Inclusion Characterization and Formation Mechanisms in Spring Steel Deoxidized by Silicon

Lyu, Sha; Ma, Xiaodong; Huang, Zongze; Yao, Zan; Lee, Hae-Geon; Wang, Geoff; Zou, Jin; Zhao, Baojun

doi:10.1007/s11663-019-01505-3

Cited by 18 publications

(7 citation statements)

References 56 publications

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“…Relevant literature shows that MnO-containing spinel would only be stable in steel containing 6 pct Mn if the concentration of dissolved Al were lower than approximately 170 ppm, much lower than the actual Al concentration in these grades (wt pct Al > 0.5). The conclusion is that the MnO concentration in oxide inclusions would be zero or negligible (although Mn-containing sulfides can form during solidification, as shown later) [17]. Therefore, there may be a small amount of MnO in the molten steel without being observed.…”

Section: Lf Startmentioning

confidence: 84%

Evolution of Non-Metallic Inclusions in 27SiMn Steel

Zhang

Liu

et al. 2022

Metals

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To study the evolution of non-metallic inclusions in 27SiMn steel, the 27SiMn steel produced using the LD-LF-CCM process was sampled in various stages in a steel factory. The evolutionary behavior of inclusion in various processes was systematically analyzed by scanning electron microscopy (SEM-EDS), and the total oxygen content and nitrogen content in 27SiMn steel were measured at various production steps. On the basis of the calcium treatment for 27SiMn steel, the equilibrium reactions for Ca-Al were calculated according to the thermodynamic equilibrium model. The results showed that the types of inclusions at the start of LF stations are mainly Al2O3-FeO and MnS-Al2O3. Before calcium treatment, the inclusions are mostly calcium aluminate and CaO-MgO-Al2O3. Compared with the process after soft blowing, the number density of inclusions in tundish increased by 77.88%, possibly due to secondary oxidation. From the soft blowing process to the continuous casting round billet, the inclusions translate into spherical CaO-MgO-Al2O3-SiO2, and a large number of CaS were observed. One part of the CaS precipitated separately, the other part was semi-wrapped with the composite inclusions. At the same time, calcium treatment increases the number density, mean diameter, and the area fraction of inclusions. The mass fraction of T.O. (total oxygen content) increased significantly after soft blowing, and the N content increased greatly from station to tundish. The change trend of N content in steel was basically consistent with that of T.O. content. It was necessary to prevent the secondary oxidation of molten steel during calcium treatment and the casting process. When the liquidus temperature of liquid steel is 1873 K, w[Al] = 0.022%, and w[Ca] in steel is controlled between 1.085 × 10−6 and 4.986 × 10−6, the Al2O3 inclusion degeneration effect is good.

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Section: Lf Startmentioning

confidence: 84%

Evolution of Non-Metallic Inclusions in 27SiMn Steel

Zhang

Liu

et al. 2022

Metals

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“…An improved quenching technique was developed with the application of electron probe microanalysis (EPMA) [17][18][19][20][21][22][23]29]. In this technique, pure oxides or carbonates were weighed and mixed according to the experimental plan and pelletized.…”

Section: Liquidus Temperaturementioning

confidence: 99%

“…The phase equilibrium in the system CaO-MgO-Al 2 O 3 -SiO 2 has been studied extensively by many researchers [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23] and the phase diagrams were presented in different forms. Muan et al [24] and the Slag Atlas [25] collected and summarised most of the existing data.…”

Section: Introductionmentioning

confidence: 99%

Phase Equilibrium Studies of the CaO-MgO-Al2O3-SiO2 System for Iron Blast Furnace Slag: A Review

Liao

Qing

Zhao

2023

Metals

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More and larger blast furnaces have been constructed for ironmaking across the world in recent years due to the advantages of high productivity, high energy efficiency and low cost. Slag plays important role in a blast furnace to produce high-quality hot metal and maintain smooth operations. Liquidus temperatures are the essential information of the slag to avoid the formation of the solid phase during the ironmaking process and slag tapping. The principal components of the iron blast furnace slags can be described by the system CaO-MgO-Al2O3-SiO2. With the significant changes in the raw materials and different requirements of the blast furnace operations, phase equilibria in this slag system have been extensively investigated from different directions. Phase diagrams were presented in various pseudo-ternary and pseudo-binary forms to meet the requirements of wide applications. Reliable thermodynamic modelling is the target of the researchers which can predict accurate liquidus temperatures of the slag. Development of the reliable thermodynamic modelling relies on systematic and accurate experimental data including liquidus temperatures and compositions of the solid solutions. Experimental data on the phase equilibria of the system CaO-MgO-Al2O3-SiO2 are summarised and compared with the thermodynamic predictions which can provide systematic information for the researchers and blast furnace operators.

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“…The top slag used in the spring steel refining process is the CaO-SiO 2 -Al 2 O 3 -MgO slag system. Many scholars [1,2,[37][38][39] have studied that the melting point of inclusion is affected by the content of Al 2 O 3 and the basicity of refining slag. Wang X H [39] found that the Al 2 O 3 content in the slag less than 8% is beneficial to obtain the inclusion with the low-melting point.…”

Section: The Optimum Composition Of Top Slag To Control the Inclusionsmentioning

confidence: 99%

“…Si-killed oil tempered wire steel is used widely in the automotive industry for many different applications, such as suspension spring [1,2] and valve spring [3,4], which require high strength and superior fatigue resistance [5,6]. Springs are subjected to multiple actions during their long-time service, including tension [7,8], impact [9,10], torsion [11], and corrosion [12], etc.…”

Section: Introductionmentioning

confidence: 99%

Behaviour of oxide inclusions and sulphur in ‘two-stage basicity control’ refining method of Si-killed spring steel

Wang

Han

Zhang

et al. 2020

Ironmaking & Steelmaking

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A 'two-stage basicity control' refining method was carried out that high basicity (R > 1.5) top slag was used in the LF refining and then low basicity (R = 0.8-1.0, Al 2 O 3 < 6%) top slag was used in VD refining. This method can obtain inclusions with better deformability and make the top slag have good desulphurization ability. The average sulphur removal percentage of the refining is 47.22%. There were mainly three types of inclusions classified as Al 2 O 3 -SiO 2 , CaO-Al 2 O 3 -SiO 2 , and MgO-CaO-Al 2 O 3 -SiO 2 inclusions in the LF refining. In the VD refining, the number of Al 2 O 3 -SiO 2 and CaO-Al 2 O 3 -SiO 2 inclusions reduced obviously. The main type of inclusions was MgO-CaO-Al 2 O 3 -SiO 2 and their melting points reduced from about 1873 K to less than 1673 K during the VD refining. The results of thermodynamic calculations show that the mass fraction of [Al] should be controlled less than 20×10 −6 to obtain low-melting point inclusions (<1673 K).

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Inclusion Characterization and Formation Mechanisms in Spring Steel Deoxidized by Silicon

Cited by 18 publications

References 56 publications

Evolution of Non-Metallic Inclusions in 27SiMn Steel

Evolution of Non-Metallic Inclusions in 27SiMn Steel

Phase Equilibrium Studies of the CaO-MgO-Al2O3-SiO2 System for Iron Blast Furnace Slag: A Review

Behaviour of oxide inclusions and sulphur in ‘two-stage basicity control’ refining method of Si-killed spring steel

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