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	2015 Vol. 50 No. 4
	Published: 2015-04-15

	1	CHU Shao-jun，CHEN Pei-xian，YANG Da-hai
		Feasibility of a new process for 300 series stainless steel with electrosilicothermic metallurgy
		A new method has been developed to produce 300 series stainless steel，which is mainly for producing stainless liquid steel with electrosilicothermic metallurgy. Ferronickel alloy with high silicon and low carbon content named as nickel-silicon ferroalloy is produced in submerged arc furnace （SAF） as the first step，then the slag containing chromium oxide and calcium oxide which come from refining furnace is charged into a shaking ladle together with liquid nickel-silicon ferroalloy for pre-desilication and certain chromium reduction，finally，the liquid alloy with other chromium concentrate and lime is charged into a refining furnace for final desilication to get the stainless liquid steel. In addition，a reductive dephosphorization before the pre-desilcation process could be carried out if necessary. Argon Oxygen Decarburization （AOD） or Vacuum Oxygen Decarburization （VOD） process could then be followed to produce planned stainless steel. This process is different from the traditional one since it takes advantage of the characteristics of low grade lateritic ore with high SiO2 content. Besides，the utilization of low cost chromium concentrate is another effective way for the reduction of production cost. Scale experimental results showed that the phosphorus content of nickel-silicon ferroalloy containing about 20% silicon content could be decreased below 0.03% by use of reduction dephosphorization process and with the utilization of nickel-silicon ferroalloy，chromium concentrate and lime as the main raw materials. It is possible to produce un-refined stainless liquid steel with electrosilicothermic process. Compared to traditional duplex process and based on matter and energy conservation，the total energy consumption，carbon dioxide emission and raw material cost in the new process could be decreased by about 7.1%，6.1% and 6.3%-7.2% ，respectively.
		2015 Vol. 50 (4): 1-7 [Abstract] ( 1285 ) [HTML 0KB] [PDF 0KB] ( 63 )

	8	SHI Shi-zhuang， DONG Qing-wen， BI Xue-gong， LI Peng，LUO Yong-hui， WANG Gong-er
		Experiment of coking process conditions on iron-coke properties
		At the ratio of iron ore powder of 10%，the influences of coking process conditions (bulk density，heating rate，soaking time) on iron-coke properties (porosity，mechanical strength，thermal property and reduction degree of iron ores) were investigated. The results show that，it is prominent for the coking process conditions to affect iron-coke properties: when bulk density of coal charge is 1.1 t/m3，the properties of iron-coke are excellent; when heating rate is 2.5 ℃/min，the mechanical strength and thermal property are optimal and the iron ore reduction degree increases along with increasing of heating rate; when soaking time ranges between 120-150 min，the properties of iron-coke are the best. Adjustment of the coking process conditions can produce the iron-coke with different properties.
		2015 Vol. 50 (4): 8-12 [Abstract] ( 1105 ) [HTML 0KB] [PDF 0KB] ( 69 )

	13	XU Zhang-yin，，ZHAO Zeng-wu，，JIANG Yin-ju，，LI Bao-wei，
		Experiment on Nb-bearing microalloyed steel made directly by Nb-bearing hot metal
		As a micro-alloyed element， Nb was recovered to made Nb-bearing microalloyed steel from Nb-bearing hot metal in a vacuum carbon tube furnace by decarburization and conversation of niobium with Fe2O3 oxidant at 1 500 ℃. The results show that when slag isn’t placed on the hot metal， silicon， niobium and carbon are oxidized simultaneously， which cannot make Nb-bearing steel. When basicity of SiO2-CaO-Al2O3 flux decreases， oxidation of silicon decreases， and decarburization is easy to complete in the molten iron and the oxidization of niobium is suppressed in the metal bath. By the way， carbon content of the molten iron is decreased to 0.032% and niobium content is decreased from 0.09% to 0.082%. When the basicity of SiO2-CaO-Al2O3 flux decreases， the lower silicon and niobium oxidize， the higher carbon oxidizes. On the other hand， when the vacuum of the furnace is lowed to 10 Pa， oxidization of silicon and niobium of Nb-bearing hot metal is suppressed and oxidization of carbon increases. By the test of the vacuum condition and acid SiO2-CaO-Al2O3 slag formed at 1 500 ℃， 50 kg scale experiments have been completed and it is important not only to provide laboratory findings of commercial test for recovery of niobium from Nb-bearing hot metal to make Nb-bearing microalloyed steel but also to provide a new method to recover Nb from Nb-bearing hot metal.
		2015 Vol. 50 (4): 13-16 [Abstract] ( 1253 ) [HTML 0KB] [PDF 0KB] ( 70 )

