Lasersko varjenje sive litine

Purkeljc, Kristjan (author), Klobčar, Damjan (mentor), Trdan, Uroš (comentor)

Liti izdelki so zaradi relativno ugodnih mehanskih lastnosti in nižje cene izdelave v visokoserijski proizvodnji zelo razširjeni v različnih industrijah in konstrukcijah. V različnih fazah izdelka jih je treba tudi variti ali popravljati z reparaturnim varjenjem. Lasersko varjenje sive litine predstavlja velik izziv zaradi njihove slabe varivosti. Kemična sestava sive litine povzroča namreč večje težave z varivostjo, ki se odražajo v pojavu razpok in penjenju taline. Uspešno lasersko varjenje je mogoče z ustrezno temperaturo predgrevanja varjencev, izbranimi tehnološkimi parametri in z ustrezno izbiro dodajnega materiala. V diplomskem delu smo raziskovali in predstavili značilne osnovne lastnosti materialov ter vpliv dodajnih materialov pri varjenju različnih vrst sivih litin. Predstavili smo varjenje obravnavanih zlitin, s poudarkom na laserskem varjenju. Izvedli smo lasersko varjenje nodularne in lamelarne sive litine ob uporabi različnih dodajnih materialov. Zvarne spoje smo ovrednotili z vizualno kontrolo, metalografsko analizo in meritvijo trdote. Na podlagi izvedenih meritev smo ovrednotili grafe trdote zvarov v odvisnosti od globine zvara. Na podlagi vizualne analize, mikroskopije ter meritve trdote bi za varjenje nodularne litine izbrali dodajni material NiTi4. Na vzorcu smo opazili manjšo lokalno poroznost drugače pa je bil var brez večjih nepravilnosti. Povprečna trdota vara je bila 389,7 ± 86,3 HV0,3. Za varjenje lamelarne litine bi izbrali med dodajnima materialoma AMPCO ter NiTi4 katera sta oba pokazala dobre rezultate. Povprečna trdota vara za AMPCO je znašala 391,5 ± 165,7 HV0,3 za NiTi4 pa 356.5 ± 59.5 HV0,3.

• Language: Slovenian
• Keywords: laser, lasersko varjenje, nodularna siva litina, lamelarna siva litina, trdota, mikrostruktura
• Work type: Bachelor thesis/paper
• Typology: 2.11 - Undergraduate Thesis
• Organization: FS - Faculty of Mechanical Engineering
• Place of publishing: Ljubljana
• Publisher: [K. Purkeljc]
• Year: 2024
• Number of pages: XX, 55 str.
• PID: 20.500.12556/RUL-154856
• UDC: 621.791.725:669.131.6:620.17(043.2)
• COBISS.SI-ID: 188430083
• Publication date in RUL: 06.03.2024

PURKELJC, Kristjan, 2024, Lasersko varjenje sive litine [online]. Bachelor’s thesis. Ljubljana : K. Purkeljc. [Accessed 25 April 2025]. Retrieved from: https://repozitorij.uni-lj.si/IzpisGradiva.php?lang=eng&id=154856

Secondary language

• Language: English
• Title: Laser welding of gray cast iron

Abstract

Due to favourable mechanical properties and lower production costs in high-volume production, cast products are very widespread across different industries and constructions. Different product phases require welding and reparation using repair welding. Laser welding of grey cast iron is very challenging due to its poor weldability. In fact, the chemical composition of grey cast iron causes large problems related to weldability, reflected in the incidence of cracks and alloy foam. Successful laser welding can be ensured by selecting the appropriate workpiece preheating temperature, technological parameters and appropriate filler material. In the paper, we studied and presented basic characteristic properties of materials and the effect of filler materials on welding of different types of grey cast iron. Welding of the studied alloys was presented, with an emphasis on laser welding. We conducted laser welding of ductile and lamellar grey cast iron using different filler materials. Welding joints were assessed carrying out a visual inspection, a metallographic analysis and hardness measurements. Based on the measurements conducted, we assessed the graphs showing joint hardness depending on the joint depth. Stemming from a visual analysis, microscopy and hardness measurements, we would select the NiTi4 filler material for the welding of the nodular cast iron. Except for then small local porosity on the sample, the weld contained no major irregularities. Average weld hardness was 389.7 ± 86.3 HV0,3. For the welding of lamellar cast iron, we would choose between the AMPCO and NiTi4 filler materials, as both yielded good results. Average weld harness of AMPCO was 391.5 ± 165.7 HV0,3, while the average weld hardness of NiTi4 was 356.5 ± 59.5 HV0,3.

• Keywords: laser, laser welding, ductile grey cast iron, lamellar grey cast iron, hardness, microstructure