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	2018 Vol. 53 No. 2
	Published: 2018-02-15

	1	WANG Xin-dong，TIAN Jing-lei，SONG Cheng-yuan
		Innovative practice technology and outlook in large iron and steel enterprise green manufacturing
		Green steel is the common choice and development direction of the world’s iron and steel industry. Faced with the increasingly stringent regulations and requirements on energy conservation and environmental protection，consumption reduction and emission reduction，the steel industry has accelerated the reform and innovation in green manufacturing processes，technologies and equipment. Based on the stage achievements of some large iron and steel enterprises in energy saving，emission reduction，resource utilization and technological innovation in recent years，the progress of greening process in the green industry such as coking，sintering，ironmaking，steelmaking，and auxiliary processes was summarized. According to the “six in one” overall arrangement，the big business focuses on the green development thought，and carries out ten green leading technologies by hosting and participating in the national key subjects in order to constantly lead green and intelligent development in the iron and steel industry.
		2018 Vol. 53 (2): 1-9 [Abstract] ( 496 ) [HTML 1KB] [PDF 1131KB] ( 1292 )

	10	LIU Ying，LI Zheng-yi，，DI Zhan-xia，，LONG Hong-ming，，CHUN Tie-jun，，WANG Ping，
		Effects of reducing condition on apparent porosity and metallization degree of COREX pellets
		The metallization degree of pellets is an important indicator in the COREX reduction process， and the apparent porosity of pellets after reduction significantly affects the reduction condition of pellets in COREX shaft furnaces. Effects of reducing condition on apparent porosity and metallization degree of COREX pellets were investigated under simulating load reduction of COREX， and the metallization degree and the apparent porosity of coated pellets whose surface coated the coating material after reduction， were analyzed for easing the sticking phenomenon of COREX shaft furnace. The experimental results indicate that the increase of the apparent porosity of the pellets is beneficial to the increase of the metallization degree. With the temperature increasing from 800 to 900 ℃， the metallization degree increases， at the same time the apparent porosity increases. When the volume percent of H2 in the reducing gas increases， the metallization degree and the apparent porosity of the pellets also increases. When the volume percent of H2 increases by 5%， the metallization rate increases by 2.6% after reduction. At 850 ℃， the apparent porosity and metallization degree of the reduced coating pellets which coat the light burden dolomite mix plastic with the ratio of 1[∶]1，are 53.8% and 60.2% respectively.
		2018 Vol. 53 (2): 10-13 [Abstract] ( 383 ) [HTML 1KB] [PDF 848KB] ( 801 )

	14	YAN Long-fei，SHI Xue-feng，ZHAO Kai，HU Chang-qing，LONG Yue
		Experiment on direct reduction of gas-based shaft furnace of high phosphorus oolitic hematite
		According to the present situation of Low utilization rate of high phosphorus oolitic hematite， XRD and SEM were used to analyze the ore composition and phase structure of high phosphorus oolitic hematite， and it was suggested that the gas based direct reduction process should be adopted to deal with such ore according to the analysis results. The effects of reduction temperature， reduction time， reducing atmosphere and reducing gas content on the metallization rate in the direct reduction process of high phosphorus oolitic hematite were systematically studied and analyzed. The results indicate that metallization rate can reach 92.10%， when reduction temperature is 1 100 ℃， the reduction time is 4 h， gas flow is 2 600 m3/h and the ratio of volume percent of H2 and CO at reducing atmosphere is[φ(H2)∶][φ(CO)＝]1[∶]1.
		2018 Vol. 53 (2): 14-19 [Abstract] ( 367 ) [HTML 1KB] [PDF 1189KB] ( 732 )

	20	ZUO Hai-bin，GUO Long-fei，WANG Ya-jie，ZHENG Jin
		Effect of bosh angle and shaft angle on gas distribution in blast furnace
		Rational gas distribution is the primary factor for blast furnace to maintain the stable production with high efficiency and low consumption. The gas distribution is affected not only by the qualities of burden and operating rules，but the inner profile of blast furnace. As the innate factor，the rational inner profile design is the basis of acquiring the ideal gas distribution. Depending on the theories of heat transfer and hydromechanics，mathematics models of heat transfer and gas flow in blast furnace were established，and the critical parameters were obtained through experiments. Subsequently，the effect of bosh angle，shaft angle and equivalent bosh angle on the gas distribution were studied through numerical simulation method. The result indicates that decreasing bosh angle and increasing shaft angle are in favor of suppressing the edge flow. And adjusting the equivalent bosh angle can achieve the same destination as well，but which plays a role with higher intensity and wide range compared to the bosh angle adjustment，also with a different maximal affecting position to gas flow.
		2018 Vol. 53 (2): 20-26 [Abstract] ( 738 ) [HTML 1KB] [PDF 1045KB] ( 1556 )

