Vpliv procesnih parametrov na mikrostrukturo induktivno kaljenega valja OTV1C jekla

Založnik, Žan (author), Markoli, Boštjan (mentor)

V okviru diplomskega dela smo analizirali mikrostrukturo induktivno kaljenega valja, izdelanega iz orodnega jekla OTV1C. To jeklo se pogosto uporablja za izdelavo valjev za delo v hladnem, pri čemer je nujna odpornost površine na obrabo. Ta temelji na ustrezno velikih in enakomerno porazdeljenih karbidih različnih tipov. Testni valj je bil induktivno kaljen z različnimi parametri – spreminjali smo temperaturo kaljenja in hitrost pomika valja skozi induktor. Iz testnega valja smo nato izrezali diske, iz katerih smo potem izdelali preizkušance. Vzorce smo zbrusili in spolirali ter na koncu še jedkali. Tako pripravljene vzorce smo si ogledali pod svetlobnim mikroskop om, vrstičnim elektronskim mikroskopom SEM in opredelili velikost kristalnih zrn po standardu ASTM E112. Pri preiskavi in analizi rezultatov smo se osredotočili predvsem na velikost in razporejenost karbidov v vzorcih preiskovanega jekla . Pri tem smo uporabili sodobne preiskovalne metode, kot so svetlobna in elektronska mikroskopija, rentgenska fazna analiza in študij pomembnih faznih diagramov. Ugotovili smo, da imamo pri nižji temperaturi kaljenja v matrici večje število manjših karbidov, pri višji temperaturi pa imamo manjše število karbidov, ki so večji. To je posledica raztapljanja manjših karbidov in rasti večjih karbidov (Ostwaldovo zorenje). Hitrost pomika valja skozi induktor vpliva na obliko karbidov. Pri nižji hitrosti pomika pride do prenasičenja osnove ali matrice, kar posledično vpliva na obliko karbidov – karbidi so bolj okrogli. Pri višji hitrosti pomika pa karbidi nimajo toliko časa za sferoidizacijo in so zato bolj poligonalni.

• Language: Slovenian
• Keywords: mikrostruktura, karbidi, toplotna obdelava, temperatura kaljenja, hitrost pomika valja skozi induktor
• Work type: Bachelor thesis/paper
• Organization: NTF - Faculty of Natural Sciences and Engineering
• Year: 2020
• PID: 20.500.12556/RUL-120897
• COBISS.SI-ID: 32958211
• Publication date in RUL: 26.09.2020

ZALOŽNIK, Žan, 2020, Vpliv procesnih parametrov na mikrostrukturo induktivno kaljenega valja OTV1C jekla [online]. Bachelor’s thesis. [Accessed 16 March 2025]. Retrieved from: https://repozitorij.uni-lj.si/IzpisGradiva.php?lang=eng&id=120897

Secondary language

• Language: English
• Title: Influence of processing parameters on microstructure of steel

Abstract

As part of the diploma work, we analysed the microstructure of an induction hardened roll, made out of OTV1C tool steel. This type of steel is often used for the manufacturing of rolls for cold rolling with the necessary wear resistance of the surfaces. Its basis lies in appropriately large and evenly distributed carbides of different types. The test roll was induction hardened with different parameters – we changed the austenitization temperature and the speed of hardening. Discs were then cut from the test roll and samples were made from this. The samples were ground, polished and finally etched. Samples prepared in this way were examined under a light microscope, a Scanning Electron Microscope SEM and the grain size was determined according to the ASTM E112 standard. In the investigation and the analysis of the results, we focused on the size and distribution of carbides in the samples of investigated steel. We used modern investigative methods, such as light and electron microscopy, X-ray phase analysis and study of important phase diagrams. We found out that at lower austenitization temperatures there is a large number of smaller carbides in the matrix and at higher temperatures we have a smaller number of carbides, which are larger. This results from the dissolution of smaller carbides and the growth of larger carbides (Ostwald ripening). The hardening speed of the roll affects the shape of the carbides. At a lower speed there is an oversaturation of the base or matrix, which affects the shape of the carbides – the carbides are thus more round. At a higher speed, however, carbides do not have as much time for the spheroidization and are thus more polygonal.

• Keywords: microstructure, carbides, heat treatment, austenitization temperature, hardening speed