Evolution Mechanisms of MgO·Al&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt; Inclusions by Cerium in Spring Steel Used in Fasteners of High-speed Railway

Wang, Li Jun; Liu, Yan Qiang; Wang, Qi; Chou, Kang Ju

doi:10.2355/isijinternational.55.970

Cited by 68 publications

(49 citation statements)

References 9 publications

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“…Some researchers have investigated that rare earth elements can effectively transform hard oxides and elongated sulfides into low‐hardness rare earth oxides or rare earth oxy‐sulfides. Some researchers have carried out studies on the modification of MgO · Al 2 O 3 inclusion by rare earth elements in laboratory experiments. However, few detailed studies have been performed on the effect of cerium on the behavior of inclusions in H13 steel by industrial trials, especially, the behavior of multilayer carbonitrides.…”

Section: Introductionmentioning

confidence: 99%

Effect of Cerium on the Behavior of Inclusions in H13 Steel

Huang

Cheng

et al. 2018

steel research int.

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The modification mechanism of cerium (Ce) on oxides and multilayer carbontrides in H13 steel is investigated by industrial trials and thermodynamic calculations. The morphology, composition, and size of inclusions are analyzed by scanning electron microscopy and energy dispersive spectroscopy. The main inclusions in H13 steel without Ce content in the molten steel are MgAl2O4 spinel inclusions and multilayer carbonitrides. The carbonitrides have a multilayer structure in which MgAl2O4 acts as the nucleation core and the second layer is (Ti, V)(C, N). As the cerium content in molten steel increases from 0 to 0.03 wt%, the MgAl2O4 is effectively modified into cerium oxide (Ce–O) and cerium oxy‐sulfide (Ce–O–S), and the evolutionary process is as follows: MgAl2O4 → CeAlO3 → Ce–O and Ce–O–S. Likewise, the structure of multilayer carbonitrides in the H13 steel also changed. The MgAl2O4 and CeAlO3 act as heterogeneous nucleation cores of multilayer carbonitrides. However, Ce–O and Ce–O–S can effectively inhibit the heterogeneous nucleation of carbonitrides. The number density of large‐size carbontrides is remarkably reduced with increasing Ce content. A prediction model of optimum Ce content in molten steel is built, which has remarkable agreement with the experimental observations.

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Section: Introductionmentioning

confidence: 99%

Effect of Cerium on the Behavior of Inclusions in H13 Steel

Huang

Cheng

et al. 2018

steel research int.

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“…The content of each element in the steel discussed in this section is total content, and the calculation results are shown in Figure 8. Huang et al [7,9] and Wang et al [8] reported that the sequence of Ce-modified spinel is spinel → CeAlO 3 → Ce 2 O 3 → Ce 2 O 2 S or spinel → Ce 2 O 3 → Ce 2 O 2 S. However, no Ce 2 O 3 inclusions were found in the present experimental steel. After comparing the experimental conditions, it was found that the contents of Al and S in the steel were different.…”

Section: Ce Content Required For Complete Modification Of Spinel Inclmentioning

confidence: 49%

“…2 After Ce treatment, spinel can be preferentially transformed to CeAlO 3 . After a while, the resulting CeAlO 3 product layer will be transformed to Ce 2 O 2 S. The first-step reaction was considered to be difficult to perform completely because we observed some inclusions with a three-layer structure in the experiment, as shown in Huang et al [7,9] and Wang et al [8] reported that the sequence of Ce-modified spinel is spinel → CeAlO3 → Ce2O3 → Ce2O2S or spinel → Ce2O3 → Ce2O2S. However, no Ce2O3 inclusions were found in the present experimental steel.…”

Section: Thermodynamics Analysismentioning

confidence: 75%

“…Table 1 shows the compositions of raw materials, including pure iron, MnFe alloy, Al wire, NiMg alloy, and CeFe alloy. Wang et al [8] respectively studied the modification behavior of Ce on inclusions in drill steel and high-speed railway steel, and the transformation mechanism of spinel to Ce2O3 and Ce2O2S was described. However, there are relatively few reports on rare earth modified spinel inclusions.…”

