Steelmaking

Trial on production ofGCr15 steel by converter-rectangular bloom caster route

2009, 25(01): 1-3,37. doi:

Asbtract ( 592 )

Related Articles | Metrics

The steel grade GCr15 has been produced by converter→secondary refining (LF+RH) →rectangular bloom caster process in Bengang Steel-making Works. All the chemical elements of GCr15 steel have reached the standard prescribed by Bengang and its harmful elements such as [Ti]=25×10-6,[Ca]=2×10-6,[O]=8×10-6,[N]=38×10-6,[H]=0.8×10-6 , preceded the demand of GB/T18254-2002 standard, and even reached the demand of Sweden SKF standard(SKF D33).

Study and application of calcium treatment for cold heading steel

2009, 25(01): 4-7,46. doi:

Asbtract ( 639 )

Related Articles | Metrics

The present paper describes the appropriate process parameters the No. 1 Steel-making Plant of WISCO finds out in the process of calcium treatment with Ca-Fe clad wire through a series of metallurgical experiments on Ca treatment in the laboratory . Very consistent Ca yield has been achieved and the problem of nozzle clogging in the process of continuous casting in refining the low silicon(≤0.04%) cold heading steel basically solved since application of the optimized Ca-treatment process parameters in the practical production.

Exploitation and trial-manufacture of DH36high strength hull plate in Tiangang

2009, 25(01): 8-10,1. doi:

Asbtract ( 627 )

Related Articles | Metrics

This paper makes a brief introduction to the practice on exploitation and trial-manufacture of DH36 high strength hull plate in Tianjin Iron and Steel Co., Ltd. The DH36 high strength hull plate has been manufactured by means of proper design on chemical compositions and strict control of the steelmaking and rolling processes, and as the results the certification of CCS has been successfully passed

Smelting Technology of High Purity Iron for Secondary Hardening Steel

2009, 25(01): 11-13. doi:

Asbtract ( 1278 )

Related Articles | Metrics

The smelting technology of high purity iron used for secondary hardening steels is introduced in this paper. The controlling methods during the smelting process of the high purity iron, with ultra-low phosphorus, low sulphur, low silicon, low manganese, low aluminum and low titanium, are also represented.

Production practice on casting the round tube blank of steel 20 with round tube blank continuous caster

2009, 25(01): 14-16. doi:

Asbtract ( 657 )

Related Articles | Metrics

The technical problems such as internal crack of round tube blank, tundish nozzle clogging and mould breakout have been solved in the continuous casting production of steel20，and high quality round tube blanks successfully produced with continuous caster by improvement and optimization of the refining and casting processes for steel 20。

Process practice for production of ultra-low carbon steel by RH-MFB route

2009, 25(01): 17-20. doi:

Asbtract ( 747 )

Related Articles | Metrics

The RH decarburization theory has been analyzed on the basis of RH decarburization static model. The overall results indicate that the practical decarburization level in Liangang´s RH needs to be further improved. Analysis on the main factors influencing the RH decarburization rate indicates that in order to obtain the optimal decarburization result it’s imperative to eliminate the pressure drop platform and maintain the whole processing vacuum degree below 400 Pa for more than 16min in the process of RH treatment and moreover, flow rate of argon should be controlled at 80~100Nm3/h in first 3~4 minutes after molten steel circulation starts and as soon as the vacuum degree reaches 8kPa (around 3 minutes),which is supposed to be the best juncture for blowing oxygen the height of oxygen lance should be maintained at 250-400cm and the oxygen flow rate be controlled at 1 200-1 600 m3/h. Practical results show that by application of these optimized measures the carbon content in liquid steel after treatment is steadily reduced to below 0.003%.

study and production practice of Q345E steel for driven well floor structure

2009, 25(01): 21-23,2. doi:

Asbtract ( 638 )

Related Articles | Metrics

Improvement in hit rate of chemical compositions by systematically controllingthe steel-making process

2009, 25(01): 24-27. doi:

Asbtract ( 1312 )

Related Articles | Metrics

The reasons for low hit rate of chemical compositions are investigated systematically. In order to raise the hit rate of the chemical compositions of the hot metal and ensure smooth production of thin slab continuous casting the system control technology as well as a series of advanced technologies have been applied in the hot metal pretreatment, converter refining and LF process. Results show that prominent efficiencies such as quality improvement, consumption reduction and productivity increase have already been achieved.

