| 1. |
- Bi, Yanyan, et al.
(author)
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Investigations of inclusions in ferrochromium alloys
- 2014
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In: Ironmaking & steelmaking. - 0301-9233 .- 1743-2812. ; 41:10, s. 756-762
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Journal article (peer-reviewed)abstract
- Ferrochromium alloys are commonly added during different stages of steelmaking processes according to the specific steel grade being produced. Depending upon the ferrochromium quality, the addition can also lead to a supply of deleterious inclusions to the liquid steel. Therefore, the number, size, morphology and composition of inclusions in LCFeCr and HCFeCr alloys were investigated. The alloy samples were first treated with electrolytic extraction, followed by filtration to gather the inclusions on a film filter. Thereafter, the characteristics of the inclusions and clusters were investigated in three dimensions by SEM in combination with energy dispersive spectroscopy. The results show that the main inclusion types found in LCFeCr alloys are different to those found in HCFeCr alloys. More specifically, the inclusions in LCFeCr alloys were found to consist of Si-Cr-O and Cr-O oxides as well as intermetallic Cr-Fe inclusions. Moreover, the inclusions in HCFeCr alloys were found to consist of Cr-Mn-S, Cr-C-N, Si-Al-Ca-Mg-O and Ca-O-P inclusions. Overall, the inclusions can be divided into two categories depending on the melting point. Furthermore, the possible transformation of different inclusions after their addition to the liquid steel is discussed.
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| 2. |
- Bi, Yanyan, et al.
(author)
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Three Dimensional Evaluations of REM Clusters in Stainless Steel
- 2014
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In: ISIJ International. - : Iron and Steel Institute of Japan. - 0915-1559 .- 1347-5460. ; 54:6, s. 1266-1273
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Journal article (peer-reviewed)abstract
- It is known that clusters in liquid steel have a harmful effect on the casting process and the quality of the final steel product. In this study, clusters. of rare earth metals (REM) were investigated in steel samples of a S30185 stainless steel grade from a pilot trial (PT, 250 kg) and from an industrial heat (IH, 100 t). Samples were taken from the liquid steel at different holding times after the addition of mischmetal. Thereafter, REM clusters collected on film filters after electrolytic extraction and filtration were investigated in three dimensions (3D) by SEM in combination with EDS. The morphology, composition, number and size of clusters in PT and IH steel samples were analyzed and compared as a function of holding time. It was found that typical clusters with regular and irregular inclusions were the main type of clusters (69%-98%) in all PT and IH steel samples. The composition of inclusions in clusters corresponded mostly to REM-oxides. The size of clusters that were observed in different samples varied mainly from 2 to 23 mu m. In addition, the size and number of most clusters in PT are larger than those in IH samples. Furthermore, the formation mechanisms and evolution of different type of REM clusters were discussed in both PT and IH heats.
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| 3. |
- Karasev, Andrey, et al.
(author)
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Estimation of non-metallic inclusions in industrial Ni based alloys 825
- 2017
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In: Steel Research International. - : Wiley. - 1611-3683 .- 1869-344X. ; 88:4
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Journal article (peer-reviewed)abstract
- It is well known that inclusions affect the properties of the steel and other alloys. The importance of understanding the behavior of the inclusions during production can never be overstated. This study has examined the main types of big size (>10μm) inclusions that exist in Ni-based Alloy at the end of ladle treatment and after casting during industrial production of Ni based Alloys 825. Sources, mechanisms of formation and behavior of different type large size inclusions in Alloy 825 are discussed based on 2 and 3D investigations of inclusion characteristics (such as, morphology, composition, size, and number) and thermodynamic considerations. The large size inclusions found can be divided in spherical (Type I and II) inclusions and in clusters (Type III-V). Type I-A inclusions (Al2O3-CaO-MgO) originate from the slag. Type I-B inclusions and Type II inclusions consist of CaO-Al2O3-MgO and Al2O3-TiO2-CaO, respectively. Both types originate from the FeTi70R alloy. Type III clusters (Al2O3-MgO-CaO) are formed during an Al deoxidation of the Ni-based alloy. Type IV clusters (Al2O3-TiO2-CaO) formed from small inclusions, which are precipitated in local zones which contain high Ti and Al levels. These clusters are transformed to Type III clusters over time in the ladle. Finally, Type V clusters are typical TiN clusters.
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| 4. |
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| 5. |
- Karasev, Andrey, et al.
