Under what circumstances they are likely to form? Are they stable inclusions or they get converted to some other phase by reacting with steel or oxides in steel? Any literature on the same would be helpful.
I hope this link would help you:
https://scholarsmine.mst.edu/cgi/viewcontent.cgi?article=6422&context=masters_theses
Good luck
Inclusion control plays a decisive role on the microstructure evolution and mechanical properties of steel articles, which determines the cleanliness level of liquid steel we process. Sulphide inclusions are the one such important class of inclusions that are identified in the category of non-metallics. Deoxidation of various grades of steels with aluminum (Al) is a common practice in steel making. Surprisingly, the deoxidizer aluminum is a weak sulphide former in steel practice, as can be seen from the Ellingham diagram (cf. Fig. A). The most important sulphide inclusion form of aluminum is aluminum sulphide (Al2S3), which usually forms when a steel is deoxidized with a large excess of aluminum. This inclusion phase Al2S3 exhibits polymorphism. The three different polymorphic forms of Al2S3 are 𝛼- Al2S3, 𝛾- Al2S3, and 𝛽- Al2S3. The well-accepted studies of Karmazin indicated as, during the deoxidation of steel with aluminum directly results in the precipitation of Al2S3 inclusion as the first sulphide constituent, because the high-temperature crystalline form 𝛾-Al2S3 is isostructural with 𝛼- Al2O3 (Corundum) and wets it readily. Appreciable growth of liquid Al2S3 - Al2O3 particles therefore takes place before any MnS-FeS starts to precipitate, and further sulphide precipitation occurs through absorption of iron-manganese sulphides by the liquid particles of Al2S3 - Al2O3. Such a condition leads to the formation of massive complex sulphide inclusions (designated as Type III), as can be seen in wrought steels (cf. Fig. B). It is of interest to note that the metastable crystalline form 𝛽- Al2S3 is said to be stabilized by the solute carbon in steel. So, this sulfide may be a carbosulphide. Additionally, microscopy studies found that the Al2S3 (melting point ~1130°C) inclusion is a multiphase inclusion which can be formed by co-existing with FeS and MnS phases. The high-temperature stability of such complex sulfide phase assemblage is an interesting aspect and can be well-evident from the FeS- Al2S3 phase diagram (cf. Fig. C). Much more information on the decisive role of non-metallic inclusions on the properties of cast steels has been provided elsewhere [Roland Kiessling, 1968; Vanhorn, 1953].
References:
1. Kiessling, Roland, and Nils Lange. "Non-metallic inclusions in steel." (1968).
2. Case, Samuel Lewis, and Kent Robertson Van Horn. Aluminum in iron and steel. Vol. 1. Published for the Engineering Foundation by Wiley, 1953.
- Badges
- Science topic
- Similar topics
- Physical Sciences
- Materials Science
- Materials
- Inorganic Materials
- Metals
- Alloys
- Steel