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	2019 Vol. 54 No. 9
	Published: 2019-09-15

	1	YU Yong，ZHU Ting-yu，LIU Xiao-long
		Progress of ultra-low emission technology for key processes of iron and steel industry in China
		The iron and steel industry has been the key field of the air pollution control in China， and the ultralow emission standard for the sintering and pelletizing of iron and steel industry has been proposed. The purification technologies for multiple processes such as sintering (pellet)，coking，blast furnace，and converter were summarized. The multipollutants ultralow emission technologies are based on the source reduction，process control，and endofpipe treatment，including the flue gas circulating，semidry desulfuration with medium and low temperature SCR denitration，activated carbon method，ozone oxidation with SO2 and NOx synergistic absorption，optimization of raw material structure of blast furnace for source reduction of SO2 and NOx，precharging bagtype dust collecting technology for the second flue gas of the converter. The above technologies have been applied in the iron and steel plants in China. Eventually，the advices such as greenization of production technology，rationalization of the pollutant measurement，strengthening the unconventional pollutants control，attaching greater importance to carbon emissions from the iron and steel industry are proposed.
		2019 Vol. 54 (9): 1-11 [Abstract] ( 478 ) [HTML 1KB] [PDF 2750KB] ( 1307 )

	12	WANG Bingxing，ZHU Fuxian，WANG Chao，LOU Haonan，
		Application of oxide metallurgy in high heat input welding steels
		In order to analyze the nucleation ability and different kinds of inclusions in oxide metallurgy steel and its effect on the improvement of high heat input welding properties，simulated welding thermal cycle on TiCa and TiMg steels were executed and industrial production by oxide metallurgy has been carried out. It was showed that the movement of austenite grain boundaries was retarded by TiMg oxides at 1 400 ℃ and held for 30 s. Acicular ferrites were also induced at cooling process. In order to keep the oxygen content of oxide metallurgy technology， SiMn predeoxidation and TiMg deoxidation process was built. EH420 experimental steel produced by new process with excellent welding ability， which can bear heat input of 200 kJ/cm by electrogas welding. Impact energy of HAZ at -40 ℃ was 200 J and numerous acicular ferrite plates were formed in the welded joint.
		2019 Vol. 54 (9): 12-21 [Abstract] ( 349 ) [HTML 1KB] [PDF 8163KB] ( 588 )

	22	WANG Chengyong, MEN Dongpo, CHEN Peng, LI Ziwen
		Nonlinear prediction model for caking index based on coal petrology
		In order to obtain an accurate and reliable prediction model for caking index of blended coal, two different coal mines in Hebei province were used as research objects. Prediction models of the caking index based on the coal petrographic blending utilizing nonlinear regression analysis were established. The macerals were effectively separated by the gravity separation method. The coal petrographic blending was carried out in low density products. The contents of different macerals were measured by a polarizing microscope. The results show that the molecular structure of the active component is moderate and contains a large number of active structures, which determines the caking index. The inert component forms the core and influences the caking index. With the increasing of the active component content and the decreasing of the inert component content, the caking index gradually increases. The S model, inverse model and progressive regression model based on the ratio between the reactive and the inert component had a higher fitting effect and accuracy. The regression model had the highest fitting degree, but the structure was complex. The inverse model had a simple structure and a good reliability, which could be used to predict the caking index of blended coal.
		2019 Vol. 54 (9): 22-26 [Abstract] ( 297 ) [HTML 1KB] [PDF 799KB] ( 681 )

