Effect of reoxidation on inclusions in steel during calcium treatment

2019 ◽  
Vol 116 (2) ◽  
pp. 206 ◽  
Author(s):  
Ming Li ◽  
Yang Liu ◽  
Lifeng Zhang
Keyword(s):  
Contact Angle ◽  
Sulfur Content ◽  
Molten Steel ◽  
Driving Force ◽  
Calcium Content ◽  
Slag Layer ◽  
Calcium Treatment ◽  
Total Oxygen ◽  
Limited Degree ◽  
Inclusions In Steel

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.

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

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.

scholarly journals Effect of Calcium Treatment on Inclusions in H08A Welding Rod Steel

Metals ◽  
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.

Effect of Refining Slag on the Inclusions of Hard Wire Steel during Melting Process

2011 ◽  
Vol 217-218 ◽  
pp. 1174-1179
Author(s):  
Yang Li ◽  
Zhou Hua Jiang ◽  
Shi You Yin ◽  
Ying Zhuang ◽  
Ming Li
Keyword(s):  
Ternary Phase Diagram ◽  
Melting Process ◽  
Melting Zone ◽  
Refining Slag ◽  
Total Oxygen ◽  
Deformation Ability ◽  
Inclusion Shape ◽  
Wire Steel ◽  
Al2o3 Inclusion ◽  
Inclusions In Steel

The effect of the refining slag composition on the total oxygen content and inclusions in steel was investigated in 100 t UHP Electric Furnace – LF – Billet CC process. The test steel was 77B hard wire steel and Si-Mn alloy was used as the deoxidizer. Three types slag were used in the industrial tests, which including CaO-CaF2, CaO-CaF2 adding CaC and CaO-Al2O3 refining slag. The results shown that the lowest total oxygen contents of rolled bar can be gained using the CaO-CaF2 refining slag adding CaC, which is 0.0036%, while the total oxygen contents of rolled bar using CaO-Al2O3 refining slag is higher a little than the heats using CaO-CaF2 refining slag. The CaO-SiO2 and CaO-Al2O3-SiO2 compound inclusions with the size of about 5 μm are the main inclusions in the heats refining by the CaO-CaF2 refining slag in the rolled bar, but the pure, indeformable Al2O3 inclusion can also be found with the size of about 10 μm. The CaO-Al2O3-SiO2 and Al2O3-SiO2-MnO compound inclusions are the main inclusions in the heats refining by the CaO-CaF2-CaC refining slag, but most of the inclusion shape is irregular with bigger size of about 10 μm. Similar with the heat using CaO-CaF2 refining slag, the pure Al2O3 inclusion with edge angle can be found in the rolled bar. The inclusions in the rolled bar treated by CaO-Al2O3 refining slag are CaO-Al2O3-SiO2 compound inclusions, most of which are nearly globular shape with the relative small size of about 5 μm. All of the inclusions in rolled bar lie on the low melting zone in the CaO-Al2O3-SiO2 ternary phase diagram in the heats using CaO-Al2O3 refining slag. The similar condition appeared on the most of the inclusions in the heats using CaO-CaF2 and CaO-CaF2 refining slag adding CaC, while part of which are lied on the high melting zone. Therefore, considering of the plastic deformation ability, the CaO-Al2O3 refining slag is the best slag for the melting process of hard wire steel.