(author)
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Three-dimensional investigation of large-size inclusions and clusters in steels by using the electrolytic extraction technique
- 2013
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In: AISTech 2013. - 9781935117339 ; , s. 1139-1145
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Conference paper (peer-reviewed)abstract
- It is well known that the non-metallic inclusions and clusters (especially, the large size inclusions and clusters) in steels have significant harmful effects on the mechanical properties of final products. Therefore, it is important to carry out a precise quantitative analysis of inclusion and cluster characteristics in metal samples at different stages of steel production. According to the obtained experimental results during the last years, it was found that the three-dimensional (3-D) investigation of inclusions and clusters on a film filter after electrolytic extraction of steel samples (EE) has a major advantageous in comparison to commonly used two-dimensional (2-D) observations on a polished cross section of metal samples. Experimental results focusing mainly on investigations of large size inclusions and clusters in different steels are discussed in this study.
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| 6. |
- Karasev, Andrey V., et al.
(author)
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Nitride Precipitation on Particles in Fe-10 mass % Ni Alloy Deoxidized with Ti, M (M=Mg, Zr and Ce) and Ti/M
- 2009
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In: ISIJ International. - : Iron and Steel Institute of Japan. - 0915-1559 .- 1347-5460. ; 49:2, s. 229-238
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Journal article (peer-reviewed)abstract
- The precipitation of nitrides on deoxidation particles in an Fe-10mass%Ni alloy containing 30 similar to 130 ppm O and 14 similar to 22 ppm N has been studied in the experiments where an alloy was deoxidized with Ti, M (M=Mg, Zr and Ce) and Ti/M at 1600 degrees C and then cooled to 1200 degrees C, followed by holding for 0 and 60 min before quenching. The total number of particles above 0.1 mu m remains almost constant except in Ti deoxidation, but the proportion of cubic particles which correspond to nitrides and oxide-nitrides increases during holding at 1200 degrees C in Ti, Zr, Ti/Mg and Ti/Zr deoxidations. In 0.05% (initial amount) Ti deoxidation, the number of TiN and TiN+TiOx particles increases during holding. In 0.03%Ti/0.1%Mg deoxidation, the number of TiOx-TiN particles decreases and the number of MgO-TiN and MgO-Ti(O, N) particles increases during holding due to the reduction of TiOx with soluble Mg. In 0.03%Ti/0.04%Zr deoxidation, the number of ZrO2 particles significantly decreases during holding due to the precipitation of TiN and ZrN on Zr oxides and formation of Zr(O, N)-Ti(O, N) particles. In the cases of Ti/0.08%Zr and Ti/0.12%Ce deoxidations, most of particles at 0 and 60 min of holding are ZrO2 and Zr(O, N) and Ce2O3 oxides, respectively, because the FeO-TiOx oxide in particles is reduced completely by dissolved Zr and Ce.
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| 7. |
- Kellner, Hans, 1989-, et al.
(author)
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Effect of the Stirring Mode on the Behavior of Al2O3–MgO Particles and Clusters during Ladle Treatment of Ni-based Alloy 825
- 2017
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In: Steel Research International. - Weinheim : Wiley-VCH Verlagsgesellschaft. - 1611-3683 .- 1869-344X. ; 87
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Journal article (peer-reviewed)abstract
- It is well known that inclusions affect the properties of alloys. Therefore, the importance of understanding what inclusions exist and how they behave cannot be overstated. This study has examined the behavior of Al2O3–MgO particles and clusters in the melt during the ladle treatment of Alloy 825, who is a Ni-based Alloy. The effect of different stirring directions of electromagnetic stirring in combination with gas stirring is discussed based on three-dimensional investigations of the clustered particles. More specifically, the composition, size, and number of particles and clusters are determined after electrolytic extraction of metal samples by using SEM in combination with EDS. The results show that the agglomeration of Al2O3–MgO particles in the melt is faster for an upward induction stirring combined with a gas stirring in comparison to a downward stirring combined with a gas stirring. However, the total removal of clusters from the melt is more effective when using a downward induction stirring compared to when using an upward induction stirring, especially for large size clusters (>11.2 mm). The effect of the different stirring modes on the behavior of the Al2O3–MgO particles and clusters in the melt for the ladle treatment experiments agree with the theoretical predictions based on Stokes’, Brownian, and Turbulent collisions.
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| 8. |
- Kellner, Hans, et al.