	17	ZHANG Ying-yi，，CHENG Xiang-li，QI Yuan-hong，ZOU Zong-shu
		Direct reduction of high-iron bauxite for recovery of nuggets and Al2O3
		Effects of the direct reduction process on the nuggets size and recovery percent were investigated by coal-based direct reduction and leaching process， and the effects of [(w(CaO)/w(Al2O3))] on the slag composition and leaching rate of alumina were investigated by the same way. The results show that when the [(w(CaO)/w(Al2O3))] is 1.7， [w(C)/w(O)] is 1.4， reduction temperature is 1 450 ℃， and the reduction time is 20 min， the nuggets size is biggest and the nuggets recovery percent is highest， the nuggets size and recovery percent are 11.5 mm and 93%， respectively. When the [(w(CaO)/w(Al2O3))] is 1.0， the furnace slag is mainly composed of gehlenite (Ca2Al(Al，Si)2O7)， when the [(w(CaO)/][w(Al2O3))] is 1.5， the furnace slag is mainly composed of gehlenite (Ca2Al(Al，Si)2O7)， dicalcium silicate(Ca2SiO4) and mayenite(Ca12Al14O33)， when the [w(CaO)/w(Al2O3)] is 1.7-1.9， the furnace slag is mainly composed of dicalcium silicate(Ca2SiO4) and mayenite(Ca12Al14O33). When the [(w(CaO)/w(Al2O3))] is 1.7 and leaching time is 2.0 h， the leaching rate of alumina is highest which is 87.5%， the leaching rate is increased by 9.4% than that of 0.5 h leaching time. Therefore， when the furnace slag is mainly composed of dicalcium silicate(Ca2SiO4) and mayenite(Ca12Al14O33)， it is more conducive toleaching of alumina.
		2015 Vol. 50 (4): 17-22 [Abstract] ( 1027 ) [HTML 0KB] [PDF 0KB] ( 56 )

	23	WU Bing-qiang，ZHANG Shu-hui，Lü Qing，LIU Xiao-jie，QIE Ya-na
		Effect of K，Na，Cl on softening property of hot blast stove refractory material
		Based on thermodynamic analysis， the distribution of K，Na and Cl in hot blast stove refractory material were analyzed. Causes of softening contraction of refractory material were studied and measures to avoid softening breakage were put forward. The results show that after seeping into the refractory materials， K and Na react with Al2O3 and SiO2 generating low melting point compound and HCl reacts with Al2O3 to generate gaseous chloride， which is the main cause of refractory materials softening contraction. Refractory materials surface treatment，using low chloride additives in sinter and changing broken bag in time are the main measures to prevent refractory materials from softening.
		2015 Vol. 50 (4): 23-26 [Abstract] ( 1075 ) [HTML 0KB] [PDF 0KB] ( 55 )

	27	REN Fei-fei，ZHANG Hui，WANG Wei-ning，WANG Ming-lin
		Numerical simulation of actual temperature field for chamfered mold copper
		Based on the dimension of chamfered mold，waterway arrangement，measured copper temperature，cooling water volume and temperature difference between inlet and outlet water in actual production process of Beijing Steel Plant，the commercial software ANSYS was used to simulate the chamfered copper mold temperature distribution in actual production. The results show that from the meniscus 0-300 mm，the lateral temperature distribution on narrow-surface cooper was W type，which is different from the right-angle mold inverted U type temperature distribution. From the meniscus 300-800 mm，the corner temperature decreases quickly，thus the temperature distribution was inverted U type，which is consistent with right-angle mold temperature distribution. In addition，the temperature gradient is relatively large in chamfered slope，and the heat-flux fluctuations between the solidified shell and copper is relatively large，which verifies the cracks occurred mainly in the chamfered slope，be consistent with the fact.
		2015 Vol. 50 (4): 27-33 [Abstract] ( 1434 ) [HTML 0KB] [PDF 0KB] ( 51 )