	27	NIU Lele,LIU Zhengjian,ZHANG Jianliang,ZHANG Zongwang, WANG Yaozu,DU Chengbo
		Effect of mineral composition of iron ore on metallurgical properties of sinter
		In order to study the effect of the micromineral composition of the blended ore on the properties of sinter, the mineral composition of the iron ore powder was first analyzed by XRD refinement, then the sintering pot test was designed, and the metallurgical properties of the obtained sinter were detected and the microstructure of the sinter was observed. The obtained results are as follows. The hematite and quartz could increase the softening start temperature. The hematite is also beneficial to the reducibility of sinter. The kaolinite is not conducive to the maintenance of reducibility of sinter, and also reduces the softening start temperature of sinter, and makes the melting temperature interval increase. As the content of goethite increasing, the lowtemperature RDI of sinter decreases first and then increases. In terms of mineral phase structure, the goethite is more likely to form the acicular calcium ferrite than hematite. The SiO2 produced by kaolinite decomposition is more active than quartz and is more likely to form the silicate phase. It is concluded that the hematite, goethite, kaolinite and quartz in the blended ore have a significant impact on the properties of sinter.
		2019 Vol. 54 (9): 27-32 [Abstract] ( 406 ) [HTML 1KB] [PDF 2657KB] ( 743 )

	33	LU Yanan,WU Shengli,WANG Laixin,KOU Mingyin
		Analysis of chemical compositions of slag affecting #br# desulphurization in hot metal of COREX process
		The COREX process has many advantages, such as the less pollution, the lower energy consumption and the lower dependence on the metallurgical coke, while it still has the disadvantage of the high sulfur level in the hot metal.To improve the desulfurization efficiency in the COREX3000 process, several aspects are studied and practiced.The work focuses on the effects of chemical compositions of slag, such as w(CaO)/w(SiO2)、w(MgO) and w(MgO)/w(Al2O3) on the desulfurization efficiency. The influences of chemical compositions of slag on the desulfurization efficiency and the sulfur distribution ratio are studied through experimental studies, and the optimal chemical compositions of the slag are listed. Comparing the effects of two kinds of basic oxides on the desulfurization efficiency, the binary basicity of slag should be preferentially adjusted within 1.201.35, and then w(MgO) of slag should be controlled. It is also necessary to take care of the appropriate w(MgO)/w(Al2O3) at about 0.800.90.
		2019 Vol. 54 (9): 33-38 [Abstract] ( 291 ) [HTML 1KB] [PDF 1122KB] ( 614 )

	39	ZHANG Jian
		Quantitative analysis of hot metal composition and TiO2 load #br# for effective furnace maintenance in Shougang Jingtang
		The abnormal temperature rise of the hearth side wall of a blast furnace is a hard nut to crack for many enterprises. Currently, the furnace maintenance by adding titanium ores is a widely used technique. In order to achieve the effective furnace maintenance free of the titanium ore waste, and to protect the blast furnace condition from the pessimistic effect of the excessive titanium ore，the quantification of suitable mass percent of Ti in the hot metal is made according to the change of the hearth side wall temperature of blast furnaces in Shougang Jingtang. And the ranges of the mass percent of Si in the hot metal and the charged TiO2 load are narrowed down by linear regression analysis. The results indicate that w(Ti) and w(Si) in the hot metal and the charged TiO2 load of the No.1 BF should be controlled in ranges of 0.055%0.080%,0.20%0.35% and (6±0.5) kg/t, respectively. While the three parameters mentioned above of the No.2 BF are 0.08%0.13%,0.30%0.45% and (7±0.5) kg/t, respectively. More importantly, the more effort should be devoted to stabilizing the smelting temperature in the actual production to the protect hearth side wall. In addition, a good activity of the dead stock, a standard operation in the cast house and a rational cooling system are necessary.
		2019 Vol. 54 (9): 39-43 [Abstract] ( 314 ) [HTML 1KB] [PDF 1050KB] ( 776 )