Study and practice on optimization of the flow control device of continuous casting tundish

2009, 25(01): 28-32. doi:

Asbtract ( 1487 )

Related Articles | Metrics

The flow field behavior of tundish with multi-hole dam in the No.7 billet caster of KISC is researched by hydraulic simulation experiment. Results show that the flow characteristics of every flow in tundish tend to be similar, the initial response time and average residence time of fluid increase, the volume of dead zone decreases and the metallurgical effect of tundish is improved obviously by setting up the multi-hole dam. The design plan of the No.3 multi-hole dam is assumed to be the preferred one. Since application of the experimental results into production the quality of billet has been improved clearly and the non-metallic inclusions of TS800U billet decreased from 52% to 3.5%.

A new algorithm of endpoint carbon content of BOF based on of off-gas analysis

2009, 25(01): 33-37. doi:

Asbtract ( 643 )

Related Articles | Metrics

Various algorithms of controlling the endpoint carbon content of BOF were studied on the basis of off-gas analysis. A new algorithm was suggested by analyzing the advantages and disadvantages of exponential decay models provided by Meyer H. W. and Uemura T. The principle of this algorithm is to standardize decarburization oxygen efficiency divided by the maximum decarburization oxygen efficiency of this heat, take advantage of the information of the reference decarburization curve, and carry out the multipoint calibration for the bath carbon content of this heat. The off-line simulation results for low carbon steel show that this algorithm has good suitability and will play an importance role in improving the control accuracy and hitting rate of the endpoint carbon content in BOF steelmaking practice.

Sub-lance control-based predication model for BOF end-point

2009, 25(01): 38-40. doi:

Asbtract ( 610 )

Related Articles | Metrics

The predication models on the end-point carbon content, temperature, phosphorus content and manganese content have been built up respectively by the decarburization index equation, the thermal equilibrium and the thermo-dynamical equation at the end-point of the converter oxygen blow process. When the error of end-point carbon content is ±0.015%, the predicting accuracy of the decarburization model arrives at above 87.6%; when the end-point carbon content of BOF is 0.03% the rate of the error of end-point temperature below 10℃ is 85.4%; When the error of end-point carbon and temperature is Δw(Mn)＝±0.02% and Δw(P)＝±0.003%, the predicting accuracies of the decarburization model are 87.0% and 81.2% respectively. The highly precise predication model has realized the simultaneous predication on the end-point carbon content , temperature , w(Mn ) and w(P ), and it provides a good foundation for improving the hit rate of end-point control of the BOF, reducing the number of reblow and carrying out direct tapping.

Study on the characteristics of critical gas flowrate forthe entrapment of slag in gas-stirred ladles

2009, 25(01): 41-46. doi:

Asbtract ( 663 )

Related Articles | Metrics

Analogies of water to hot metal and oil to liquid slag have been performed in a water model to investigate the critical gas flow rate for the slag entrapment in a bottom blow ladle. The results indicate that the critical gas flow rate for the slag entrapment decreases with increase of the oil depth and increase with increase of the oil viscosity. The validity and accuracy of use of the critical flow rate as the criterion of slag entrapment have been verified. By the way of analyzing the velocity distribution and energy balance in the metal-slag interface the dimensionless expression is derived as , which has be applied to calculation of the critical flow rate for slag entrapment in an actual gas stirred working ladle. On the basis of influencing factor analysis it is suggested that the gas flow rate should be held at less than 240L/min during inclusion removal operations in 110t ladle.

Optimization of the secondary cooling system in a round billet continuous caster

2009, 25(01): 47-50. doi:

Asbtract ( 681 )

Related Articles | Metrics

Internal crack has become a main quality problem in round billet which reduces the economical benefits greatly. This paper describes an investigation on the formation mechanism of internal crack in a round billet using measurement and numerical simulation to model the solidification process by building a thermo-mechanical coupling model. This FEM model has been validated by comparing the results including the surface temperature and the solidified shell thickness of round billet with experiment data. The strain and stress during the solidification process are also discussed. The reason of the internal crack is that the strain at the front edge of solidification exceeds the critical strain. Optimum process parameters of the secondary cooling system are also suggested by analyzing the influences of these parameters on the solidification process.