Section: Methodsmentioning

confidence: 99%

“…The rare earth element Ce has a good modification effect on the spinel [7][8][9], which can modify the hard oxide inclusions into rare earth inclusions with a soft hardness [10]. Huang et al [7,9] Metals 2019, 9, 804 2 of 13 and Wang et al [8] respectively studied the modification behavior of Ce on inclusions in drill steel and high-speed railway steel, and the transformation mechanism of spinel to Ce 2 O 3 and Ce 2 O 2 S was described. However, there are relatively few reports on rare earth modified spinel inclusions.…”

Section: Introductionmentioning

confidence: 99%

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Modification Mechanism of Spinel Inclusions in Medium Manganese Steel with Rare Earth Treatment

Liu

2019

Metals

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In aluminum deoxidized medium manganese steel, spinel inclusions are easily to form during refining, and such inclusions will deteriorate the toughness of the medium manganese steel. Rare earth inclusions have a smaller hardness, and their thermal expansion coefficients are similar to that of steel. They can avoid large stress concentrations around inclusions during the heat treatment of steel, which is beneficial for improving the toughness of steel. Therefore, rare earth Ce is usually used to modify spinel inclusions in steel. In order to clarify the modification mechanism of spinel inclusions in medium manganese steel with Ce treatment, high-temperature simulation experiments were carried out. Samples were taken step by step during the experimental steel smelting process, and the inclusions in the samples were analyzed by SEM-EDS. Finally, the experimental results were discussed and analyzed in combination with thermodynamic calculations. The results show that after Ce treatment, the amount of inclusions decrease, the inclusion size is basically less than 5 μm, and the spinel inclusions are transformed into rare earth inclusions. After Ce addition, Mn and Mg in the spinel inclusions are first replaced by Ce, and the spinel structure is destroyed to form CeAlO3. When the O content in the steel is low, S in the steel will replace the O in the inclusion, and CeAlO3 and spinel inclusions will be transformed into Ce2O2S. By measuring the total oxygen content of the steel, the total Ce content required for complete modification of spinel inclusions can be obtained. Finally, the critical conditions for the formation and transformation of inclusions in the Fe-Mn-Al-Mg-Ce-O-S system at 1873K were obtained according to thermodynamic calculations.

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Effect of Rare Earth–Magnesium Alloy on Inclusion Evolution in Industrial Production of Die Steel

Xing

Geng

Chen

et al. 2019

steel research int.

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Rare earth metals and magnesium are important purifying elements in steel. However, most scholars mainly focused on the cleanliness of molten steel by adding single rare earth or adding single magnesium. There are few reports on the simultaneous addition of rare earth and magnesium metals to steel. In this paper, rare earth-magnesium alloy is added to a hot work die steel in industrial production. Combined with thermodynamic calculation, the effect of rare earth-magnesium alloy on the evolution of inclusions was studied. The results show that composite inclusions of Ce 2 O 2 S and CeS attached or wrapped by MgO are formed after adding rare earth-magnesium alloy. With the help of low-density MgO, the composite inclusions containing highdensity Ce inclusions are promoted to float up. Thermodynamic calculation indicates that the addition of magnesium changes the formation tendency of rare earth inclusions. With the increase of magnesium content in steel, the stability area of Ce inclusions will move from the Ce 2 O 2 S stability area slightly close to the Ce 2 O 3 stability area to the direction of the CeS stability area, which will improve further the desulfurization ability. The thermodynamic analysis is in good agreement with the test results.

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Evolution Mechanisms of MgO·Al<sub>2</sub>O<sub>3</sub> Inclusions by Cerium in Spring Steel Used in Fasteners of High-speed Railway

Cited by 68 publications

References 9 publications

Effect of Cerium on the Behavior of Inclusions in H13 Steel

Effect of Cerium on the Behavior of Inclusions in H13 Steel

Modification Mechanism of Spinel Inclusions in Medium Manganese Steel with Rare Earth Treatment

Effect of Rare Earth–Magnesium Alloy on Inclusion Evolution in Industrial Production of Die Steel

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