	44	LIN Jie, YANG Cheng, WANG Yuanming, MOU Fenyun, HOU Dong, WANG Deyong
		Deoxidation thermodynamics in electroslag remelting process
		In order to investigate the deoxidation during electroslag remelting process, a thermodynamics model for the deoxidation in Cr5 system with Al as a deoxidizer was developed based on the ion and molecule coexistence theory (IMCT), the thermodynamics equilibrium and the mass conservation law. The equilibrium mass percent of Si, Al, Mn in the steel were obtained depending on the increasing mass percent of Al， which provided a theoretical basis to control the Al addition based on the variation curves of mass percent of Si, Al, Mn in the steel and the composition required by the certain steel. The result shows that the mass percent of Si, Al, Mn and Al2O3 increase with the mass percent of Al increasing, while the mass percent of SiO2, FeO and MnO tend to decrease. Considering the limitation of Si, Al, Mn mass percent, the amount of Al added in the steel should not exceed 0.17% of the steel.
		2019 Vol. 54 (9): 44-49 [Abstract] ( 186 ) [HTML 1KB] [PDF 887KB] ( 598 )

	50	ZHOU Zhenyu, TANG Ping, ZHOU Zunchuan, HOU Zibing, WEN Guanghua
		Optimization on nozzle parameters of 200 t combined blowing vanadium extraction converter
		Enhancing the mixing capability of top blowing on 200 t combined blowing vanadium extraction converter by optimizing the performance of oxygen lance nozzle was focused，and a physical simulation system was built to optimize the angle，hole number and Ma number of nozzles by studying their effects on the molten pool stirring in various lance height and bottom blowing flux. The results showed that the mixing time decreased and the 1/3 big wave height increased with the hole angle decreasing first, and these two laws turned to opposite trend when the angle was 12°. The mixing time of 12° nozzle was 4.17% smaller than that of original 13° nozzle, and the 1/3 big wave height was 4.21% bigger. The mixing time and the 1/3 big wave height of the 5holenozzle case were 1.88% and 3.35% smaller than those of the 4holenozzle case respectively, and conductivity measurements showed there existed a dead zone in the molten pool of the 5holenozzle case. The mixing time of the nozzle with Ma number 2.10 and 2.20 were 7.36% and 14.31% smaller than those of the nozzle with Ma number 1.99, and the 1/3 big wave height were 8.68% and 14.75% bigger. The order of the affection extent of each parameter was as follow, Ma number> Nozzle hole angle> Nozzle hole number. The optimization results turned to be more outstanding when the bottom blowing flow rate remains low. The industrial application of the optimized nozzle (with 4 hole, 12° and Ma number 2.10) showed the residual w(［V］) in semisteel reduced by 18.8%, the percent of heats with residual w(［V］) ≤0.05% increased by 26.7%, w((V2O5)) in the slag increased by 6.5% and w((TFe)) decreased by 6.6%.
		2019 Vol. 54 (9): 50-56 [Abstract] ( 301 ) [HTML 1KB] [PDF 1982KB] ( 1064 )

	57	CAI Jun1,ZENG Jiaqing1,LIANG Qiang1,HUANG Xiaoli2,ZHANG Bo1，ZHAO Bin1
		Cold state simulation experiment on powder injection speed #br# control of metallurgical dispenser
		In order to achieve the powder injection speed control of metallurgical dispensers, the effects of injection parameters on the pressure inside the dispenser and the pressure of powder injection pipeline was determined and the control law of the difference (Δp) between the pressure inside the dispenser and the pressure of the powder injection pipeline on the injection speed was studied by means of cold state simulation experiments. The results showed that the pressure inside the dispenser was mainly determined by the top pressurized gas pressure and the fluidized gas pressure under the normal powder injection condition. The pressure of the powder injection pipeline was mainly determined by the carrier gas flow and increased with the increasing of the carrier gas flow. Through setting different combinations of injection parameters such as the value of top pressurized gas pressure, the value of fluidized gas pressure and the value of carrier gas flow, the Δp was changed, then the steady control of the powder injection speed was achieved. Under the same condition of the carrier gas flow rate, the powder injection speed increases with the increasing of the Δp; under the same condition of Δp, the larger carrier gas flow, the greater powder injection speed.
		2019 Vol. 54 (9): 57-61 [Abstract] ( 245 ) [HTML 1KB] [PDF 1245KB] ( 607 )

