem smo dosegli približno 3–kratno izboljšanje korozijske odpornosti pri izbranih nastavljenih pogojih. Pri pretaljevanju smo v material vnesli natezne zaostale napetosti reda 100–150 MPa, kar je približno 60 % Rp. Z laserskim pretaljevanjem smo dosegli skoraj 40 % izboljšanje mikrotrdote lasersko pretaljenega sloja v primerjavi z osnovnim vzorcem. Hrapavost pretaljenega sloja je bila Sa = 20,15 um. Z naknadnim finim brušenjem smo jo zmanjšali na Sa = 5,31 um. Globina pretaljenega sloja je bila 330 um.

• Language: Slovenian
• Keywords: magnezijeve zlitine, lasersko pretaljevanje, korozijska odpornost, zaostale napetosti, mikrotrdota, hrapavost
• Work type: Master's thesis/paper
• Typology: 2.09 - Master's Thesis
• Organization: FS - Faculty of Mechanical Engineering
• Place of publishing: Ljubljana
• Publisher: [U. Černe]
• Year: 2019
• Number of pages: XXVI, 70 str.
• PID: 20.500.12556/RUL-109713
• UDC: 621.9.048.7:669.721.5(043.2)
• COBISS.SI-ID: 16917019
• Publication date in RUL: 07.09.2019

ČERNE, Urban, 2019, Lasersko površinsko pretaljevanje magnezijeve zlitine AZ80 [online]. Master’s thesis. Ljubljana : U. Černe] . [Accessed 27 March 2025]. Retrieved from: https://repozitorij.uni-lj.si/IzpisGradiva.php?lang=eng&id=109713

Secondary language

• Language: English
• Title: Laser Surface Remelting of Magnesium Alloy AZ80

Abstract

This Master’s Thesis, entitled Laser Surface Remelting of Magnesium Alloy AZ80, presents basic information about the effect of laser surface remelting using Nd:YAG laser on: surface roughness, microstructure, microhardness, corrosion rate, and residual stresses of magnesium alloy AZ80 with approximately 8 mas. % Al and 0.7 mas. % Zn. Due to low absorption of magnesium of laser light, graphite absorber was used. One of the goals of the thesis was finding optimal laser process parameters for maximum process efficiency (i.e. biggest laser beam diameter and laser scanning speed) and 50 % laser path overlapping while using laser power with minimum negative influence on surface roughness. Based on measurements, optimal laser process parameters were selected, i.e. P = 40 W, dB ≈ 1.9 mm, t = 10 ms, v = 0.5 mm/s, and ν = 1 Hz. Surface roughness of laser remelted surface was Sa = 20.15 um. After fine grinding Sa = 5.31 um was achieved. Depth of laser remelted zone was 330 um. Microhardness of laser remelted zone was approximately 140 HV0.05, which is almost 40 % improvement compared to core. Tensile residual stresses of 100MPa to 150MPa were introduced by laser surface remelting. Corrosion rate of laser remelted surface was approximately 3 times slower compared to non–remelted surface, using Tafel extrapolation method.

• Keywords: magnesium alloys, laser remelting, corrosion resistance, residual stresses, microhardness, surface roughness