Investigation of Optimal Continuous Casting Condition for Superior Steel Cleanliness

Author(s):  
S. Chen ◽  
B. Konar ◽  
J. Saroop
Metals ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 852 ◽  
Author(s):  
Branislav Bul’ko ◽  
Marek Molnár ◽  
Peter Demeter ◽  
Dana Baricová ◽  
Alena Pribulová ◽  
...  

Modern steel plants produce today a large portfolio of various steel grades, many for end-uses demanding high quality. In order to utilize the maximum productivity of the continuous-casting machine, it is sometimes necessary to cast steel grades with different chemical compositions in one sequence. It is important, therefore, to know the possibilities of a specific continuous-casting machine to make the Intermix connections as short as possible. Any interference with established procedures may, however, have a negative impact on the cleanliness of the cast steel. Using physical and numerical simulation tools, it was found that reducing the steel level in the tundish during the exchange of ladles makes it possible to shorten the transition zone. However, when the steel level is reduced, the flow of steel is impaired, which can have a negative effect on the cleanliness of the cast steel and, in extreme cases, may even lead to entrapment of slag in the mold. The cleanliness of cast steel was evaluated using one of the most advanced tools for automatic steel cleanliness evaluation, AZtecFeature (Oxford Instruments, Abingdon, UK), which enables determination of the type, size, distribution, and shape, as well as the chemical composition, of individual types of non-metal inclusions.


2011 ◽  
Vol 194-196 ◽  
pp. 150-156 ◽  
Author(s):  
Fang Dong ◽  
Cheng Su ◽  
Yuan Yuan Bai

Hot-ductility tests of the microalloyed Q345B structural steel were performed in a tensile machine of Gleeble-1500D at different strain rates of 1.5•10-3/s 、2.5•10-3/s and 2•10-2/s and at temperature range from 1300°C to 700°C(Δ T=100°C ), which are close to the continuous casting condition of steel. Fracture surfaces were examined using a scanning electron microscope; it was found that the hot decrease as strain rate decrease, because the void growth mechanism predominates over void nucleation, giving time for nucleation cracks to grow. The minimum ductility was found at about 800°C for the strain rates of 1.5•10-3/s and 2.5•10-3/s, and the fracture was intergranular. The steel has good plasticity in temperature range from 1200°C to 900°C which is suitable for straighten operation.


2007 ◽  
Vol 38 (1) ◽  
pp. 63-83 ◽  
Author(s):  
LIFENG ZHANG ◽  
SUBO YANG ◽  
KAIKE CAI ◽  
JIYING LI ◽  
XIAOGUANG WAN ◽  
...  

2013 ◽  
Vol 44 (5) ◽  
pp. 1185-1189 ◽  
Author(s):  
P. Palai ◽  
P. P. Sahoo ◽  
Arghya Dey ◽  
T. K. Roy ◽  
V. V. Mahashabde

2009 ◽  
Vol 106 (6) ◽  
pp. 242-247
Author(s):  
C. Damerval ◽  
H. Tavernier ◽  
L. Avedian ◽  
P. Disant ◽  
P. Delfosse ◽  
...  

2020 ◽  
Vol 117 (6) ◽  
pp. 619
Author(s):  
Rui Xu ◽  
Haitao Ling ◽  
Haijun Wang ◽  
Lizhong Chang ◽  
Shengtao Qiu

The transient multiphase flow behavior in a single-strand tundish during ladle change was studied using physical modeling. The water and silicon oil were employed to simulate the liquid steel and slag. The effect of the turbulence inhibitor on the slag entrainment and the steel exposure during ladle change were evaluated and discussed. The effect of the slag carry-over on the water-oil-air flow was also analyzed. For the original tundish, the top oil phase in the impact zone was continuously dragged into the tundish bath and opened during ladle change, forming an emulsification phenomenon. By decreasing the liquid velocities in the upper part of the impact zone, the turbulence inhibitor decreased considerably the amount of entrained slag and the steel exposure during ladle change, thereby eliminating the emulsification phenomenon. Furthermore, the use of the TI-2 effectively lowered the effect of the slag carry-over on the steel cleanliness by controlling the movement of slag droplets. The results from industrial trials indicated that the application of the TI-2 reduced considerably the number of linear inclusions caused by ladle change in hot-rolled strip coils.


Author(s):  
A. T. Kunakbaeva ◽  
A. M. Stolyarov ◽  
M. V. Potapova

Free-cutting steel gains specific working properties thanks to the high content of sulfur and phosphorus. These elements, especially sulfur, have a rather high tendency to segregation. Therefore, segregation defects in free-cutting steel continuously cast billets can be significantly developed. The aim of the work was to study the influence of the chemical composition of freecutting steel and casting technological parameters on the quality of the macrostructure of continuously cast billets. A metallographic assessment of the internal structure of cast metal made of free-cutting steel and data processing by application of correlation and regression analysis were the research methods. The array of production data of 43 heats of free-cutting steel of grade A12 was studied. Steel casting on a five-strand radial type continuous casting machine was carried out by various methods of metal pouring from tundish into the molds. Metal of 19 heats was poured with an open stream, and 24 heats – by a closed stream through submerged nozzles with a vertical hole. High-quality billets had a cross-sectional size of 150×150 mm. The macrostructure of high-quality square billets made of free-cutting steel of A12 grade is characterized by the presence of central porosity, axial segregation and peripheral point contamination, the degree of development of which was in the range from 1.5 to 2.0 points, segregation cracks and strips – about 1.0 points. In the course of casting with an open stream, almost all of these defects are more developed comparing with the casting by a closed stream. As a result of correlation and regression analysis, linear dependences of the development degree of segregation cracks and strips both axial and angular on the sulfur content in steel and on the ratio of manganese content to sulfur content were established. The degree of these defects development increases with growing of sulfur content in steel of A12 grade. These defects had especially strong development when sulfur content in steel was of more than 0.10%. To improve the quality of cast metal, it is necessary to have the ratio of the manganese content to the sulfur content in the metal more than eight.


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