	27	DENG Zhi-yin，ZHU Miao-yong
		Analysis on source of MnO/FeO containing macro-inclusions in alloyed steel
		The aim of the present study is to find the source of MnO/FeO-containing macro-inclusions on the basis of the results of slime method and industrial trials. According to the comparison with micro-inclusions in steel， it is found that there is no obvious relationship between MnO/FeO-containing macro-inclusions and micro-inclusions in steel. Thermodynamic calculation also rules out the possibility that those inclusions are formed by the reoxidation of liquid steel， and it is confirmed that the MnO/FeO-containing macro-inclusions are from ladle filler sands and their sintering products based on the compositions of macro-inclusions and the sintering behaviors of ladle filler sands. When ladle filler sands fall into liquid steel， it is very difficult to remove from tundish， even after the middle casting stage of each heat. Therefore， at the beginning of the teeming stage of each heat， the removal of ladle filler sand becomes a very important step to control macro-inclusions during industrial process.
		2018 Vol. 53 (2): 27-31 [Abstract] ( 321 ) [HTML 1KB] [PDF 937KB] ( 740 )

	32	LI Jiao，YU Hui-xiang，WANG Xin-hua，GAO Pan，LI Hai-bo
		Optimization of arrangement of bottom tuyeres through numerical simulation
		In order to optimize stirring effect of converter bottom blowing， based on the converter in a steel plant， a three-dimensional Euler mathematical model was established through the commercial software Ansys-Fluent to study the effect of the number of bottom tuyeres on the mixing behaviors of the molten metal in converter. The results indicate that with 4 bottom tuyeres and large flow through each tuyere， the recirculation zone develops fully and the blocking of tuyeres can be controlled. Meanwhile， the average velocity of the molten metal is large， the coverage of weak zone， low velocity zone and dead zone are small and the mixing time is short. Therefore， 4 bottom tuyeres is the best number of the bottom tuyeres. For the distribution of 8 and 12 bottom tuyeres arranged closely， the flow fields are similar to the one of 4 tuyeres， but the energy utilization rate is lower. The arrangement of multiple tuyeres is beneficial to the mixing of upper half of the molten pool. However， with more bottom tuyeres， the flow rate of the gas through per bottom tuyere is smaller， so the mixing effect at the bottom of converter is bad. Practices show that the technical indexes of the converter are greatly improved at the end of smelting when using the arrangement of 4 bottom tuyeres， which is consistent with the results through numerical simulation.
		2018 Vol. 53 (2): 32-39 [Abstract] ( 443 ) [HTML 1KB] [PDF 2104KB] ( 924 )

	40	CUI Ya-ya，LI Bo-yang，BAI Zhen-hua，，CUI Xi-ying，LI Xiao-feng，XU Ji-shuan
		Comprehensive optimization setting of emulsion flowrate and concentration for double cold reduction mill
		In light of the problems that researches on the lubrication and oil consumption of direct application system were very few in the double cold reduction mill，the emulsion flow and concentration were set separately，and therefore the lubricity and oil consumption could not be fulfilled simultaneously， the emulsion flowrate and concentration comprehensive optimization technology for direct application system of double cold reduction mill was developed with oil consumption fixed mode and lubricity assured mode based on the equipment and technological characteristics of the direct application system of the double cold reduction mill，which considers the steel grade and specifications. The corresponding software of emulsion flowrate and concentration comprehensive optimization technology was compiled and applied to the production practice of a 1 220 double cold reduction mill，which achieves good results，with further popularization and application value.
		2018 Vol. 53 (2): 40-44 [Abstract] ( 338 ) [HTML 1KB] [PDF 630KB] ( 785 )

	45	YANG Jun，GAO Jian-hong，YANG Qi-yu
		Effect of hot-rolling technology on surface chromatic aberration defects for Ti precipitation strengthened steel
		The surface chromatic aberration of precipitated steel with high Ti content in cold rolling affects surface quality. The effect and mechanism of hot rolling technology on surface chromatic aberration was discussed. The surface chromatic aberration is caused by the difference of grain size on the surface of the strip. In the process of hot rolling，the precipitation of Ti phase particles in the surface is different，which makes the grain refinement different in the annealing process and causes the surface chromatic aberration. The tests about the effect of different finish rolling temperatures and coiling temperature on surface chromatic aberration show that the low rolling temperature is conducive to the improvement of chromatic aberration defects，but the coiling temperature on the surface chromatic aberration is not obvious，and the best finish rolling temperature is 860 ℃.
		2018 Vol. 53 (2): 45-49 [Abstract] ( 347 ) [HTML 1KB] [PDF 1256KB] ( 901 )

