Steelmaking

Selecting secondary refining technology properly and pushing forward construction of high efficient and low cost“clean steel platform”

2010, 26(01): 1-6. doi:

Asbtract ( 679 )

Related Articles | Metrics

The iron and steel industry at home and abroad is now facing a very serious challenge of the worldwide financial crisis today. One of the key points for readjustment and rejuvenation of the iron and steel industry of China is to adjust and optimize the products and processes by means of scientific and technological progress and in the meanwhile acceleratedly pushing forward the construction of the high efficient and low cost “clean steel platform” has become one of the current scientific and technological innovative tasks of the iron and steel works. The development of secondary refining technology in China has already gone through three important phases, namely initial step, popularization and optimization and uptodate with a very clearcut guiding principle it has grown up to a certain level and scale and has accumulated experience and taken hold of quite a number of key technologies. However certain problems such as low refining ratio,incompetency of properly selection and application of the refining functions still need to be further improved.The high efficent and optimal technological processes of the secondary refining for such a few typical steel grades as the long products, hot rolled coils, medium plate and cold rolled sheets have to be studied and summarized in order to provide some referential experience for enterprises of the various kind. Deepening our understanding of the functions of different types of the secondary refining and properly selecting them will be propitous to the standardization of the basic secondary refining processes for different types of products as well as be beneficial to expedite the construction of the high efficient and low cost “clean steel platform”.

Research and application of dephosphorization in 250 t combined blowing converters

2010, 26(01): 7-12,5. doi:

Asbtract ( 630 )

Related Articles | Metrics

Based on the production practice in No.3 Branch of General Steel-making Plant of WISCO, this paper discusses the factors affecting dephosphorization, such as liquid bath heat balance control, slag basicity, slag quantity and slag oxidability etc. Furthermore, proceeding from the dynamic model parameters adjustment, optimization of the static mode calculatioon, control of [%C] [%O] and development of the slag splashing model and etc. this paper also researches on how to ensure the effect of the combined blow and reduce phosphorus content at the end point of steelmaking by automatic steelmaking on condition that the combined blowing effect can be ensured without increase of the oxygen content in liquid steel at the end point of steelmaking. By application of the above-mentioned technological measures in No.3 Plant of General Steel-making Plant of WISCO good results have been achieved.

Steelmaking practice on of ML35 cold-heading steel

2010, 26(01): 13-15,2. doi:

Asbtract ( 1636 )

Related Articles | Metrics

In light of the problems existing in the initial stage of refining the cold heading steel ML35 in the Kunming Iron and Steel Co., Ltd, WISCO (hereafter referred to as Kungang) such as low ratio of equiaxed .zone , apparent central cavity and central segregation , fluctuation in control of the AlS amount in steel and frequent nozzle blockings in tundish, the causes to the defects are analyzed and to solve those problems a series of technological measures accordingly adopted including optimization of the technical parameters of electromagnetic stirring in the mould, increase of the ratio of the central equiaxed zone of the slab, solution of the defects of the slab such as the central cavity and central segregation, stabilization of AlS in steel by 3 step control process, solution of the difficult problem of the frequent nozzle blockage in the tundish by proper selection of the Ca treatment and adoption of CC protective casting. As the results the consecutive casting heats for the tundish are increased and production of cold heading steel ML35 stabilized as well.

Study and industrial application of compound basic slag for tundish

2010, 26(01): 16-20. doi:

Asbtract ( 684 )

Related Articles | Metrics

In order to improve the steel cleanliness and reduce the accidents of nozzle clogging resulting from Al2O3 inclusion, research and development of the basic slag for the tundish has been carried out according to the theoretical knowledge of the metallurgical slag in connection with practical conditions of the continuous casting in the Steel-making Plant of Chongqing Steel. As the results a few difficult problems about the basic slag for the tundish encountered in the continuous casting are solved and the production is carrying on very smoothly and in the meanwhile very satisfactory metallurgical results are achieved as well.

Effect of deoxidation technology on control of oxide inclusions in the wheel steel

2010, 26(01): 21-24. doi:

Asbtract ( 629 )

Related Articles | Metrics

Effects of various deoxidation processes on the control of oxide inclusions in the wheel steel have been verified in terms of selection of the deoxidizing materials, time and mode of material charging as well as methods for removal of the deoxidation products. Results show that inclusions class B in steel can be very effectively reduced and the technological requirements of the wheel steel for inclusions class B in steel be fully satisfied by adoption of the processing route of pre-deoxidation prior to tapping—LF—Al addition one single time—Ca treatment.