	34	TANG De-lin，LIU Xiang-hua
		Geometric?parameters in cross shear zone of asymmetrical rolling
		The calculation formulas of geometric parameters， such as neutral angles and cross shear ratio in asymmetrical rolling were found. Different types of deformation region in asymmetrical rolling were distinguished by the values of neutral angles. The influences of speed ratio， friction coefficient， entry thickness and reduction ratio on the value of cross shear ratio were analyzed by the formula for cross shear ratio established in this study. The cross shear ratio is one of the most important parameters in asymmetrical rolling which determines the rolling force the asymmetrical rolling can reduce. The cross shear ratio can also influence the permissible minimum thickness and the micro-structure of rolled piece. The formula to calculate the cross shear ratio provides the theoretical foundation for the parameter optimization of asymmetrical rolling process.The results of rolling experiment proved that the formulae for calculating the neutral angles and cross shear ratio are consistent with the reality.
		2015 Vol. 50 (4): 34-39 [Abstract] ( 1419 ) [HTML 0KB] [PDF 0KB] ( 70 )

	40	BAI Zhen-hua，，WANG Rui，，CUI Ya-ya，，CHANG Jin-liang，，XING Bai-xian，，DUAN Jian-gao
		Model and influence factors of strip transverse tension distribution in CAPL
		In allusion to the case that the on-line prediction of strip transverse tension distribution in CAPL cannot be realized，strip wandering，buckling and shape evolving cannot be warned which may lead to breakage. Taking into account the equipment and technological characteristics of CAPL，the CAPL strip tension distribution model was built and the relevant calculative strategy was given，on the foundation of analyzed the influence of the strip transverse temperature difference，the incoming strip shape，the furnace roll profile and the furnace roll perpendicularity and levelness error to the longitudinal elements deformation. Taking a CAPL of Baosteel Stainless Steel as an example，the influence of original furnace roll profile，incoming strip shape，transverse temperature difference，furnace roll perpendicularity and levelness error and assigned tension to the strip transverse tension distribution are analyzed. The forecast software of strip transverse tension distribution and shape evolving in passing of CAPL are compiled and applied to production and practice，which achieves good results，with further popularization and application value.
		2015 Vol. 50 (4): 40-47 [Abstract] ( 1417 ) [HTML 0KB] [PDF 0KB] ( 76 )

	48	CHEN Jian，，WANG Bing，HU Liang，LIU Qing-you，LIU Xiang
		Effects of hydrogen induced cracking on the microstructure of high strength pipeline steel
		The influence of microstructure on hydrogen induced cracking (HIC) of high strength pipeline steel was studied through scanning electron microscopy (SEM)， electron backscatter diffraction (EBSD) and other testing methods?from?two?aspects: organizational structure and grain boundary structure. The results indicate that high content and big block of M/A island will lead to obvious hydrogen induced cracking (HIC). Instead， the sensitivity of hydrogen induced cracking (HIC) will reduce through increasing the uniformity of organization. Furthermore， HIC of pipeline steel will grow along the large angle grain boundaries. On the contrary， HIC can be partly prevented on small-angle grain boundaries.
		2015 Vol. 50 (4): 48-52 [Abstract] ( 1328 ) [HTML 0KB] [PDF 0KB] ( 56 )

	53	TAO Hong-biao，ZHANG Hui，FAN Yi，WANG Ming-lin，MA Zhong-wei，ZHAO Pei
		Effect of cooling model on slab structure and internal crack of 0.1%C-5%Mn steel
		In order to reveal formation mechanism of slab internal crack of the 0.1%C-5%Mn steel， structure and crack feature of this steel have been researched under different cooling models by using methods such as physical test， metallographic examination etc and designing heat simulation experiment. The results show that a lot of martensite and crack appeared in the slab when the cooling intensity was high.The higher the cooling intensity， the more martensite phase had and the greater the crack width. By using soft cooling or hot charging process， the martensite transformation caused by rapid cooling could be prevented and granular bainite structure could be formed， which could control appearance and extension of the internal crack.
		2015 Vol. 50 (4): 53-57 [Abstract] ( 1201 ) [HTML 0KB] [PDF 0KB] ( 40 )