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

2013 ◽  
pp. 395-399
Author(s):  
Haiyan Tang ◽  
Tongbo Zhang ◽  
Jingshe Li ◽  
Yanqi Song
Keyword(s):  
Molten Steel ◽  
Calcium Treatment

Thermodynamics and transient behavior of the inclusion in Si deoxidized stainless steel for high-grade plate

2019 ◽  
Vol 116 (6) ◽  
pp. 612
Author(s):  
Wanlin Wang ◽  
Liwen Xue ◽  
Tongsheng Zhang ◽  
Lejun Zhou ◽  
Daoyuan Huang ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Stainless Steels ◽  
Energy Dispersive Spectrometer ◽  
Transient Behavior ◽  
Field Energy ◽  
Liquid Region ◽  
High Grade ◽  
Calcium Treatment ◽  
Solidification Temperature ◽  
Inclusions In Steel

The experiments were carried out to determine the transient behavior of the inclusion in Si-deoxidized stainless steel for high-grade plate. The samples were taken from three heats of the steel during the whole production process from the AOD to the mold, which were subsequently examined by an automatic scanning electron microscope with field energy dispersive spectrometer (FE-SEM&EDS). It can be summarized that appropriate calcium treatment intensity could modify inclusions into liquid ones. Excessive calcium treatment above ([Ca] = 25 ppm) will increase the melting point of the inclusions, which cannot keep in the liquid region at the solidification temperature. Therefore, the calcium addition in Si-deoxidized stainless steels should be controlled to a relatively lower value ([Ca] = 10 ppm). In addition, the content of aluminum in steel also has an important influence on the control of inclusion. When the content of aluminum ([Al] = 0.012%) is too high, the inclusions in steel are difficult to be controlled within the liquid phase. The chemical evolution of the inclusions in steel at high temperature and during solidification process were comprehensively calculated, considering all types of inclusions such as calcium oxide, aluminum oxide, silicon oxide, calcium aluminate, calcium silicate, mullite, and liquid inclusion. The thermodynamic calculations are in good agreement with experimental results, which can predict the formation of the inclusions in Si-deoxidized stainless steels.

Void Nucleation on a Contaminated Patch

1997 ◽  
Vol 12 (8) ◽  
pp. 2038-2042 ◽  
Author(s):  
B. M. Clemens ◽  
W. D. Nix ◽  
R. J. Gleixner
Keyword(s):  
Contact Angle ◽  
Simple Model ◽  
Integrated Circuit ◽  
Driving Force ◽  
Void Nucleation ◽  
Equilibrium Contact Angle ◽  
Simple Relationship ◽  
Nucleation Behavior ◽  
Strong Function ◽  
Nucleation Barrier

The energetics of a simple model of void nucleation on a contaminated patch between the sidewall and metal in an integrated circuit interconnect are examined to determine void nucleation behavior. The conditions under which there is no void nucleation barrier are represented by a simple relationship between the volume driving force, the equilibrium contact angle, the surface energy of the metal, and the contaminated patch radius. The void nucleation barrier, when it exists, is a strong function of these same parameters, and increases sharply as the driving force decreases, and under some conditions, increases with increasing equilibrium contact angle.

scholarly journals Yield and Disease Resistance of Six Tomato Cultivars Grown in Two Media and Three Calcium Concentrations

HortScience ◽  
1997 ◽  
Vol 32 (3) ◽  
pp. 470B-470
Author(s):  
Rebecca S. Boone ◽  
Carl E. Sams ◽  
William S. Conway
Keyword(s):  
Disease Resistance ◽  
Fruits And Vegetables ◽  
Calcium Content ◽  
Water Soluble ◽  
Pine Bark ◽  
Calcium Treatment ◽  
Marketable Yield ◽  
Tomato Production ◽  
Significant Difference ◽  
Tomato Cultivars

