Primerjava razvoja nekovinskih vključkov v jeklu 16MnCr5S pri različnih postopkih izdelave

Vengust, Vid (author), Knap, Matjaž (mentor), Drofelnik, Nejc (comentor)

V sklopu tega diplomskega dela je predstavljen razvoj nekovinskih vključkov v jeklu 16MnCrS5, izdelanem po dveh različnih tehnologijah. Jeklo 16MnCrS5 je jeklo s povišano obdelovalnostjo, ki se uporablja predvsem v avtomobilski industriji za izdelavo mehansko obremenjenih delov kompleksnih oblik. Različne tehnologije izdelave jekla imajo vpliv na kemično sestavo jekla in povprečno sestavo nekovinskih vključkov v jeklu, kar se odraža v končnih lastnostih materiala, ki jih zahteva uporabnik. Nekovinski vključki nastanejo na začetku procesa obdelave jekla, ko z dodajanjem različnih elementov, ki imajo veliko afiniteto do kisika, znižamo količino kisika, raztopljenega v talini. Sestava nekovinskih vključkov je odvisna od kemične sestave taline, žlindre in snovi, ki jih dodajamo v jeklo in se spreminja glede na to, kako poteka proces. Namen te naloge je bil opredeliti vpliv razlike v procesih na razvoj vključkov. Eksperimentalno delo je zajemalo vzorčenje dveh industrijskih šarž jekla, izdelanih v jeklarni podjetja Štore Steel, ter analizo odvzetih vzorcev z različnimi sodobnimi metodami s poudarkom na avtomatski analizi vključkov.. Iz rezultatov smo ugotovili, da glavno razliko v razvoju vključkov v jeklu predstavlja sredstvo za modifikacijo aluminatnih vključkov, ki nastanejo v procesu dezoksidacije. V primeru tehnologije, prilagojene nadaljnji predelavi s hladnim kovanjem, vključke modificiramo s CaC2, v primeru klasične tehnologije pa s CaSi. Obe sredstvi povzročita nastanek silikatnih vključkov, ki poslabšajo lastnosti jekla, vendar je pojav bistveno bolj izrazit pri modifikaciji vključkov s CaSi.

• Language: Slovenian
• Keywords: jeklo 16MnCrS5, čistost, nekovinski vključki, modifikacija vključkov, avtomatska analiza vključkov
• Work type: Bachelor thesis/paper
• Organization: NTF - Faculty of Natural Sciences and Engineering
• Year: 2019
• PID: 20.500.12556/RUL-110290
• COBISS.SI-ID: 1834079
• Publication date in RUL: 13.09.2019

Secondary language

• Language: English
• Title: A comparison of the development of non-metallic inclusions in 16MnCr5S steel in relation to different process routes

Abstract

This diploma presents the development of non-metallic inclusions in 16MnCrS5 steel that has been manufactured through two different process routes. 16MnCrS5 is a high-machinability steel that is used in the automobile industry for the manufacturing of complex-shaped parts that need to withstand high mechanical loads. Different process routes effect the chemical composition and inclusion structure of steel, which influences the final properties of the material. Non metallic inclusions are formed at the start of the ladle furnace process by the addition of different elements with high affinity towards oxygen to the steel melt with the purpose of lowering the content of soluble oxygen in steel. The composition of non-metallic inclusions depends on the chemcical composition of the steel melt, the slag and additions. The aim of this diploma is to assess the influence of the differences in proces routes on the development of non-metallic inclusions. The experimental part consisted of the sampling of two industrial heats of steel, made in the Štore Steel steel plant and the analysis of the samples with modern analysis methods, focusing on the automatic analysis of inclusions. The results show that the main difference in the development of inclusions in steel presents itself in the means of modifications of alumina inclusions that are formed in the deoxidation phase. In the process route, designed for further processing with cold forging, the inclusions are modified with CaC2 and in the case of the classic process route they are modified with CaSi. Both types of modification cause the formation of silica inclusions which are detrimental to the final properties of steel, however the effect is more pronounced in the case of modification with CaSi.

• Keywords: 16MnCrS5 steel, cleanliness, non-metallic inclusions, inclusion modification, automated inclusion analysis