	58	MENG Xiang，SUN Ji-quan，CHEN Yin-li，LI Hui，XU Li-ming
		Effect of deformation on the phase transformation of Cr-Mo low alloy steel
		Cr-Mo low alloy steel has important applications in industrial production. CCT curve is an important basis for the research on the phase transformation of supercooled austenite. The deformation and cooling process were simulated by Gleeble-3500 thermal simulation tester and DIL 805 dilatometer in this paper. The superelement model was used to do the thermodynamic calculation and analysis. The results indicate that the deformation has a great influence on the phase transition free energy of Cr-Mo low alloy steel during the process of transformation， also on activity of carbon， mole fraction of carbon on phase boundaries， driving force of transformation and driving force of nucleation， which has an effect on the the incubation period and the degree of supercooling of the transition in the end. The measured results show that the incubation period and the degree of supercooling consistent with the theoretical calculated results. The deformation can also be used to enhance the critical cooling rate ferrite transformation. The finest ferrite grain can be obtained when the cooling rate is 0.3 ℃/s. Therefore， appropriate deformation and cooling process is of great importance in improving the microstructure and properties of Cr-Mo low alloy steel.
		2015 Vol. 50 (4): 58-62 [Abstract] ( 992 ) [HTML 0KB] [PDF 0KB] ( 54 )

	63	MA Jiang-nan，YANG Cai-fu，WANG Rui-zhen
		Influence of nitrogen addition on the microstructure and properties of vanadium microalloyed steel
		The influence of nitrogen addition on the microstructure and mechanical properties of vanadium microalloyed steel was studied. Experiment steels with different vanadium and nitrogen content were processed by thermal deforming simulation and rolled by laboratory roller respectively. OM， SEM and TEM were used to investigate the microstructure. Test results show that bainite laths and granular bainite are dominant in base vanadium microalloying steel. Intragranular ferrite trasnformation is promoted by nitrogen addition， which leads to acicular ferrite microstructure and refines the martensite-austeniete component. The toughness is improved as well. However， addition of vanadium increases precipitation strengthening， but has little effect on the morphology. The toughness is not improved. Vanadium precipitates in austenite as VN for nitrogen-rich steel. While for the nitrogen-low steels， it precipitates in ferrite as VC even if the content of vanadium is increased. The lattice misfit degree of austenite-ferrite， VC-ferrite and VN-ferrite are 6.72%， 3.89% and 1.55% respectively. It indicates that VN precipitated in austenite acts as preferential nucleation sites and promotes the intragranular ferrite transformation.
		2015 Vol. 50 (4): 63-69 [Abstract] ( 991 ) [HTML 0KB] [PDF 0KB] ( 42 )

	70	SHI Zhong-ran，WANG Rui-zhen，WANG Qing-feng，，SU Hang，CHAI Feng，YANG Cai-fu
		Microstructures and toughness of simulated CGHAZ of vanadium microalloyed steel
		Using the Gleele-3800 to simulate the thermal cycling process of coarse grained heat affected zone （CGHAZ）. When the weld heat input was 100 kJ/cm， comparing the CGHAZ microstructure and toughness of V steel， V-N steel， V-Ti steel， V-N-Ti steel， analyzed the vanadium and titanium carbon precipitation. The results show that the order of CGHAZ toughness from high to low is V-N-Ti steel， V-Ti steel， V-N steel and V steel; Adding Ti to V steel can effectively decrease the original austenite size; On one hand， increasing the nitrogen based on the V-Ti steel can promote the （Ti，V）（C，N）/TiN formed which can decrease the austenite size. On the other hand， increasing the nitrogen can promote the V（C， N） formed which can promote the polygonal ferrite formed. The polygonal ferrite can partly remedy the detrimental effect of the free N atoms and improve the CGHAZ toughness.
		2015 Vol. 50 (4): 70-75 [Abstract] ( 1368 ) [HTML 0KB] [PDF 0KB] ( 62 )

