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Metals 2019, 9(1), 74;

Modification of Non-Metallic Inclusions in Stainless Steel by Addition of CaSi

KTH Royal Institute of Technology, Brinellvägen 23, Stockholm 10044, Sweden
Sandvik Materials Technology AB, Sandviken 81181, Sweden
Author to whom correspondence should be addressed.
Received: 10 December 2018 / Revised: 7 January 2019 / Accepted: 8 January 2019 / Published: 12 January 2019
(This article belongs to the Special Issue Manufacturing and Application of Stainless Steels)
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The focus of this study involved comparative investigations of non-metallic inclusions in 316L stainless steel bars without and with Ca treatments. The inclusions were extracted by using electrolytic extraction (EE). After that, the characteristics of the inclusions, such as morphology, size, number, and composition, were investigated by using a scanning electron microscope (SEM) in combination with an energy dispersive X-ray spectroscopy (EDS). The following four types of inclusions were observed in 316L steels: (1) Elongated MnS (Type I), (2) MnS with hard oxide cores (Type II), (3) Undeformed irregular oxides (Type III), and (4) Elongated oxides with a hard oxide core (Type IV). In the reference sample, only a small amount of the Type III oxides (Al2O3–MgO–MnO–TiOx) existed. However, in Ca-treated 316L steel, about 46% of the observed inclusions were oxide inclusions (Types III and IV) correlated to gehlenite and to a mixture of gehlenite and anorthite, which are favorable for the machinability of steel. Furthermore, untransformed oxide cores (Al2O3–MgO–MnO) were also found in the inclusions of Type IV. The mechanism leading to different morphologies of oxide inclusions is also discussed. View Full-Text
Keywords: stainless steel; Ca treatment; non-metallic inclusion; electrolytic extraction stainless steel; Ca treatment; non-metallic inclusion; electrolytic extraction

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Du, H.; Karasev, A.; Sundqvist, O.; Jönsson, P.G. Modification of Non-Metallic Inclusions in Stainless Steel by Addition of CaSi. Metals 2019, 9, 74.

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