Effect of additions of FeTi70R alloy on inclusion characteristics in Fe-40Ni-20Cr steels
2015 (English)In: Proceedings of the 6th International Congress on the Science and Technology of Steelmaking, ICS 2015, Chinese Society for Metals , 2015, 797-800 p.Conference paper (Refereed)
It is well known that ferroalloys, which are used for alloying of different steels, contain different harmful non-metallic inclusions and impurities. As this can significantly affect the cleanliness of the steel (especially in production of high quality alloy steels), it is important to know what happens when ferroalloys are added to the melt. In this work, characteristics of non-metallic inclusions (such as composition, size and number) were investigated in the commercially produced FeTi70R ferroalloy (∼70% Ti), which is used in the steelmaking industry for deoxidation and alloying of different steel grades. It was found that this FeTi alloy contains some amount of complex oxides, which sizes can reach 50 - 150μm. A composition analysis of these complex inclusions showed that they contain mostly CaO (about 70%-98%) and TiOx-SiO2 (about 2%-28%). These large size inclusions can significantly decrease the cleanliness of the cast steels (especially by addition of FeTi alloys for a final correction of the steel composition before casting) and their final mechanical properties. Processes of transformation of these and other non-metallic inclusions, which are present in the FeTi70R ferroalloy, were investigated after immersion of this ferroalloy into a melt of a Fe or a Fe-40Ni-20Cr steel. Moreover, the non-metallic inclusions were investigated in samples taken at different moments during the industrial production of a Fe-40Ni-20Cr steel alloyed with the FeTi70R ferroalloy. The inclusions existing during the production were then compared to those that evolved during the immersion of a FeTi70 alloy in the Fe-40Ni-20Cr melt. This helps to understand what type of inclusions that formed when FeTi70R alloys are added to a Fe-40Ni-20Cr melt and to estimate the harmful effect of these non-metallic inclusions on the quality of this steel grade during commercial production.
Place, publisher, year, edition, pages
Chinese Society for Metals , 2015. 797-800 p.
Alloy 825, Fe-40Ni-20Cr steel, FeTi70R alloy, Non-metallic inclusions, Alloy steel, Alloying, Ferroalloys, Inclusions, Iron compounds, Metals, Nickel, Steel metallurgy, Steelmaking, Transition metal alloys, Commercial productions, Composition analysis, Inclusion characteristics, Industrial production, Ni-20Cr, Steel compositions, Steel-making industries, Steel castings
IdentifiersURN: urn:nbn:se:kth:diva-194648ScopusID: 2-s2.0-84983158520OAI: oai:DiVA.org:kth-194648DiVA: diva2:1050552
6th International Congress on the Science and Technology of Steelmaking, ICS 2015, 12 May 2015 through 14 May 2015
QC 20161292016-11-292016-10-312016-11-29Bibliographically approved