The Effect of Temperature Fluctuation on the Formation of Billet Surface Defect in the Initial Solidification Area

2010 ◽  
Vol 148-149 ◽  
pp. 163-167
Author(s):  
Xiao Li Jin ◽  
Zuo Sheng Lei ◽  
Kang Deng ◽  
Zhong Ming Ren
Keyword(s):  
Continuous Casting ◽  
Temperature Fluctuation ◽  
Surface Defects ◽  
Casting Process ◽  
Effect Of Temperature ◽  
Billet Surface ◽  
Maximum Value ◽  
Key Factor ◽  
Oscillation Marks ◽  
Initial Solidification

The heat transfer in steel continuous casting process under mold oscillation was calculated, and temperature fluctuation phenomena was found in the initial solidification area, the maximum value was approximate 16 °C. The effect of different continuous casting parameters on temperature fluctuation were analyzed, and the temperature fluctuation was considered to be a key factor to the formation of oscillation marks. The Index of Temperature Fluctuation(ITF) was proposed to predict the effect of temperature fluctuation on the formation of billet surface defects.

Continuous Casting of Microalloyed Steels. Influence of Composition and Operational Parameters in Billet Surface Cracking

2005 ◽  
Vol 500-501 ◽  
pp. 163-170 ◽  
Author(s):  
G. Alvarez de Toledo ◽  
A. Arteaga ◽  
J.J. Laraudogoitia
Keyword(s):  
Continuous Casting ◽  
Surface Defects ◽  
Casting Process ◽  
Precipitate Size ◽  
Microalloyed Steels ◽  
Cast Billet ◽  
Main Concern ◽  
Operational Parameters ◽  
Solidification Model ◽  
Billet Surface

Surface defects, mainly intergranular cracks (IGC), in as cast billet is the main concern for the production of microalloyed steels with the continuous casting process. A description is given of the IGC in the as cast billet surface and the main casting parameters influencing its formation. An analytical model of the influence of the microalloyed content in the formation of precipitates and the corresponding billet surface ductility at the temperature of billet straightening is presented. The model was validated with bibliographical ductility experimental values and was used to perform composition optimisation for continuous casting production. The analytical approach has been completed with a numerical precipitation model coupled with a continuous casting billet solidification model. The coupled program allows precipitate size distribution calculation in selected points of the cross billet section as a function of production parameters, steel composition and billet size. These precipitate distributions are important to detect ductility problems in billets and to optimise the operational parameters so as to avoid these problems.

scholarly journals Investigation and Minimization of Slag Spot Surface Defects in Continuous Casting of High Carbon Steel Billets through Statistical Evaluation

Metals ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 878
Author(s):  
Yong-feng Chen ◽  
Li Zhao ◽  
Xiao-tan Zuo ◽  
Qun-nan Tao ◽  
Hong-biao Zhang ◽  
...  
Keyword(s):  
Carbon Steel ◽  
Continuous Casting ◽  
Molten Steel ◽  
Surface Defects ◽  
High Carbon Steel ◽  
Inlet Temperature ◽  
External Diameter ◽  
Mold Powder ◽  
High Carbon ◽  
Billet Surface

Slag spot surface defects often appear during continuous casting of high carbon steel billets due to the solidification characteristics of molten steel in the mold. To target the problem of surface slag spot defects that occur frequently during the continuous casting of high-carbon steel strands, we analyzed the influence of molten steel superheat, accumulated service time and the water inlet temperature of the mold, the size of the submerged entry nozzle and the physical and chemical properties of the mold powder on the slag spot defects. The production practice shows that by adjusting the superheat of molten steel to 30–35 °C, the water inlet temperature of the mold is stable at 33–35 °C. To adjust the internal and external diameter of the immersion nozzle to 30–70 mm, the viscosity and melting temperature of the mold powder were adjusted from 0.45–0.55 Pa·s, 1100–1140 °C to 0.15–0.25 Pa·s, 1020–1060 °C. The final billet surface quality was improved significantly, the billet surface was smooth, the oscillation marks were relatively smooth and regular and the slag trench ratio was reduced from the original maximum of 40–50% to less than 1%.

scholarly journals Formation of Surface Depression during Continuous Casting of High-Al TRIP Steel