	62	XIAO Zunhu1，LIU Peng2，XU Gangjun2，ZHOU Junjun2，SUI Yafei2
		Selection of calcium treatment technology of LF #br# refining for different steel
		In order to optimize LF refining calcium treatment process for different steels，the evolution mechanism of inclusions in high strength structural steel，low carbon structural steel，welded cylinder steel，wear resistant steel and high carbon steel during LF refining and calcium treatment was investigated. The results show that the longer the slagsteel reaction time，the more thorough the inclusion modified before calcium treatment. Before calcium treatment，Al2O3 is the main inclusion of welded cylinder steel，MgOAl2O3CaO composite is the main inclusion of high strength structural steel and low carbon structural steel，and Al2O3CaO inclusion with low melting point is the main inclusion of high carbon steel and wearresistant steel. The amount and the size of inclusions in molten steel can be increased in the process of calcium treatment. The key to control Al2O3SiO2MnO composite inclusions is to avoid SiMn alloying in the middle and late stages of LF refining. Considering all factors，it is suggested that the current amount of feeding calcium wire should be increased for welded cylinder steel，light calcium treatment process should be used for high strength structural steel and low carbon structural steel，and calcium treatment process should be cancelled for high carbon steel and wear resistant steel.
		2019 Vol. 54 (9): 62-72 [Abstract] ( 359 ) [HTML 1KB] [PDF 15394KB] ( 524 )

	73	ZHANG Hongliang，FENG Guanghong，CUI Huaizhou
		Analysis of crack defects in Q420B angle steel #br# during hot rolling process
		In order to solve the problem of more folding and scratching in the hot rolling process of Q420B largesize angle steel， the numerical simulation method is used to study the deformation characteristics of W butterfly type. By modifying the hole profile of the fifth pass of the W butterfly type， the surface quality problems in the production process of largesize angle steel have been significantly improved. The results show that a larger size of angle steel can be rolled out with a smaller billet by the Wpass system，but the angle steel needs to be bent several times for the Wpass system. Due to the violent metal flow on the surface，the steel is easy to produce surface quality defects. When the W butterfly pass is used to roll the No.22 angle steel，the fold tends to occur in the sixth pass. After the pass optimization，the rates of scratches and folding defects are obviously reduced.
		2019 Vol. 54 (9): 73-78 [Abstract] ( 278 ) [HTML 1KB] [PDF 5864KB] ( 599 )

	79	LI Xiujun1，2，CUI Yaya1，3，BAI Zhenhua1，4
		Online control technology of emulsion volume percent in double cold reduction mill
		In light of the enormous force fluctuation during the rolling acceleration and deceleration in the double cold reduction mill. After fully considered the equipment and technological characteristics of the emulsion direct application system，the effect of rolling velocity and emulsion concentration on the plateout oil film thickness，deformation zone oil film thickness，friction coefficient，forward slip，rolling force was analyzed. On this basis，the relationship between the emulsion lubrication and the rolling velocity was established. Subsequently，an online control technology of the emulsion concentration in double cold reduction mill was developed by adjusting the emulsion concentration in real time during the rolling acceleration and deceleration in the double cold reduction mill. Then，this technology was applied in a 1 220 double cold reduction mill，reduced the force and thickness fluctuation effectively and improved the rolling stability and product quality，which has further popularization and application value.
		2019 Vol. 54 (9): 79-84 [Abstract] ( 326 ) [HTML 1KB] [PDF 994KB] ( 768 )