Re-utilization of LF hot refining slag in converter steel-making plant

2010, 26(01): 25-27. doi:

Asbtract ( 1580 )

Related Articles | Metrics

The present article introduces the experiments on the re-utilization of LF hot refining slag in the Converter Steel-making Plant of Hangzhou Iron and Steel Group Co.. The result shows that the technology can ensure desulfurization purpose in refining motlen steel, and the Als content in the motlen steel is quite large. The hot metal yield by the new technology is 1.178t/heat higher than that by the original technology. The production cost reduces by 22.4028yuan per ton steel. At the same time extensive application of the technology show that the technology is capable of guaranting the quality of molten steel and reducing the cost in the actual production.

Research and control of mountain cracks on medium plate

2010, 26(01): 28-31,7. doi:

Asbtract ( 684 )

Related Articles | Metrics

The peak shaped cracks on the surfae of the medium plate is the primary cause to the substandard rate of the steel products. On the basis of systematic investigation and analysis it’s proved that the defect originates primarily from the transversal crack of the inner bow of the slab and the causes to the crack are closely related not only to the chemical compositions of the steel grade, but also to the conditions of the protective casting and performance of the equipments. The transversal cracks of the slab can be reduced effectively by optimization of the composition design, improvement in the effect of the protective casting and guarantee of the control accuracy of the key equipments of the continuous caster such as mould, vibration table and segments.

Analysis of nitrogen content in refining the bearing steel GCr15 byUHP-EAF→LF(VD) → CC process

2010, 26(01): 32-35. doi:

Asbtract ( 741 )

Related Articles | Metrics

The present paper analyzes the changes of the nitrogen content in GCr15 bearing steel and its influential factors in refining this steel grade in Nanjing Iron and Steel United Co Ltd by the processing route of UHP-EAF→LF(VD) →CC, namely a 100 t high impedance UHP-EAF, a 100t ladle refining furnace, billet continuous caster with the cross-section of 150 mm×150 mm. Production practice shows that in order to reduce the nitrogen content in the bearing steel over 55% not metal has to be charged into the EAF and foaming slag operation be adopted and as the results he average nitrogen content in steel comes up to 29×10-6 at arc furnace tapping period. By implementaion of large quantity slag and embedding arc operation and Argon stirring in the process of LF refining the increment of average nitrogen content is 21.8×10-6 and the decrease of nitrogen content in the process of VD vacuum Argon blowing is 15×10-6 and in whole process of gas-shielding casting the increment of average nitrogen content is 6.3×10-6. Since the increment of average nitrogen content during the LF refining is critical to the whole process the LF refining process should be optimized in the period.

Technological research on refining high quality bloom of seamless tube with medium phosphor hot metal by“single type slag method”

2010, 26(01): 36-39,5. doi:

Asbtract ( 1410 )

Related Articles | Metrics

The present paper introduces the converter refining method, in which high quality steel grade can be produced by implementation of “the single type slag process” with medium phosphor hot metal under the conditions of absence of the advanced secondary refining equipments and absence of hot metal pretreatment of dephoshorization, namely “ High tapping carbon and deep dephosphorization method.” The study involves such a few technologies as the oxygen supply, blowing, slagging, end-point control and deoxidation alloying. Throughout more than two years of industrial application very satisfactory results have been achieved and enormous economic and social efficiencies obtained as well.

Experimental study on increase of end-point manganese byaddition of manganese ore in converter

2010, 26(01): 40-43. doi:

Asbtract ( 759 )

Related Articles | Metrics

The present paper introduces the mechanism of manganese ore reduction and experimental study and even actual effects of increase in the end point manganese content in steel by adding manganese ore during converter steelmaking process. Factors influencing residual manganese at blow end point in steel are analyzed. Some techniques and measures for increasing rsidual manganese at blow end point in steel by adding manganese ore during converter steelmaking process are put forward.

Calculation of alloy addition of BOF steelmaking based onpredicting yield model

2010, 26(01): 44-47. doi:

Asbtract ( 2364 )

Related Articles | Metrics

In the process of BOF steelmaking in order to figure out the reasonable amount of alloy addition during deoxidizing and alloying of tapping, the predicting model for alloying yield of tapping is developed based on the knowledge of alloying yield, using support vector machine; and the alloy addition with the yield figured out by the model is calculated. In the study simulation is carried out with the practical prodution data. Results shows that the alloy addition calculating model of BOF based on predicting yield is up to the mustard of practical manufacturing.

