Kinetic Discussion on Deoxidation and Desulphurization of Molten Steel with Calcium Treatment

In the current study, the effect of reoxidation on inclusions during calcium treatment was studied via adding Fe2O3 into a Al-killed molten steel at 1 min after the addition of calcium. The total oxygen (T.O.) content increased from 10 to 24 ppm just after the reoxidation occurred, while it finally decreased to 14 ppm since inclusions were floated to the top of the steel and absorbed by the formed slag layer. The increased T.O. favored the decomposition of CaS, especially for the heat with high sulfur contents. The vaporization of calcium, which leads to the decrease of calcium content, is the driving force for the evolution of inclusions from CaO-CaS-(Al2O3) to CaO-Al2O3-(CaS) due to the limited degree of reoxidation. The contact angle between inclusions and the molten steel increased with the increase of Al2O3 in calcium alumina, which favored the removal of inclusions. Increased sulfur content decreased the surface tension of molten steel, which led to remove less inclusions since the contact angle between inclusions and the molten steel was decreased. Thus, more inclusions were measured in heats with higher sulfur content.

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Castability of molten steel and cleanliness of slab for high strength low alloy steel without calcium treatment

Ironmaking & Steelmaking ◽

10.1179/1743281213y.0000000135 ◽

2013 ◽

Vol 41 (2) ◽

pp. 153-160 ◽

Cited By ~ 2

Author(s):

S. Zhao ◽

S. P. He ◽

G. J. Chen ◽

M. M. Peng ◽

Q. Wang

Keyword(s):

Alloy Steel ◽

Molten Steel ◽

High Strength ◽

Low Alloy Steel ◽

Calcium Treatment

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Effect of Calcium Treatment on Inclusions in H08A Welding Rod Steel

Metals ◽

10.3390/met11081227 ◽

2021 ◽

Vol 11 (8) ◽

pp. 1227

Author(s):

Fangjie Lan ◽

Changling Zhuang ◽

Changrong Li ◽

Guangkai Yang ◽

Hanjie Yao

Keyword(s):

Melting Point ◽

Molten Steel ◽

Calcium Aluminate ◽

Large Scale ◽

Energy Dispersive Spectrometer ◽

Calcium Content ◽

Calcium Treatment ◽

Inclusion Composition ◽

Metallic Inclusions ◽

Before And After

The effect of calcium treatment on inclusions in H08A welding rod steel was studied by industrial experiment and using thermodynamics theory. The effects of inclusion composition, morphology, quantity, and size in H08A welding rod steel before and after calcium treatment were studied by metallographic microscope, scanning electron microscope (SEM), and energy dispersive spectrometer (EDS). Thermodynamic studies show that the addition of calcium can form various forms of xCaO·yAl2O3, under the condition that the composition of molten steel remains unchanged, the control of calcium content is the key to generate low melting point calcium-aluminate complex non-metallic inclusions and improve the quality of molten steel. The production practice in steel plant shows that for welding rod steels, the calcium content in a suitable range can meet the requirements of calcium treatment. Effective calcium treatment can not only transform the high melting point Al2O3 inclusions into the low melting point complex non-metallic inclusions between 3CaO·Al2O3 and 12CaO·7Al2O3, but also make the original shape-diversified inclusions into the spherical calcium-aluminate complex non-metallic inclusions. Meanwhile, the total number of inclusions and large-scale inclusions in welding rod steel are reduced, and the inclusions tend to disperse in the steel, which is very conducive to the improvement of steel quality. The results show that the modification path of magnesium aluminate spinel in steel is as follows: Al2O3 → MgO-Al2O3 → MgO-CaO-Al2O3. In addition, calcium treatment can modify MgO-Al2O3 spinel in steel into liquid MgO-CaO-Al2O3 complex non-metallic inclusions with low melting point.

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Inclusion Control of Oil Drilling Steel SAE4137

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.581-582.861 ◽

2012 ◽

Vol 581-582 ◽

pp. 861-867

Author(s):

Liang Chen ◽

Tian Ming Chen ◽

Yong Chen ◽

Yao Xian Zeng ◽

Ping Fan Li

Keyword(s):

Oxygen Content ◽

Molten Steel ◽

Mechanical Performance ◽

Refining Process ◽

Control Technology ◽

Calcium Treatment ◽

Treatment Technology ◽

Oil Drilling ◽

Ladle Slag ◽

Inclusion Control

In consideration of inclusion control in smelting drilling steel SAE4137 by convert process, the software FACTSAGE is applied on the deoxidation technology, composition of ladle slag and calcium treatment technology. The tests show that the deoxidation technology is reasonable and the oxygen content of molten steel is not more than 5×10-6 and 3.2×10-6 on average. The inclusion of bar is less and like a ball. The effect of calcium treatment is good. The inclusion is transformed in refining process, the absorbing ability to inclusion of ladle slag is strong. The level of any type of inclusion is not more than 1.5. The mechanical performance of SAE4137 bar meets the requirements, and the inclusion control technology does not influence the mechanical performance of bars.

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Transient Evolution of Nonmetallic Inclusions During Calcium Treatment of Molten Steel

Metallurgical and Materials Transactions B ◽

10.1007/s11663-018-1289-5 ◽

2018 ◽

Vol 49 (4) ◽

pp. 1841-1859 ◽

Cited By ~ 11

Author(s):

Lifeng Zhang ◽

Yang Liu ◽

Ying Zhang ◽

Wen Yang ◽

Wei Chen

Keyword(s):

Molten Steel ◽

Nonmetallic Inclusions ◽

Calcium Treatment

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Research on the variation of the inclusion and sulfur content in Pipeline steel

Metallurgical Research & Technology ◽

10.1051/metal/2021010 ◽

2021 ◽

Vol 118 (2) ◽

pp. 214

Author(s):

Tongsheng Zhang ◽

Rensheng Li ◽

Wanlin Wang ◽

Shifan Dai ◽

Peisheng Lv ◽

...

Keyword(s):

Liquid Phase ◽

Sulfur Content ◽

Molten Steel ◽

Pipeline Steel ◽

Solidification Process ◽

Liquid Inclusion ◽

Calcium Sulfide ◽

Calcium Treatment ◽

Inclusions In Steel ◽

Good Agreement

Pipeline steel is widely used in various industries, and the sulfur content and inclusions in steel have a significant impact on performance, which determines whether the steel quality is qualified. The experiments were carried out to explore the sulfur content and inclusion evolution of pipeline steel which was deoxidized by Si–Mn–Al with “EAF-LF-VD-T-CC”. The samples of molten steel and slag were taken during the process of LF-VD-Tundish after EAF tapping. The kinetics model was established to simulate the desulfuration process of molten steel in actual production, obtaining a result which the error is within 3 ppm. It can be summarized that proper calcium treatment can transform the inclusion into a liquid inclusion, the value of [Ca] ranges from 25 to 45 ppm. Too high and lower calcium treatment can cause the compositions of inclusions to deviate from the liquid phase area, while too low calcium treatment will increase the overall size and density of the inclusions. In addition, the evolution of inclusion in steel at refining temperature and during solidification process was comprehensively calculated, considering all types of inclusions such as calcium oxide, magnesium oxide, aluminum oxide, calcium sulfide, spinel, calcium aluminate and liquid inclusion. The thermodynamic calculations are in good agreement with experimental results, which can predict the formation of the inclusions in Si–Mn–Al deoxidized pipeline steel.

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