Study on the effect of dynamic soft reduction on the centerline segregation of continuously casting pipeline steel slab

2009, 25(01): 51-54. doi:

Asbtract ( 708 )

Related Articles | Metrics

This paper introduces the effect of different position of dynamic soft reduction on the inner quality of continuously casting slab. By etching the testing sample of the slab and checking and examining the dendrites over the cross section of the slab sample as well as analyzing the chemical compositions of the sample along the gauge direction it’s found out that the effect of dynamic soft reduction on the improvement in the central line segregation of the slab is extremely prominent. Results of the dendrite examination show that the central line segregation grades of all five testing samples of the slab for X70 pipeline steel are below BO.5 and both the internal crack grade and crack grade over the triangular zone are less than 0.5. Although the positions of the dynamic soft reduction for the five testing slabs are different, yet the internal quality of all the slabs are excellent and they are all in conformity with the inner control standards. In the meanwhile by calculating the segregation ratio of the elements along the gauge direction according to the analysis of the chemical compositions of the sample it’s found that the more desirable position of the dynamic soft reduction for the pipe line slab should be 。

A slab surface temperature prediction moder base on least square support vector machine

2009, 25(01): 55-59. doi:

Asbtract ( 662 )

Related Articles | Metrics

Effect of Ce on mechanical properties of 5CrNiMo die steel

2009, 25(01): 60-62. doi:

Asbtract ( 1303 )

Related Articles | Metrics

The alteration of the strength, plasticity and elastic ratio of 5CrNiMo die steel with four different additions of RE Ce is studied. The low cyclic fatigue life of 5CrNiMo die steel is calculated by studies on the changes of strength, plasticity and elasticity modulus after addition of different amount of the rare earth Ce into the die steel 5CrNiMo.The results show that strength and plasticity are improved greatly if the amount of addition of RE Ce is proper. And when the addition of RE Ce is controlled within the limit of 0.20% the strength and plasticity of the 5CrNiMo steel are maximized. Compared with the 5CrNiMo steel without RE Ce under the same rapture recurrent number the scope of the overall strain rises by 61.2%.

Operating practice of the tapping hole construction of300 t converter in Baosteel

2009, 25(01): 63-65. doi:

Asbtract ( 622 )

Related Articles | Metrics

The tapping hole is the important part of a converter. The repairing cycle of its inner lining is closely related with an enterprise's economic efficiency. This article elaborates the factors affecting the campaign life of the tapping hole of a converter. By improvement in the refractory materials as well as the working process of the tapping hole not only the overall campaign life of the inner lining of the tapping hole is extended, but also the production cost is reduced and more convenient for the construction.

development of mold flux for IF steel

2009, 25(01): 66-69,7. doi:

Asbtract ( 1494 )

Related Articles | Metrics

In light of the actual conditions of IF steel continuous casting in Panzhihua Iron and steel Company (PZHISC), an ingredient of the mold powder is designed and developed through the research upon effect of the basic materials and fluxes on the melt properties of mold powder as well as studies on the mode of preparation of the melting speed control materials. Industrial experiment has shown that the newly developed prefused mold powder can meet the demand of IF steel casting process in PZHISC, and it shows excellent properties such as a good melting behavior in mold and high rate of free of slab surface conditioning (98.5%) and less carbon pick-up (carbon pick-up in strand is controlled within the limit of about 2×10-6).

Development of new technologies and materials adopted in converter equipment

2009, 25(01): 70-72. doi:

Asbtract ( 584 )

Related Articles | Metrics

The present paper introduces development of the new materials and technologies adopted in the 180t top-bottom combined blown converter mainly including application of the unique cooling technology for the furnace cone, maintenance-free link rod suspension system, new multi-pipe plug and high temperature and creep-resistant materials.

Progress of research on inclusion induced surface defect of cold rolled plate

2009, 25(01): 73-77. doi:

Asbtract ( 656 )

Related Articles | Metrics

The demand for quality of the cold rolled plates is more and more stringent with development of electrical appliances and automobile industry. The surface defect caused by inclusion is one of the most common defects of cold rolled plate, which seriously affects the outward appearance of cold rolled plate and its the operational performance. In this paper, Sliver defect, cavity, and scar/pit, those three commonly encountered surface defects induced by inclusion are discussed and their characteristics and origin described, and the way to check them put forward.

Table of Content