(author)
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TiN Particles and Clusters during Ladle Treatments of Ni-based Alloy 825 using Different Stirring Modes
- 2018
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In: ISIJ International. - : IRON STEEL INST JAPAN KEIDANREN KAIKAN. - 0915-1559 .- 1347-5460. ; 58:2, s. 292-298
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Journal article (peer-reviewed)abstract
- Today, titanium is often used in steelmaking not only for deoxidation but also for micro-alloying and alloying for a wide range of steel grades. Therefore, many studies are focused on investigations on the formation and behavior of Ti-containing non-metallic inclusions (such as oxides, nitrides and carbides) during production of different Ti-containing steels and their effect on final steel properties. This study has examined the behavior of TiN clusters and particles in the melt during the ladle treatment of Alloy 825 containing up to 1.2 wt% of Ti. The industrial trials were performed at the end of the ladle treatment by using argon gas in combination with electromagnetic stirring using an upwards or a downwards stirring direction. Metal samples were taken before and after ladle treatment to enable three-dimensional investigations of non-metallic inclusions and clusters. The composition, size and number of particles and clusters were determined after electrolytic extraction of the metal samples by using SEM in combination with EDS. It was found that agglomerations of TiN clusters and particles in the melt are faster during an upwards stirring in comparison to a downwards stirring. However, the removal of clusters from the melt is more effective when using a downwards stirring direction compared to when using an upwards stirring in combination with gas stirring. It was also found that the Turbulent collision is the dominant factor for the agglomeration of TiN particles in the melt.
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| 9. |
- Malmberg, Kristofer, et al.
(author)
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Influence of final stirring treatment on inclusion number in tool steel
- 2013
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In: Ironmaking & steelmaking. - 0301-9233 .- 1743-2812. ; 40:6, s. 407-412
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Journal article (peer-reviewed)abstract
- The focus was to study the elimination of non-metallic inclusions during the final part of the ladle refining of tool steel (AISI H13). More specifically, the final stirring treatment in a ladle before casting was modified to study how the number of inclusions could be decreased. The following three stirring treatments were tested: a conventional induction stirring with a 650 A current for 20 min, a short induction stirring with a 650 A current during 10 min, and a combined gas and induction stirring during 20 min (no open eye and a 600 A current). Steel samples were collected from the ladle before and after the final stirring period of the ladle treatment. Thereafter, the numbers of inclusions in steel samples were determined using a light optical microscope based on a classification according to the Swedish standard SS111116 (JK Scale II). Overall, the results showed that a combined gas and induction stirrings was the most efficient way of decreasing the number of DM, DH and DP inclusions. The decrease in the inclusion number in four heats was the following for the different size classes for a combined stirring procedure: 15-40% for DM type inclusions, 30-61% for DH type inclusions and 50-100% for DP inclusions. In addition, it should be mentioned that a stirring practice with induction stirring during 10 min resulted in a 67-100% decrease in the DH type inclusions. However, the results for a combined stirring case for DH type inclusions were more stable than those for a shorter induction stirring time.
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| 10. |
- Wang, Yong, et al.
(author)
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Comparison of Nonmetallic Inclusion Characteristics in Metal Samples Using 2D and 3D Methods
- 2020
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In: Steel Research International. - : Wiley. - 1611-3683 .- 1869-344X. ; 91:7, s. 1900669-
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Journal article (peer-reviewed)abstract
- The characteristics of different shapes of nonmetallic inclusions (NMIs) aredetermined using different methods. In this respect, various shapes of NMIs,including spherical, octahedral, elongated, bar-like, plate-like, polyhedral, andirregular inclusions, are observed in different steels and ferroalloys. The inclu-sions are investigated using three methods: 1) 2D investigations on a polishedcross section (2D method); 2) 3D investigations on afilmfilter after electrolyticextraction andfiltration (EE method); and 3) 3D investigations on a metal surfaceafter electrolytic extraction (MS method). In addition, scanning electron micro-scopy (SEM) with an energy-dispersive spectrometer (EDS) is used for thedetermination of the chemical composition of inclusions. The advantages andlimitations of different methods for investigations of different shaped inclusionsare discussed. The results show that the 2D method is less precise to detectthe morphology, size, and number of inclusions; however, the EE and MSmethods are used to determine a more accurate morphology. Furthermore, theMS method is found to be more advantageous in detecting large-sized inclusions.This study also shows that the results on both thefilmfilter and metal surfaceshould be grouped together to obtain more comprehensive information of theinclusion characteristics.
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