Vpliv časa vakuumiranja na razvodičenje jekla in nekovinske vključke pri jeklu OCR12VM

Mlinar, Klemen (author), Knap, Matjaž (mentor)

V diplomskem delu je predstavljena problematika vsebnosti vodika in nekovinskih vključkov v orodnem jeklu. Opisani so zakoni topnosti in glavni vplivni parametri pri vsebnosti vodika v jeklu. Predstavljen je postopek vakuumskega razplinjevanja jeklene taline, ki ga jeklarji uporabljajo z namenom odprave vodika. V okviru diplomskega dela so opisani tudi ugodni pogoji za nastanek nekovinskih vključkov in posledice za jeklo. V delu je zajeta tudi tematika modifikacije nekovinskih vključkov s streljanjem oplaščene žice v talino. Raziskovali smo tudi vpliv časa vakuumiranja na stopnjo razžveplanja taline. V sklopu 28 šarž jekla kvalitete OCR12VM smo med proizvodnjo v jeklarni izvajali meritve vsebnosti vodika, pri čemer smo poskušali določiti čas vakuumiranja, ki še zagotavlja zadostno odpravo vodika in nekovinskih vključkov. Nekovinske ključke smo kategorizirali po metodi K na podlagi standarda DIN 50602 ter po metodi A na podlagi standarda ASTM E45.

• Language: Slovenian
• Keywords: Orodno jeklo, vodik, nekovinski vključki, žlindra, VPP, modifikacija, razplinjevanje.
• Work type: Bachelor thesis/paper
• Organization: NTF - Faculty of Natural Sciences and Engineering
• Year: 2017
• PID: 20.500.12556/RUL-96279
• Publication date in RUL: 28.09.2017

Secondary language

• Language: English
• Title: The influence of vacuuming time on hydrogen outgassing and non-metallic inclusions in steel OCR12VM

Abstract

The thesis presents the problem of hydrogen and non-metallic inclusion content in tool steel. The laws of solubility and the main influence parameters on the hydrogen content of steel are described. The procedure of vacuum degassing of the steel melt, which steelmakers use for the purpose of removing hydrogen, is presented. The diploma paper also describes favorable conditions for the formation of non-metallic inclusions and implications they have on the steel. The paper also deals with the modification of non-metallic inclusions by the method of shooting a coated wire into the melt. Lastly, we studied the influence of vacuuming time on the degree of desulphurisation of the melt. During the production in the steelworks of Metal Ravne we performed measurements of hydrogen content within 28 batches of steel grade OCR12VM, whereby we attempted to determine the vacuum time which still ensures sufficient elimination of hydrogen and non-metallic inclusions. Non-metallic inclusions were classified according to the K method, based on the DIN 50602 standard and method A, based on the ASTM E45.

• Keywords: Tool steel, hydrogen, non-metallic inclusions, slag, VAD, modification, degassing.