Metals ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 204 ◽  
Author(s):  
Heng Cui ◽  
Kaitian Zhang ◽  
Zheng Wang ◽  
Bin Chen ◽  
Baisong Liu ◽  
...  
Keyword(s):  
Continuous Casting ◽  
Trip Steel ◽  
Mold Flux ◽  
Casting Process ◽  
Peritectic Steel ◽  
Al Content ◽  
Steel Slab ◽  
Oscillation Marks ◽  
High Al Content ◽  
Surface Depression

High aluminum transformation-induced plasticity (TRIP) steels offer a unique combination of high tensile strength and ductility, high impact energy absorption and good formability. The surface of the slab is prone to depressions and longitudinal cracks during continuous casting due to the high Al content in steels. Surface depressions of the 1.35 wt.% Al-TRIP steel slab in a steel works were investigated by scanning electronic microscopy (SEM) and mold fluxes with different Al2O3/SiO2 ratios were researched by thermodynamic calculations and high-temperature static balance experiments. The results show that some micro-cracks were distributed along the grain boundary in the surface depression of the slab. Inclusions containing K and Na, which were probably from mold flux, were found in the depression samples. Meanwhile, the components of reactive mold flux showed significant variation in their chemical composition during the continuous casting process of the Al-TRIP steel. A large number of depressions and irregular oscillation marks on the Al-TRIP steel slab surface were generated due to serious deterioration in the physical properties of the mold flux. Since the TRIP steel is a typical hypo-peritectic steel, the overly large thermal contraction and volume contraction during initial solidification is the intrinsic cause of surface depression. The change of mold flux properties during casting aggravates the formation of depressions.

scholarly journals Effect of High Temperature Deformation on the Hot Ductility of Nb Microalloyed Steel

2005 ◽  
Vol 500-501 ◽  
pp. 115-122 ◽  
Author(s):  
Faramarz Zarandi ◽  
Steve Yue
Keyword(s):  
Continuous Casting ◽  
High Temperatures ◽  
Microalloyed Steel ◽  
Casting Process ◽  
Temperature Deformation ◽  
Hot Ductility ◽  
Continuous Casting Process ◽  
Billet Surface ◽  
Nb Microalloyed Steel ◽  
Very High

Low hot ductility of steel at the straightening stage of the continuous casting process is a problem found in steels containing microalloying and/or certain alloying additions. The thermal schedule undergone by the billet surface in the mill has a significant effect on the hot ductility. In this work, thermomechanical processing was employed to alleviate the problem of hot ductility in the Nb-microalloyed steel. Specimens were melted in situ and subjected to the billet surface thermal schedule in order to generate a microstructure similar to that present at the straightening stage of the continuous casting process. Some deformation schedules were incorporated with the thermal schedule at very high temperatures, specifically during solidification, within the d-ferrite region, and during the d®g transformation, and the hot ductility was subsequently evaluated at the end of the thermal schedule where the straightening operation is performed. After the thermal schedule alone, the steel exhibited a very low hot ductility at the straightening stage. It was found that deformation at very high temperatures prior to the straightening stage had a considerable effect on the hot ductility, either detrimental or beneficial, depending on the region in which the deformation has been executed. The mechanisms leading to loss and improvement of hot ductility are explained in this paper.

Effect of Water Gap in Delivery System on Twin Roll Strip Caster by Simulation

2014 ◽  
Vol 602-603 ◽  
pp. 652-655
Author(s):  
Luo Cheng Yang ◽  
Hong Xi Zhu ◽  
Cheng Ji Deng ◽  
Wen Jie Yuan ◽  
Jun Ding
Keyword(s):  
Continuous Casting ◽  
Delivery System ◽  
Surface Defects ◽  
Continuous Caster ◽  
Casting Process ◽  
Finite Element Software ◽  
Actual Production ◽  
Quality Material ◽  
Comsol Simulation ◽  
Twin Roll