	50	LU Heng-chang，HU Chun-dong，WANG Cun-yu，PU En-xiang，LIU Jian-hui，DONG Han，
		Kinetics of massive transformation for an ultra-low carbon steel containing niobium
		For investigating the transformation mechanism and kinetics of an ultra low-carbon high niobium steel（0.002C-0.52Nb）, the dilatometry was employed by continuous cooling process. The microstructure was observed by OM and SEM. A modified Johnson-Mehl-Avrami（JMA）kinetics model was used to calculated the migration velocities of the advancing interface.The results show that the transformation mechanism for various cooling rates is massive transformation. The massive ferrite is characterized by zigzag grain boundary and the product can across the initial austenite grain boundary. The calculated interphase velocity is approximately constant with a mean value of （0.65，1，1.7，6.2）×10－5 m/s for 3，5，10，30 ℃/s respectively，which is proportional to cooling rate，implying that the employed model is available to massive transformation of the investigated steel. The solute niobium seems to have some effects to decrease the interphase migration velocities compare to that reported in literatures.
		2018 Vol. 53 (2): 50-54 [Abstract] ( 396 ) [HTML 1KB] [PDF 1505KB] ( 802 )

	55	ZHU Rui-qi，SONG Xin-li，ZHENG Ai-qin，CHEN Rong-dong，JIA Juan，FAN Li-xia
		Strain hardening and microstructure characteristic of high strength IF bearing phosphorus steel
		In order to research the strain hardening characteristic of high strength IF bearing phosphorus，the stress-strain curve is measured by tensile testing machine and the microstructure，textile，slip band，dislocation are analyzed by optical microscope，scanning electron microscope，transmission electron microscope respectively. The results showed that the polygonal ferrite grain were obtained of the high strength IF steel bearing 0.056% phosphorus annealed at 810 ℃ for 120 s. The yield strength of the high strength IF steel bearing was 212 MPa and tensile strength was 367.5 MPa. The plastic strain ratio[r]was 2.45 and the strain hardening index[n]was 0.28. The volume fraction of {111} plane texture was 65%. There are a small quantity of nano-size precipitates of TiC and bigger MnS and Ti4C2S2. The dislocation density increased when the strain increasing from 0.5% to 11% and the dislocation structure was dislocation lines，cellular dislocation and trapezoidal dislocation.
		2018 Vol. 53 (2): 55-59 [Abstract] ( 360 ) [HTML 1KB] [PDF 1303KB] ( 1043 )

	60	ZHANG Kai-qiang，，LI Ji-guang，ZHAO Ji-qing，TANG Guang-bo
		Effect of long term aging on microstructure and mechanical properties of ЭП866 steel
		Effect of aging at 650 ℃ for up to 2 000 h on microstructure and mechanical properties of ЭП866 steel was investigated，and Thermo-Calc software was used to study the effect of Cr content on the equilibrium precipitation behavior of σ phase. The results showed that after long-term aging at 650 ℃，precipitation phases in the steel consist of M23C6 、MX、Laves and σ phase. In addition，martensitic lath recovery and the coarsening behavior of precipitates also occurred. The sharp decrease of hardness and strength after aging for 500 h could be attributed to the combined effects of the coarsening of precipitates and the recovery of microstructure. However， these two properties decreased slowly with longer aging time，due to the large number of precipitation of σ phase，which was characterized as a hard and brittle phase. The impact energy decreased during aging for 1 000 h，resulting from the coarsened Laves phase and M23C6 particles distributed in chain-shape. Additionally，the softening effect by microstructure recovery brought about higher impact energy after longer aging time. Results from Thermo-Calc calculations show that the precipitation of the σ phase in this steel is related to segregation of Cr in the vicinity of grain boundaries during aging.
		2018 Vol. 53 (2): 60-66 [Abstract] ( 353 ) [HTML 1KB] [PDF 2028KB] ( 1003 )

