Steelmaking

Technology optimization of co-injection desulfur for vanadium bearing hot metal

2013, 29(6): 1-4. doi:

Asbtract ( 293 )

Related Articles | Metrics

The application of co-injection desulfurization technology on the pretreatment of vanadium bearing hot metal in Chengde Steel was introduced.Some factors of the hit rate of target sulfur content and desulfurization rate were analysed.According to the situation of vanadium bearing hot metal,the co-injection parameters were optimized,the effect of desulphurization has been improved,and the average hit rate of target sulfur content can increase to 86.7 %.

Ladle desulphurization process with high intensity injection of magnesium

2013, 29(6): 5-8. doi:

Asbtract ( 270 )

Related Articles | Metrics

The article proves the reserves of desulphurization process with granulated magnesium due to its more diffuse injection and subsequent dispersion of flow in the hot metal. The results showed that the technological developments increase the heat and mass transfer surface in the refined bath at 33 %-50 %.It is increased the degree of absorption of magnesium, magnesium injection rate increases from 7-13 kg/min up to 16-25 kg/min, and the desulfurization process and slag skimming take only about 50 %-70 %of the converter smelting cycle. The parameters of injection process and the parameters of device structural have been determined and all the technological problems are solved by an injection device. The results of development has been used in the steel plant.

Practice on smelting process of 12Cr2Mo1 steel

2013, 29(6): 9-11,2. doi:

Asbtract ( 298 )

Related Articles | Metrics

Using the“EAF→LF→VCD→VC” process smelting 12Cr2Mo1 steel can effectively decrease the content of inclusions,and improving the purity of molten steel.The molten steel satisfied the requirements of composition can be got，through strictly controlling the content of S,P,Sn,As,Sb,ect in steel.The surface quality of steel ingot is good，the grain size and the level of nonmetallic inclusions satisfy the standard request.

Thermodynamic, kinetic analysis and application practice of manganese ore alloying in LF

2013, 29(6): 12-14,5. doi:

Asbtract ( 258 )

Related Articles | Metrics

Based on the disadvantages such as lower and unstable manganese yield, more factors influencing manganese ore alloying in converter, manganese ore alloying in LF was applied to raise the manganese yield. The metallurgical effect of manganese ore alloying in LF was discussed with thermodynamics and kinetics analysis. The reductive mechanism of manganese ore in LF was introduced. Some techniques and measures for increasing manganese yield were put forward. The practice results showed that the manganese yield reach 92 %, and the cost of steel decrease by 9.62 yuan/t for the manganese ore alloying in LF.

Mould taper optimization and application for CSP thin slab continuous casting

2013, 29(6): 15-18. doi:

Asbtract ( 297 )

Related Articles | Metrics

To control longitudinal crack breakout and reduce defects occurred such as surface longitudinal crack of slab, and scarring in CSP Plant of WISCO，combined scene production practice, the CSP special funnel shaped mould taper was optimized and studied. Considering mould copper special of funnel shaped structure and narrow surface wear and tear in using process, the taper on the basis of the foreign design was optimized. After optimization, the taper setting volume which compared to foreign provides increased by 15 %-25 %. After the new taper design put into action, the rate of longitudinal cracks breakout reduced to a lower level, and the appear rate of defects on slab surface such as longitudinal crack, scar, and so on are effectively controlled, and the quality of steel coils is improved.

Development of cable steel DL05

2013, 29(6): 19-22. doi:

Asbtract ( 245 )

Related Articles | Metrics

In light of problems of the low electrical conductivity and scab defects existing in trial production of cable steel DL05, the effects of content on wire rods quality were analyzed. Some improvments have been carried out involving reducing manganese content, controlling sulphur content in steel and other processing control measures, the results showed that the conductivity of rolling rod %IACA has been increased from 15.51 % to 16.58 % by means of w(Mn)≤0.19 % and w(Mn)/w(S)≥10 in steel and scab defects on rod surface decreased dramatically due to hot brittleness of wire rod. The quality of product meet the users’ demand, great suceess has been achieved on the development of cable steel DL05.