In continuous casting process, the mould is the core of the continuous caster, and the vast majority of the surface defects of steel is originated in the crystallizer. Choosing a reasonable water gap in the delivery system is particularly important, especially in twin roll strip continuous casting, the flow delivery system thin belt has a close relationship with the quality of the products. Experiments to skateboard and water gap, STEEL AISI 4340 materials chosen as the simulation material at the same time, distribution water gap taking the form of a set themselves by using the finite element software COMSOL simulation calculation of different gaps opening mode of velocity field, and fluid line back to the high wall, made a comprehensive analysis in different speak way open comprehensive effect is best, the most conducive to the production of high quality material. The experiment determines the best form of water gap, improving the efficiency of the actual production. Make it to the actual production has a certain guiding significance.

scholarly journals Monitoring Surface Defects Deformations and Displacements in Hot Steel Using Magnetic Induction Tomography

Sensors ◽  
2019 ◽  
Vol 19 (13) ◽  
pp. 3005 ◽  
Author(s):  
Fang Li ◽  
Stefano Spagnul ◽  
Victor Odedo ◽  
Manuchehr Soleimani
Keyword(s):  
Continuous Casting ◽  
Magnetic Induction ◽  
Surface Defects ◽  
Surface Deformation ◽  
Real Life ◽  
Steel Production ◽  
Casting Process ◽  
Contactless Method ◽  
Image Region ◽  
Magnetic Induction Tomography

Magnetic Induction Tomography (MIT) is a non-invasive imaging technique that has been widely applied for imaging materials with high electrical conductivity contrasts. Steel production is among an increasing number of applications that require a contactless method for monitoring the casting process due to the high temperature of hot steel. In this paper, an MIT technique is proposed for detecting defects and deformations in the external surfaces of metal, which has the potential to be used to monitor the external surface of hot steel during the continuous casting process. The Total Variation (TV) reconstruction algorithm was developed to image the conductivity distributions. Nonetheless, the reconstructed image of the deformed square metal obtained using the TV algorithm directly does not yield resonable images of the surface deformation. However, differential images obtained by subtracting the image of a perfect square metal with no deformations from the image obtained for a deformed square metal does provide accurate and repeatable deformation information. It is possible to obtain a more precise image of surface deformation by thresholding the differential image. This TV-based threshold-differencing method has been analysed and verified from both simulation and experimental tests. The simulation results reported that 0.92 % of the image region can be detected, and the experimental results indicated a 0.57 % detectability. Use of the proposed method was demonstareted in a MIT device which was used in continuous casting set up. The paper shows results from computer simulation, lab based cold tests, and real life data from continoeus cating demonstating the effectiveness of the proposed method.

scholarly journals Reducing Surface Cracks and Improving Cleanliness of H-Beam Blanks in Continuous Casting — Improving continuous casting of H-beam blanks

2019 ◽  
Vol 38 (2019) ◽  
pp. 612-620
Author(s):  
Wei Chen ◽  
Gaiyan Yang ◽  
Liguang Zhu ◽  
Xingjuan Wang ◽  
Baomin He
Keyword(s):  
Continuous Casting ◽  
Process Parameters ◽  
Casting Process ◽  
Temperature Fields ◽  
Control Surface ◽  
Surface Cracks ◽  
Key Factors ◽  
Key Factor ◽  
Online Implementation ◽  
H Beam

AbstractA beam blank is ideal for H-beam production, but there are more defects in/on beam blanks than other common blanks. The study of the H-beam blank quality assurance system has great significance for production to determine the key factors causing defects and optimise the casting process parameters. Experimental analysis and numerical simulation, based on an actual production process, were used as research methods. The former was used to test and analyse the cracks, inclusions, and the flux in the mould to determine the preliminary factors causing defects in a beam blank. The latter was used to simulate the flow and temperature fields and the movement of inclusions to determine the key factor leading to defects and to optimize the casting process parameters. Online implementation of the recommendations of this project was developed, which proved that it is very useful and efficient to control surface cracks on the web and enhance cleanliness of an H-beam blank.

The Air Reoxidation and the Formation of Large Inclusions in Continuous Casting Process

1973 ◽  
Vol 59 (1) ◽  
pp. 72-84 ◽  
Author(s):  
Kichinosuke MATSUNAGA ◽  
Chikakazu NAMIKI ◽  
Taiji ARAKI
Keyword(s):  
Continuous Casting ◽  
Casting Process ◽  
Continuous Casting Process
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