Calcium has been linked to disease resistance in fruits and vegetables. The effects of calcium nutrition on six hydroponically grown tomato cultivars (`Switch', `Match', `Blitz', `Caruso', `Trust', and `Celebrity') were evaluated in the fall of 1996. Disease resistance and yield were measured for plants grown in either perlite or pine bark mulch. Plants were fertilized with a 5N–11P–26K water-soluble fertilizer solution containing micronutrients and either 60, 120, or 185 mg·L–1 calcium. Disease resistance was determined by measuring disease lesion diameters on mature green harvested fruit 3 to 5 days after inoculating with Botrytis cinerea Pers.: Fr. There was no significant difference in disease when evaluated by medium, cultivar, or calcium treatment. Foliar analysis by Inductively Coupled Argon Plasma Atomic Emission Spectrophotometer (ICAP) indicated that leaf calcium content ranged from 27,000 to 54,000 μg·g–1 dry weight (leaf above fifth flower cluster), but was not significantly different when analyzed by medium, cultivar, or calcium treatment. There was no significant difference in marketable yield due to medium or calcium treatment. Among cultivars, `Trust' had the highest marketable yield at 2.7 kg per plant, which was significantly different from `Celebrity' at 1.6 kg per plant. This experiment suggests that a cheaper medium (pine bark) and lower calcium levels can be utilized in fall tomato production.

scholarly journals Postharvest Response of Two Strawberry Cultivars to Foliar Application of CaCl2

HortScience ◽  
1991 ◽  
Vol 26 (9) ◽  
pp. 1186-1188 ◽  
Author(s):  
F. Chéour ◽  
C. Willemot ◽  
J. Arul ◽  
J. Makhlouf ◽  
Y. Desjardins
Keyword(s):  
Organic Acids ◽  
Foliar Application ◽  
Calcium Content ◽  
Disease Development ◽  
Fruit Firmness ◽  
Fragaria Ananassa ◽  
Calcium Treatment ◽  
Free Sugars ◽  
Low Levels ◽  
Strawberry Cultivars

The objective of this study was to compare the effects of the foliar application of CaCl2 on the shelf life and Ca content of the fruit of the strawberry (Fragaria × ananassa) cultivars Kent and Glooscap, which differ in fruit firmness. Calcium was applied repeatedly, 3 days, 3 and 6 days, or 3, 6, and 9 days before harvest at 0, 10, or 20 kg·ha-1. Calcium treatment influenced amounts of free sugars and organic acids, color, texture, and disease development during storage in air at 4C. Calcium application had more effect on the fruit of the softer `Glooscap', which contained relatively low levels of Ca at the time of treatment. Calcium content of the fruit appeared to depend mainly on the ability of the plant to accumulate and distribute Ca.

Effect of slag-metal composite cored wire feeding on the cleanness of Al-containing steel

2019 ◽  
Vol 116 (2) ◽  
pp. 221
Author(s):  
Shuo Zhao ◽  
Yangyang Ge ◽  
Fuli Zhang ◽  
Jingcai Lyu ◽  
Tao Yan ◽  
...  
Keyword(s):  
Calcium Aluminate ◽  
Metal Composite ◽  
Calcium Treatment ◽  
Initial Composition ◽  
Secondary Oxidation ◽  
Cored Wire ◽  
Lower Melting Point ◽  
Wire Feeding ◽  
Core Powder ◽  
Inclusions In Steel

The metal yield is low in traditional calcium treatment processing and secondary oxidation of molten steel can be serious. As such, it is of great interest to control the inclusions in steels by feeding the CaO-Al2O3-Ca composite cored wire as an alternative treatment where calcium is protected from sublimation until in contact with the melt. To analyse the effect of composite cored wire on cleanliness of the liquid steel, the evolution of inclusions in steel has been investigated. The initial composition of the calcium aluminate in composite cored wire was changed systematically, and reacted with Al-containing steel to study the effects of starting composition. It can be concluded that when the content of calcium aluminate in the core powder is 80 wt-% to 90 wt-% (the yield is 10%) or the content is 90 wt-% (the yield is 20%), the typical inclusions which have a lower melting point in the steel are spherical CaO-MnO-SiO2-Al2O3, when the calcium aluminate content reaches to 70 wt-% (the yield is 10%) or the content reaches to 70 wt-% to 80 wt-% (the yield is 20%), CaO-MgO-Al2O3 or CaO-Al2O3 is more easily generated in the steel, Al2O3 is gradually reduced.

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