Mikrostruktura in mehanske lastnosti zlitine Ti6Al4V izdelane po postopku selektivnega laserskega taljenja

Pogačar, Maja (author), Bizjak, Milan (mentor), Paulin, Irena (comentor)

Titan in njegove zlitine se pogosto uporabljajo v različnih industrijah (avtomobilski, letalski, farmacevtski …), saj imajo relativno nizko gostoto, visoko trdnost in dobro korozijsko odpornost. Izdelava titanovih polizdelkov in izdelkov po tradicionalnih tehnologijah je zelo draga, zato so za njihovo izdelavo začeli uporabljati dodajalne tehnologije. Dodajalne (aditivne) tehnologije (angl. Additive Manufacturing – AM) so procesi izdelave, ki temeljijo na dodajanju materiala v slojih in predstavljajo nov način izdelave strojnih oziroma konstrukcijskih elementov. Omogočajo nam izdelavo izdelkov z zapletenimi geometrijami, ki jih ni mogoče izdelati s tradicionalnimi obdelovalnimi postopki. Ena izmed najbolj uporabljenih dodajalnih tehnologij pri kovinskih materialih je selektivno lasersko taljenje (SLM). To je postopek AM, ki omogoča gradnjo izdelka neposredno iz praškovne postelje z uporabo visokoenergijskega laserskega žarka. Namen in cilj magistrskega dela je bil ugotoviti, kako različni procesni parametri vplivajo na mehanske lastnosti, mikrostrukturo in korozijsko odpornost SLM vzorcev iz prahu zlitine Ti6Al4V. V ta namen smo izdelali procesne mape, in sicer mape poroznosti in mape trdot. Iz izdelanih procesnih map smo določili, pri katerih parametrih dobimo največjo trdoto in najmanjši delež poroznosti. Rezultati analize procesnih map so služili za izbiro optimalnih procesnih parametrov, ki smo jih uporabili pri nadaljnji izdelavi SLM-vzorcev. Pri izbranih procesnih parametrih smo izdelali tri različne oblike in dimenzije vzorcev. Za potenciodinamske meritve so bili vzorci v obliki nizkih valjev. Ploščate vzorce za izdelavo nateznih preizkušancev smo tiskali v dveh različnih smereh, in sicer v smeri gradnje vzorca po širini, tj. od strani do strani, pravokotno na dolžino in debelino ter po debelini. Z uporabo svetlobne in vrstične elektronske mikroskopije smo naredili metalografske preiskave SLM vseh vzorcev kockaste oblike, kjer smo določili mikrostrukturo in delež nastalih faz v materialu, narejenem po SLM-postopku.

• Language: Slovenian
• Keywords: dodajalna tehnologija, selektivno lasersko taljenje, mehanske lastnosti, mikrostruktura, Ti6Al4V, korozija
• Work type: Master's thesis/paper
• Organization: NTF - Faculty of Natural Sciences and Engineering
• Year: 2022
• PID: 20.500.12556/RUL-138612
• COBISS.SI-ID: 127293699
• Publication date in RUL: 03.08.2022

POGAČAR, Maja, 2022, Mikrostruktura in mehanske lastnosti zlitine Ti6Al4V izdelane po postopku selektivnega laserskega taljenja [online]. Master’s thesis. [Accessed 18 March 2025]. Retrieved from: https://repozitorij.uni-lj.si/IzpisGradiva.php?lang=eng&id=138612

Secondary language

• Language: English
• Title: Microstructure and mechanical properties of Ti6Al4V alloy fabricated by selective laser melting

Abstract

Titanium and its alloys, particularly Ti6Al4V, are widely used, especially in the aerospace and medicine due to their relatively low density, high strength and good corrosion resistance. However, there are formidable challenges in casting, forming and machining titanium alloys, which result in final products, that are considerably more expensive. Nowadays, Additive Manufacturing (AM) is considered as one of the most promising technologies for metallic materials due to its ability to produce complex geometries with high density and accuracy in a short amount of time. AM is a process based on layer-by-layers method and represents a new way of making machine or structural elements. It allows us to make products with complex geometries from CAD base data, that cannot be made with traditional metallurgical processes. One of the most used technologies for metals alloys is selective laser melting (SLM). This is a powder-based AM process, which consists of melting and solidifying metallic powder layers by using high energy laser beam. This master's thesis determines which conditions are the most favourable to be used during SLM process for Ti6Al4V alloy powder by using process maps and the effect of different process parameters on the mechanical properties, microstructure and corrosion resistance of SLM samples from Ti6Al4V alloy powder. By using three different laser powers and four different scanning speeds, the process maps of hardness and porosity were created. With these results, we determined the optimal parameters with the highest hardness and the lowest fraction of porosity for the SLM Ti6Al4V samples, suitable for further production. The samples for mechanical properties were made in two different directions at selected printing process parameters - different laser power and scanning speed. Three different shapes and dimensions of the samples were made. For corrosion tests (potentiodynamic measurements) samples were made in the form of low cylinders. For mechanical testing (tensile tests), flat samples were made. We also made samples in the form of cubes for metallographic analysis (light and scanning electron microscopy), where the microstructure and chemical composition in the material made by the SLM process is determined.

• Keywords: additive manufacturing, selective laser melting, Ti6Al4V alloy, mechanical properties, microstructure, corrosion