	85	CHEN Hao1，2，XU Haifeng2，ZHOU Tianpeng1，2，CHEN Zejun1，
		Effect of quenching and low temperature treatment on microstructure and properties of X30 CrMoN 15 1
		In order to explore the optimum quenching and cryogenic treatment process for X30 CrMoN 151 high nitrogen martensitic steel，the effects of different quenching temperatures and cryogenic treatment on the microstructure and properties of high nitrogen steel were studied by OM，XRD，SEM，EDS and EBSD. The results show that when the austenitizing temperature is lower than 1 050 ℃，the original austenite grain growth is slow，and when the austenitizing temperature is higher than 1 050 ℃，the grain grows sharply. As the austenitizing temperature increasesed，the carbide dissolution increases，and the retained austenite increases linearly after quenching in oil. After the low temperature treatment，the retained austenite decreases greatly，and the higher the austenitizing temperature，the more the retained austenite drop after cold treatment. The hardness of the steel increases first and then decreases with the austenitizing temperature，and the hardness is highest at 1 000 ℃. After the low temperature treatment，the hardness first rises and then decreases with the austenitizing temperature，and the hardness is highest at 1 030 ℃. The impact toughness of steel increases first and then decreases with austenitizing temperature. The impact toughness is best at 1 030 ℃. After low temperature treatment，the impact toughness of steel decreases greatly.
		2019 Vol. 54 (9): 85-93 [Abstract] ( 375 ) [HTML 1KB] [PDF 12354KB] ( 655 )

	94	GAO Xiangming1，PEI Mingde1，2，LI Guoping1，2
		Influence of cold rolling on precipitation of S32750 super duplex stainless steel
		To optimize heating process and avoid precipitating harmful phase within cold plates，the effect of cold hardening on precipitation of S32750 plate was studied. Super duplex stainless steel S32750 plates were heated at 850 ℃ after different cold deformation. The precipitations were studied by SEM，EDS，XRD and TEM. The result shows that the amounts of precipitation increases with the cold deformation increasing，when the cold deformation rate bigger than 50%，the ferrite phase almost filled with precipitation. The precipitations almost are sigma phase，except for small amount Cr2N，χ phase and γ2. σ and χ phase were precipitated at the phase boundary and ferrite phase，Cr2N is precipitated at the phase boundary and secondary austenite in the ferrite with the Sigma phase. The dislocation density increases with the cold deformation increasing，which lead to the precipitation speeding up.
		2019 Vol. 54 (9): 94-98 [Abstract] ( 334 ) [HTML 1KB] [PDF 7063KB] ( 517 )

	99	LI Ziyun1，DENG Peichang2，HU Jiezhen1，WANG Gui1，LIU Quanbing2
		Corrosion law of cold rolled steel plate in tropical ocean atmospheric environment
		Temperature，relative humidity and Cl- content are the main factors affecting the corrosion of cold rolled steel sheets in marine atmospheric environment. In order to study the influence of environmental factors on the rusting time of coldrolled steel sheets stored in warehouses in tropical ocean atmosphere，the corrosion observation experiments of coldrolled steel sheets were carried out in an indoor simulation device with temperature，relative humidity and Cl- concentration as variables. At the same time，the corrosion observation experiments of coldrolled steel sheets were carried out in the warehouse of coldrolled products in iron and steel works. The results show that the results of indoor simulation experiment and field experiment are in good agreement，and the corrosion characteristics and rules of coldrolled steel plate in warehouse can be studied by indoor simulation experiment. The relationship between rusting time of cold rolled steel sheets and relative humidity of atmospheric environment is linear when the temperature is in the range of 2030 ℃，and exponential when the temperature is in the range of 3545 ℃. The critical relative humidity of coldrolled steel plate decreases with the increase of temperature.
		2019 Vol. 54 (9): 99-105 [Abstract] ( 250 ) [HTML 1KB] [PDF 2500KB] ( 614 )

	106	SONG Yanpei1，2，WANG Huigai2，LI Li1，SU Ming1，YOU Long2
		Effect of modification treatment on microstructure and properties #br# of wear and corrosion resistant cast iron
		For improving service properties of the materials in the condition of cement concrete stirring and conveying，a newly developed wear and corrosion resistant cast iron were taken as the research object. Effect of addition amount of the complex modifier on microstructure，mechanical properties and corrosive wear property of the wear and corrosion resistant cast iron were investigated by complex metamorphic treatment. The experimental results show that the compound modification can refine the matrix microstructure，eliminate columnar dendrite grain in the matrix microstructure，change the carbide morphology，size and distribution，diminish the harm of coarse flake carbide on the wear and corrosion resistant cast iron matrix，and which increase mechanical properties and corrosive wear resistance. The addition of more complex modifier can significantly enhance the toughness and corrosive wearresistance. Compared with the unmodified wear and corrosion resistant cast iron，impact toughness and corrosive wear resistance of the wear and corrosion resistant cast iron modified by 0.25% and 0.50% complex modifier are increased by 22.9%，58.3% and 16%，23% respectively，and hardness have a little change，which has achieved the expected goal.
		2019 Vol. 54 (9): 106-109 [Abstract] ( 279 ) [HTML 1KB] [PDF 3702KB] ( 516 )

