Optimizacija dodatka kalcija za modifikacijo nekovinskih vključkov pri vzmetnem jeklu 51CrV4

Smole, Lucija (avtor), Knap, Matjaž (mentor), Vengust, Vid (komentor)

V diplomski nalogi smo preučevali vpliv različnih dodatkov kalcija na livnost in čistost vzmetnega jekla 51CrV4. Cilj je bil optimizirati količino dodanega kalcija v obliki CaSi žice za učinkovito modifikacijo nekovinskih vključkov in v proizvodnem procesu preveriti možnost zamenjave CaSi žice s Ca-solid žico. Eksperimentalni del smo izvedli v podjetju Štore Steel. Analizirali smo šarže jekla 51CrV4 z dodatkom CaSi žice dolžine 75 m in 45 m ter Ca-solid žice dolžine 30 m. Livnost jekla smo ovrednotili s pomočjo internega sistema za ocenjevanje livnosti, čistost jekla pa z določevanjem nekovinskih vključkov po metodi K in po metodi A. Izkoristek kalcijeve žice smo določili na podlagi spremembe vsebnosti kalcija v jeklu pred in po dodatku žice. Za podrobnejšo analizo kemične sestave vključkov smo izvedli avtomatsko analizo vključkov. Rezultati so pokazali, da različni dodatki kalcija niso vplivali na livnost jekla, saj so vse analizirane šarže dosegle optimalno oceno livnosti. Največji izkoristek kalcija je bil dosežen pri uporabi Ca-solid žice. Pri vrednotenju vključkov po metodi K sta manjša dolžina CaSi žice in uporaba Ca-solid žice pokazali boljše rezultate v primerjavi s standardnim dodatkom CaSi žice, tj. 75 m. Avtomatska analiza je potrdila učinkovitejšo modifikacijo aluminatnih vključkov pri uporabi Ca-solid žice. Zaradi doseganja ustrezne livnosti in čistosti smo zaključili, da sta zmanjšanje dodatka CaSi in uporaba Ca-solid primerna za vpeljavo v redni proizvodni proces.

• Jezik: Slovenski jezik
• Ključne besede: jeklo 51CrV4, nekovinski vključki, modifikacija, CaSi žica, Ca-solid žica
• Vrsta gradiva: Diplomsko delo/naloga
• Organizacija: NTF - Naravoslovnotehniška fakulteta
• Leto izida: 2026
• PID: 20.500.12556/RUL-188088
• Datum objave v RUL: 18.09.2026

Sekundarni jezik

• Jezik: Angleški jezik
• Naslov: Optimization of Calcium addition for modification of non-metallic inclusions in 51CrV4 spring steel

Izvleček

In this thesis, the influence of different calcium additions on the castability and cleanliness of 51CrV4 spring steel was investigated. The aim was to optimize the amount of calcium added in the form of CaSi wire to achieve effective modification of non-metallic inclusions and to evaluate the possibility of replacing CaSi wire with Ca-solid wire in the production process. The experimental part was performed at Štore Steel, where 51CrV4 steel with additions of 75 m and 45 m CaSi wires and a 30 m Ca-solid wire were analysed. The castability of the steel was evaluated using internally developed castability assessment system, while steel cleanliness was determined by evaluating non-metallic inclusions according to the K method and the A method. The calcium wire yield was determined based on the change in calcium content in the steel before and after calcium wire addition. For a more detailed analysis of the chemical composition of inclusions, automatic inclusion analysis was performed. The results showed that different calcium additions had no influence on steel castability, as all analysed heats achieved an optimal castability rating. The highest calcium yield was achieved using Ca-solid wire. Evaluation of non-metallic inclusions using the K method showed that the reduced amount of CaSi wire and the use of Ca-solid wire resulted in better results compared to the standard addition of 75 m CaSi wire. Automatic inclusion analysis confirmed more effective modification of alumina inclusions when using Ca-solid wire. Based on the required castability and steel cleanliness, it was concluded that reducing CaSi addition and the use of Ca-solid wire are suitable for regular production process.

• Ključne besede: 51CrV4 steel, non-metallic inclusions, modification, CaSi wire, Ca-solid wire