Thermodynamics and Agglomeration Behavior on Spinel Inclusion in Al-Deoxidized Steel Coupling with Mg Treatment

Lei, Chong; Wang, Guocheng; Yuan, Xinghu; Jin, Pengliang; Sridhar, Seetharaman

doi:10.3390/met9080900

Cited by 21 publications

(10 citation statements)

References 35 publications

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“…In the present study, Mg oxidation has been applied to control the existing forms of Ti within inclusions/precipitates in steel. Mg has a stronger affinity with oxygen than Al and Ti [30,31]. Thus, Al 2 O 3 and Ti 2 O 3 inclusions are easy to be reduced by Mg in steel.…”

Section: Effect Of Mg Content On the Behavior Of Ti-containing Inclusmentioning

confidence: 99%

Mechanism of Improving Heat-Affected Zone Toughness of Steel Plate with Mg Deoxidation after High-Heat-Input Welding

Yang

Park

et al. 2020

Metals

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In the present study, the mechanism of improving HAZ toughness of steel plate with Mg deoxidation after the simulated welding with the heat input of 400 kJ/cm was investigated through in situ observation, characterization with SEM-EDS and TEM-EDS, and thermodynamic calculation. It was found that intragranular acicular ferrite (IAF) and polygonal ferrite (PF) contributed to the improvements of HAZ toughness in steels with Mg deoxidation. With the increase of Mg content in steel, the oxide in micron size inclusion was firstly changed to MgO-Ti2O3, then to MgO with the further increase of Mg content in steel. The formation of nanoscale TiN particles was promoted more obviously with the higher Mg content in the steel. The growth rates of austenite grains at the high-temperature stage (1400~1250 °C) during the HAZ thermal cycle of steels with conventional Al deoxidation and Mg deoxidation containing 0.0027 and 0.0099 wt% Mg were 10.55, 0.89, 0.01 μm/s, respectively. It was indicated that nanoscale TiN particles formed in steel with Mg deoxidation were effective to inhibit the growth of austenite grain. The excellent HAZ toughness of steel plates after welding with a heat input of 400 kJ/cm could be obtained by control of the Mg content in steel to selectively promote the formation of IAF or retard the growth of austenite grain.

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Section: Effect Of Mg Content On the Behavior Of Ti-containing Inclusmentioning

confidence: 99%

Mechanism of Improving Heat-Affected Zone Toughness of Steel Plate with Mg Deoxidation after High-Heat-Input Welding

Yang

Park

et al. 2020

Metals

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“…The size of type M inclusions increases obviously, and there are few pure MgO·Al 2 O 3 spinel inclusions. As the precipitation temperature of MnS is lower than the solidus temperature, MgO·Al 2 O 3 can provide heterogeneous nucleation sites for MnS during the solidification process, [ 51 ] so sulfides tend to exist as complex inclusions in slab. Similarly, the complex inclusions with MgO or MgO·Al 2 O 3 as the core covered by TiN are also formed in the slab, which can be explained by the concept of lattice mismatch.…”

Section: Resultsmentioning

confidence: 99%

Characteristics and Evolution of Inclusions in Ti‐Bearing Peritectic Steel with Mg Treatment

Cai

Deng

Yang

et al. 2021

steel research int.

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Mg treatment is conducted in the production of peritectic steel, which greatly reduces the average value of incidence of transverse corner crack in continuous casting slab from 3.10% to 1.06% by 65.8%. In the industrial experiment with the stages of Ar station, before magnesium treatment, after magnesium treatment, and in the slab, the maximum Mg content is 30 ppm after Mg treatment. A large number of Mg containing complex inclusions are formed, and most of Al2O3 are transformed into MgO·Al2O3. In the inclusions, the content of MgO significantly increases from 3.58% to 27.2%. The number density of Mg containing inclusions increases from 45.2 to 168 mm−2. The oxide inclusions smaller than 2 μm account for more than 90%, indicating that Mg treatment can promote the refinement of inclusions. In the slab, most oxide inclusions are transformed into the complex inclusions with Mg containing oxides as the core covered by TiN and sulfide precipitates. These complex inclusions with a size above 1 μm can effectively promote the nucleation and growth of intragranular ferrite to prevent the generation of transverse corner cracks.

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“…where, (hkl) s is a low-index crystal face on the substrate phase MgAl 2 31) listed the parameters for the calculation and the calculated mismatch is 7.940%. The heterogeneous nucleation is more likely to be formed as the mismatch between the two phase is small.…”

Section: Thermodynamics Of Inclusion Formationmentioning

confidence: 99%

Thermodynamic Formation and Three-dimensional Characterization of MnS–MgAl<sub>2</sub>O<sub>4</sub> Composite Inclusions in Steel

Meng

et al. 2023

ISIJ Int.

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The distribution and morphology of inclusions in steel have an important effect on the quality of steel. It has been proved that the oxide inclusions can be modified into small and dispersed spinel inclusions by adding proper amount of Mg in steel. The MnS-MgAl 2 O 4 composite inclusions are formed with the core of MgAl 2 O 4 inclusions during the solidification process of molten steel, which has deforming ability and can improve the properties of materials steel. However, the investigation of the control of the composite inclusions is limited by the lack of understanding structure of the inclusions. In this study, the Mg treated steel samples were prepared by induction furnace in this study. In the experiment, SEM-EDS was used to characterize the samples, and thermodynamic calculations were used to describe the evolution mechanism of inclusions and MnS-MgAl 2 O 4 composite inclusions formed in steel samples with different Mg contents. The atomic mismatch calculated between MnS and MgAl 2 O 4 proves that they can nucleate effectively. The threedimensional (3D) morphology of the composite inclusion of MnS-MgAl 2 O 4 in steel samples were observed by using the X-ray Micro-CT in the beamline of BL16U2 at Shanghai Synchrotron Radiation Facility (SSRF). It is proved that MnS and MgAl 2 O 4 phases exist in the form of coassociated, which is valuable for the control of composite inclusions in steel. The current work provide a powerful method to analyze the detailed structure of the composite inclusions in the steel.

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Thermodynamics and Agglomeration Behavior on Spinel Inclusion in Al-Deoxidized Steel Coupling with Mg Treatment

Cited by 21 publications

References 35 publications

Mechanism of Improving Heat-Affected Zone Toughness of Steel Plate with Mg Deoxidation after High-Heat-Input Welding

Mechanism of Improving Heat-Affected Zone Toughness of Steel Plate with Mg Deoxidation after High-Heat-Input Welding

Characteristics and Evolution of Inclusions in Ti‐Bearing Peritectic Steel with Mg Treatment

Thermodynamic Formation and Three-dimensional Characterization of MnS–MgAl<sub>2</sub>O<sub>4</sub> Composite Inclusions in Steel

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