Change of slag and its effect on dephosphorization during BOF refining

2013, 29(6): 23-27,3. doi:

Asbtract ( 287 )

Related Articles | Metrics

The composition and mineralogy of slag formed during BOF refining were investigated by means of chemical composition,microstructure and phase analysis.Compared with final slag,intermediate slag has lower basicity,total iron (T.Fe) content,undissolved free CaO content and higher P2O5 content.Partition ratio of phosphorus between slag and metal in intermediate slag is also lower than that in final slag.There are mainly three phases observed in intermediate slag and final slag after solidification: MgO-(FeO+MnO) solid solution,CaO-FeO solid solution and 2CaO·SiO2-3CaO·P2O5 solid solution.Most phosphorus are enriched into the 2CaO·SiO2-3CaO·P2O5 phase in the slag.Partition ratio of phosphorus between slag and metal will increase at the initial stage of oxygen blowing by increasing ferrous oxide content and percentage of liquid slag in initial slag.By controlling slag basicity,the 2CaO·SiO2 phase will increase in final slag,and the partition ratio of phosphorus between slag and metal will increase at the end of oxygen blowing.

Optimization study on bottom blowing process in EAF

2013, 29(6): 28-30. doi:

Asbtract ( 250 )

Related Articles | Metrics

In order to explore the metallurgical interference of bottom blowing process in EAF，the physical simulation and stirring mechanism of bottom blowing process was studied，some industrial experiments have been conducted based on the 65 t EAF at Xining special iron and steel company.The results showed that the service life of porous plug brick reaches 623 times on the condition of keeping reasonable bottom blowing gas flow，so the porous plug brick and furnace shell can get the synchronization service life，the dynamics conditions of bottom blowing process is better，it is easier for the reaction to get balance，the consumption of steel materials reduced by 5.836 kg/t and the consumption of lime reduced by 10.827kg/t，decarburization rate increased by 0.011 %，so the bottom blowing process in EAF obtains a good metallurgical effect.

Research on cleanliness of SPHC steel produced by BOF→Ar→CC process

2013, 29(6): 31-36. doi:

Asbtract ( 320 )

Related Articles | Metrics

The shapes, sizes, quality and components of inclusions in coldrolled plate SPHC produced by“BOF→Arblowing station→CC”process were studied by systematic sampling in each step in steel production. Analysis methods mainly include total oxygen and nitrogen content analysis, optical microscopy, scanning electronic microscope(SEM),energy dispersive Xray spectroscopy (EDS),and slime(Electrolysis). The results indicate that：the total oxygen content is trending downward in the processes and the average mass fraction of total oxygen is 16.3×10-6 in slab; Inclusion compositions are basically distributed near the high Al2O3 in the whole process, more dispersive in slab which mainly contain Al2O3 inclusions, separate MnS inclusions and Al2O3-MnS, Al2O3-CaS, MnS-CaS composite inclusions. The size of inclusions is mostly less than 5 μm and the inclusion quantity density is 6.2/mm2 in the slab. Macroinclusions in steels mostly are composite inclusions of some or all of the elements of Al, Si, Ca, Ti, Mn, Mg. They mainly originate from external inclusions and secondary oxidation products, and parts of the inclusions contain K, Na elements, which shows that mold powder entrapment occurs .

Mathematical simulation on slag film structure of mould flux and preliminary application of production

2013, 29(6): 37-40,7. doi:

Asbtract ( 248 )

Related Articles | Metrics

In order to guide the practical production, the paper takes the slag film in the mold as the research object, and applies heat transfer theory to simulation analysis the variation regularity of slag film structure. The results show that: from meniscus down in the mold, liquid slag layer thickness increases first and then decreases, the crystal began to form as soon as the liquid slag film thickness decreases, with the decrease of temperature, crystallization is the end and vitreous body begins to form the layer of glass. At the same time, mathematical model is proposed theoretical significance for improving the quality of casting billet and optimization design of slag.

Quantitative research on cleanliness of unsteady continuously cast slabs

2013, 29(6): 41-47,5. doi:

Asbtract ( 290 )

Related Articles | Metrics

Aspex Explorer SEM was applied to investigate cleanliness of unsteady continuously cast IF slabs produced by the route “KR desulphurization→BOF dephosphurization→BOF decarburization→RH→CC”. The analyzed area of each slab sample ranges from 9 382.8 to 52 061mm2. The results indicate that there are five different types of nonmetallic inclusions in continuously cast IF slabs such as alumina cluster, alumina lump, spherical Al2O3·TiOx, entrapped mold powder, and bubble with alumina. Normal slabs have very high cleanliness with mass fraction of total oxygen changing from 0.001 0 % to 0.001 3 % and the density of inclusions bigger than 50μm is about 0.31/cm2. Entrapped mold powder is not found in such slabs. When the casting speed changes from 1.0 to 1.5m/min, the density of inclusions bigger than 50 μm decreases with the increase of casting speed. Among the unsteady continuously cast slabs, the quality of first slab is the worst and it cannot be used for auto and home appliance purpose which need high surface quality. The densities of inclusions bigger than 50 μm in the second slab, SEN exchange slab and last slab are higher than that of normal slabs. When they are used for auto purpose, they should be downgraded or scarfed. The qualities of ladle exchange slab and the last but one slab are the same level as normal slabs. They can be used for auto purpose.