Research on effect of nozzle on secondary cooling results in Slab continuous casting process

2010, 26(01): 48-52. doi:

Asbtract ( 738 )

Related Articles | Metrics

The secondary cooling of slab continuous casting is one of the important factors affecting the quality of slab. In this paper, for the purpose of solving the problem of slab quality defects and improving slab quality in No.3 Steelmaking Plant of Handan Iron and Steel Group Co.Ltd, the nozzles of secondary cooling system are optimized. The proper types of nozzles are determined and main factors influencing the nozzle's performance analyzed. On the basis of the previous research, by means of optimization of nozzle type, pattern of nozzle arrangement and cooling water volume the central segregation of slabs has been improved and the equiaxed crystal ratio prominently raised.

Study on parameters for slab dynamic soft reduction system

2010, 26(01): 53-57. doi:

Asbtract ( 717 )

Related Articles | Metrics

The Dynamic soft reduction system of stainless steel slab continuous casting machine in Taishan Steel including the segments, control system and calculation module are all domestic designed and manufactured and thus the aim of whole dynamic soft reduction system made in China is realized for the first time. Practice shows that the casting machine is featured of high stability, calculation of the module is accurate and the quality of the slab is excellent. In the process of soft reduction the deformation of the segments is effectively compensated. The critical control parameters for the dynamic soft reduction technology are optimized through a series of production experiments and the optimal parameters for soft reduction determined.

Technological revamp on SN mechanism and related systems ofslide gate of 250t ladle

2010, 26(01): 58-61. doi:

Asbtract ( 692 )

Related Articles | Metrics

The prewent paper introduces the adaptability technology adopted in the revamp of the slide gate mechanism and related systems of the250t ladle in Baosteel and analyzes the economic efficiencies achieved in the revamp project on the basis of the numerous data. The experiments achieved in the revamp project can be used as an useful referrence for the revamp of the slide gate mechanism of the large ladle.

Research on slab broadening and mould setting

2010, 26(01): 62-65. doi:

Asbtract ( 1328 )

Related Articles | Metrics

The relation between slab broadening and mould size setting is studied on the basis of the actual production in several continuous casting manufactures. By comparison of the results of investigation in the mould setting data of 5 coninuous casting plants with the design handbook of the continuous caster it’s found out that the broadening phenomenon of slab exists extensively in the continuous casting process in the five continuous casting plants; and the change of the slab width is the outcome of compensation of broadening of a slab with its shrinkage in the period from initial occurrence of shell to the formation of the solidified strand; and the apparent shrinkage ratio of a slab is the difference between the linear shrinkage and the ultimate broadening of the slab; and the ratio of ultimate broadening of slab for the five investigated plants ranges from 0.34% to 2.03% and the ratio of apparent shrinkage from 0.47% to 2.16%.

Practice on the revamp of secondary cooling zone ofheavy round bloom continuous caster

2010, 26(01): 66-69. doi:

Asbtract ( 631 )

Related Articles | Metrics

In light of the problems of low equiaxed crystal ratio and serious carbon segregation existing in the secondary cooling zone (full water cooling) of the heavy round bloom continuous caster in Ma’anshan Iron and Steel Co.,Ltd. In the process of developing high quality wheel steel technical revamp on the secondary zone of the continuous caster mainly involving adoption of spray cooling has been carried out and as the results temperature distribution on the surface of the slab is more homogeneuos, the texture of the slab turns to be denser, the equiaxed crystal ratio rises by 8% and the the carbon segregation index cuts down by 0.03.

Technology of foaming slag level control during latter period of blowing for BOF process

2010, 26(01): 70-73. doi:

Asbtract ( 833 )

Related Articles | Metrics

The technologies to control the level of foaming slag during the latter period of blowing for BOF process inome steelmaking works were introduced. The temperature difference method, microwave method and acoustical method are used for measuring the level of foaming slag during the blowing. By usage of the technologies not only the slopping frequency cab be reduced, but the nitrogen content in steel also decreased at the end point of blowing. Moreover, the feasibility of temperature difference method used for the converter of Shougang Qian’an Iron & Steel Co., Ltd is discussed.

Status quo of research on MgAl2O4 spinel inclusion in steel and trend of its development

2010, 26(01): 74-78. doi:

Asbtract ( 833 )

Related Articles | Metrics

The non-metallic spinel inclusion, MgAl2O4, is an undeformed inclusion in steel with high melting point .Therefore it is very harmful in the production of high grade steels. In the recent years research on the MgAl2O4 inclusion in steels has become a hot spot and received more and more attention in the sector of clean steel research. In the current paper the background of occurrence of MgAl2O4 inclusion in steels are introduced and researches on MgAl2O4 inclusion in steels reviewed and then further study on the kinetics of transformation of liquid melting compound inclusions from MgAl2O4 is proposed.

Table of Content