	76	LU Yan， NA Xian-zhao， QI Yuan-hong， ZHEN Chang-liang
		Dust control and engineering performance of stainless steel AOD slag
		Owing to the lattice transformation during cooling process， the expansion and pulverization of stainless steel AOD slag would happen. Then， it will result in dust pollution easily. And it is indicated that the lattice transformation from β-C2S to γ-C2S can be effectively controlled by injecting boron modified agents during the deslagging， and the pulverization rate of dust was reduced by 90.1%. The harmless treated stainless steel AOD slag can be used as cement mortar admixture as resource utilization， and the substitution rate for cement can be 0-30%. Meanwhile， according to the leaching toxicity test on AOD slag and its cement test block， the leaching of total Cr and Cr6+ were both reduced to below the standard value. Thus， resource utilization of the treated stainless steel AOD slag can be realized.
		2015 Vol. 50 (4): 76-83 [Abstract] ( 1249 ) [HTML 0KB] [PDF 0KB] ( 69 )

	84	JING Cai-liang，TIAN Zhi-hong，WANG Lei-chuan，HUANG Cai-de，WANG Chao-bin
		Shortening period of RH light treatment process and industrial practice
		In order to shorten the period of RH light treatment process of a domestic steel plant， sampling investigation was carried out in current process.Results showed that the apparent decarburization rate constant was hardly affected by the initial conditions， with the value of about 0.19 min-1;The Als/Alt of steel was low and had a big fluctuation at the beginning of pure cycling period， but increased gradually as increasing pure cycling time until to be a stable value. The optimum decarburization time and pure cycling time were suggested based on the present investigation. Industrial trials showed that the period of RH light treatment process could be reduced by 4 mins， furthermore， the cleanness of steel was good.
		2015 Vol. 50 (4): 84-87 [Abstract] ( 1297 ) [HTML 0KB] [PDF 0KB] ( 46 )

	88	QIU Hua-dong，，TIAN Jian-yan，YANG Shuang-qing，WEI Ai-xue，YANG Lian-hong
		Fusion modeling of the hot mill based-on case-based reasoning
		In view of the existing problems of poor adaptability for the small special steel grade modeling，based on the research of the foundation and optimization of existing hot mill model，a fusion modeling aiming at the small special steel grade in hot strip mill based on case-based reasoning was proposed combined with the mechanism-theory formula and advanced model control technology. According to the condition characteristics of small special steel grade，the model establishing process of the special steel grade rolling in hot strip mill with case-based reasoning was explained in details. With the practical production experience，this model has got continuous optimization，and the proper control parameter has been confirmed. This fusion modeling method can effectively enhance the control precision of the small special steel grade rolling and enhance the product quality.
		2015 Vol. 50 (4): 88-94 [Abstract] ( 1065 ) [HTML 0KB] [PDF 0KB] ( 54 )

	95	LI Li-xin，HUANG Ying-gang，ZHANG Kui，Lü Xiao-yuan，LI Bin，WU Xiao-dong
		Image feature and fractal on roll surface morphology in wear process
		The surface morphology of roll is directly related to the strip products’ surface quality and even the texture component. Quantitative monitoring of the morphological changes in the wear process of roll was researched in this study. Based on the MATLAB tool，the method of image processing was used to make pretreatment of roll surface morphology in different stages，and the study got 17 dimensional features of geometry，texture characteristics and fractal dimension. BP neural network model using to recognize the roll wear states was also established after parameters simplification. The results show that the image features， such as equal-area-cirde radius，circularity，texture entropy and second-order moment，and fractal dimension can be used as quantitative parameters to describe the surface morphology of roll. It’s also useful to use BP network model to recognize and judge surface morphology of roll wear. This study will supply a new approach to establish the quantitative evaluation system for the wear morphology of roll.
		2015 Vol. 50 (4): 95-101 [Abstract] ( 989 ) [HTML 0KB] [PDF 0KB] ( 67 )

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