	110	ZHANG Xinning
		Effect of graphite nodules on fracture of ductile cast iron #br# under low temperature impact loading
		In order to clarify the microscopic fracture mechanism of ductile cast iron used under low temperatures，the effect of graphite nodules on fracture evolution process under low temperature impact loading was studied，which was proposed to provide further development of low temperature ductile iron material and failure assessment. The impact fracture morphology was analysised by using SEM and confocal laser scanning microscope. The results of quantitative fractography indicate that both Sa and Rc/R0are decreased with temperature during the impact fracture process. The cracks initiate from the interface between nodular graphite and the matrix. Therefore，in the spheroidization process，attention should be paid to improving the microstructure of the interface between the graphite and the matrix.
		2019 Vol. 54 (9): 110-115 [Abstract] ( 292 ) [HTML 1KB] [PDF 8535KB] ( 538 )

	116	LIU Xiang，DU Qunli，LI Xin
		Effect of heating process on grain growth of#br# NbTi microalloyed steel
		In order to understand the effects of heating schedule on the austenite grain growth and precipitation behavior，the OM，TEM and EDS were used for studying austenite grain coarsening behavior and microalloying carbonitrides precipitation behavior of NbTi test steel at different of heating temperature(1 150，1 200 and 1 250 ℃) and holding time(0.5，1.0，2.0 and 3.0 h). The experimental results showed that the austenite grain size grew up gradually with the increasing of heating temperature，and the austenite grain grew rapidly when the heating temperature exceeded 1 200 ℃. With the increasing of holding time，the average austenite grain grew up gradually，and the austenite grain grew rapidly when the holding time exceeded 2.0 h. EDS results showed that the precipitates are composite phase (Nb，Ti)(C，N)，however the amounts of precipitate was reduced and the sizes of precipitate increased at higher heating temperature and longer holding time，consequently，the effects of precipitate on austenite grain was decreased. The heating temperature at 1 1501 200 ℃ by holding less than 2.0 h will be more appropriate for NbTi test steel.
		2019 Vol. 54 (9): 116-120 [Abstract] ( 304 ) [HTML 1KB] [PDF 5218KB] ( 498 )

	121	HAN Yi1，ZENG Huimin1，WEN Huaiyu1，XIAO Yao1，YU Enlin1，ZHAO Yuqian2
		Effect of coil structure on induction heating #br# process of heavyduty sprocket
		The sprocket is one of the basic transmission parts in the field of metallurgical engineering，and the surface strengthening treatment is an important way to improve the life of the sprocket. The approximate sprocket heating layer can be obtained by the electromagnetic heating of the sprocket with a bevellike contoured coil. However，the uneven distribution of the magnetic field strength becomes the root cause of the nonuniformity of the sprocket temperature，due to the combined effect of the ring effect and the proximity effect. Controlling the proper distribution of magnetic force lines in space is still a key factor in achieving high heating quality. The sprocket induction heating mechanism was researched，and the multicoordinate precise control simulation model was established. The effect law of the induction coil structure parameters on the heating quality was analyzed and it was found that the adjustment of the coil angle，the root radius and the tip distance could reduce the maximum temperature difference of the tooth profile by 1/3 than the full contour coil.
		2019 Vol. 54 (9): 121-131 [Abstract] ( 291 ) [HTML 1KB] [PDF 8431KB] ( 579 )

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