Analysis of flaws detected by ultrasonic in heavy and medium steel plate

2013, 29(6): 48-52. doi:

Asbtract ( 247 )

Related Articles | Metrics

Various means were used to analyze flaws in the rolling samples of A709Gr50F steel which were detected by ultrasonic. Both the low magnification organization and the microstructures implicated that a large number of microcracks occurred in the thickness center of sample. They were mainly caused by banded structure and a long strip MnS plastic inclusions.

Optimization design of secondary cooling spray system of multi-slab billet caster

2013, 29(6): 53-56. doi:

Asbtract ( 285 )

Related Articles | Metrics

An optimization design method about the secondary cooling spray system of multislab billet caster was described. By the way of optimization design, spending only 10 h on exchange slabs and 30 min on ready for production. And it effectively solves the problem of poor quality of the slab, difficult equipment maintenance and breakout. The optimization design method provides handson experience for the reform or design of the same type of casting secondary cooling spray system.

丁满堂

2013, 29(6): 57-59,6. doi:

Asbtract ( 279 )

Related Articles | Metrics

In order to eliminate the hazards of fluoride, the low melting point and boosting substances of Li2O, BaO, B2O3 were added into the low carbon peritectic steel mold powder replaced fluoride. When basicity is 1.04, the melting point of the mold power is 1170.8 ℃, the crystallization temperature of it is only 1 159.3 ℃. It makes fluorinefree mold power successfully developed.

Erosion process of magnesia refractory by converter steel slag

2013, 29(6): 60-65. doi:

Asbtract ( 355 )

Related Articles | Metrics

Penetration and corrosion resistance of high purity MgO crucible by CaO-MgO-SiO₂-Fe₂O₃-P₂O₅ slag with different basicity at 1 600 ℃ were investigated by SEM,EDS,XRD and XRF analysis. At the test temperature, when w(CaO)/w(SiO₂)>2.5,Fe ions from slag diffused into the magnesia grain to form (Mg、Fe)O with high melting point. whereas another kind of minerals iron-containing 2CaO·Fe₂O₃ in molten slag would react with trace impurities Al₂O₃ located in the MgO grain interface to form 4CaO·Al₂O₃·Fe₂O₃ with low refractoriness, prompting silica rich local liquid dissolved into MgO grain. When w(CaO)/w(SiO₂)<2.5,experimental slag were not saturated with respect to MgO, so the MgO continually dissolved into molten slag until saturation state. Meanwhile, the slag mainly mineral phase were MgO·Fe₂O₃ and CaMgSiO₄. In this experiment, under 1 600 ℃ for 30 min, MgO concentration of slag (w(CaO)/w(SiO₂)=1) reached 18.23 %.It was suggested that crucible was seriously erosion.

Application of “WISDRI” dry purification and recovery technology of converter gas

2013, 29(6): 66-70. doi:

Asbtract ( 239 )

Related Articles | Metrics

The converter gas dry purification and recovery technology at home and abroad was discussed and analysed. The application of WISDRI dry purification and recovery technology of converter gas for the first time in Kunming Iron and Steel new converter, solves many engineering problems of the converter dry gas at high altitudes, and solves the problems of explosion in the dry gas system.

Review of control of MnS inclusions in steel

2013, 29(6): 71-78. doi:

Asbtract ( 361 )

Related Articles | Metrics

MnS inclusions can improve the machinability of steel. However, owing to the good deformation property, they will be elongated along rolling direction and transfer to large inclusions with big aspect ratio, which worsen the transverse property of steel products and easy to be sources of cracks. Thus, MnS inclusions in steel with small size, dispersive distribution and nearspherical or fusiform morphology are expected. A review of control of MnS inclusions on aspects of steel composition, continuous casting, rolling and heat treatment was made.

Table of Content