	67	WANG Bo，LI Zhu-tie，Isayev Oleg，WU Kai-ming，ZHAN Dong-ping
		Development of low temperature pressure vessel steel by Zr-Ti combined deoxidization technology
		In order to investigate the effect of Zr-Ti oxides on the mechanical properties of steel， the low temperature pressure vessel steel was manufactured by Zr-Ti combined deoxidization technology replacing Al deoxidization in the process of LD-LF/RH-CC-TMCP-QT. Metallographic microscope， SEM， EDS and mechanical property tests were carried out. The results showed that the fine Zr-Ti compound oxide-sulfide inclusions were formed. The microstructure consisted of predominantly bainite and lots of acicular ferrite， which was homogeneous and fine，with the grain size being more than grade 9. The investigated steel had superior mechanical properties especially the low temperature impact toughness. Its mechanical properties were almost isotropic in transverse and longitudinal directions. The impact absorbed energy reached above 100 J at the temperature of -60 ℃and the DBTT （ductile brittle transition temperature） was lower than -55 ℃. Thus the Zr-Ti combined deoxidization technology had the effect of grain refinement and microstructure homogenization on the steel.
		2018 Vol. 53 (2): 67-72 [Abstract] ( 410 ) [HTML 1KB] [PDF 1193KB] ( 755 )

	73	SUN Zheng-han，， HUANG Xiao-li，DING Yue-hua，GENG Zhao-yang，，GAO Jian-yong，，LIN Yin-he
		Effect of B2O3 on separation of perovskite and slag inTi-bearing blast furnace slag
		In order to study the slag composition of vanadium-titanium magnetite in the blast furnace smelting process and slag-iron slag， the slag composition was adjusted by adding different proportions of B2O3 modifiers. The effects of modifier on the microstructure and the precipitation behavior of the titanium ore grains were investigated， and the modification mechanism of the additive B2O3 was discussed preliminarily. The results show that the addition of a certain amount of B2O3 can inhibit the precipitation of perovskite grains obviously， and the effect increases with the B2O3 content increasing. The product is analyzed by SEM-EDS， and it is found that the metal iron grows more easily with the increase of the amount of B2O3 modifier. As a low melting flux into the high titanium blast furnace slag， B2O3 can effectively reduce the viscosity of metallurgical slag and liquidus temperature， and change the phase composition of slag to achieve a better enrichment of titanium-rich. Thus， the mechanism inveatigation can provide a theoretical basis for the future utilization of high titanium blast furnace slag.
		2018 Vol. 53 (2): 73-77 [Abstract] ( 392 ) [HTML 1KB] [PDF 1517KB] ( 975 )

	78	LIU Song，Lü Qing，ZHANG Xu-sheng，LIU Xiao-jie，WANG Shu-huan，LI Fu-min
		Change rule of top gas circulation in blast furnace gas injection process
		The new technology of blast furnace coal injection combines traditional technology of blast furnace with gas-making furnace and achieves a rational use of top gas through top gas recycling. The results show that with the increase of the cycle time，the amount of coal required increases，the content of H2 and CO in the gas-making furnace increases，and the total heat input and heat budget of blast furnace decrease. With the volume fraction of H2 and CO in the top gas increasing，the volume fraction of N2 and CO2 decreasing and the circulation of gas，the gas composition is basically unchanged，and the optimum running state of the blast furnace is guaranteed.
		2018 Vol. 53 (2): 78-82 [Abstract] ( 404 ) [HTML 1KB] [PDF 785KB] ( 1164 )

	83	LI Xiao-ming，YIN Wei-dong，SHEN Miao，ZOU Chong，CUI Ya-ru，ZHAO Jun-xue
		Desulfurization dynamics on reduction pre-treatment of sludge from pickling of chromium nickel stainless steel
		Pickling sludge generated during the neutralization of pickling waste water with calcium hydroxide contains valuable resource，such as Ni，Cr and Fe，which can be returned to the smelting process to realize the target of sludge detoxification，consumption and resource utilization. The key of pickling sludge returning to steelmaking is the stability of sulphate in slag，conversion and prevention resulfurization of molten steel. Aiming at the problem above，reduction pre-treatment of chromium nickel stainless steel pickling sludge was proposed，and desulfurization kinetics on reduction process of stainless steel pickling sludge was analyzed using differential thermal thermogravimetric method. The results show that at the temperature of desulfurization reaction 800-1 000 ℃，low heating rate 10 ℃/min is well for sulfur removal in the sludge. The most probable mechanism function of pickling sludge desulfurization process is Avrami-Erofeev formula， the mechanism is consistent with random nucleation and subsequent growth models，and the apparent activation energy of the thermal decomposition reaction is obtained as 492.909 7 kJ/mol.
		2018 Vol. 53 (2): 83-90 [Abstract] ( 328 ) [HTML 1KB] [PDF 1689KB] ( 840 )

	91	LIU Yan，，CAO Jian-ning，，GENG Ming-shan，
		Research and development of water-cooled casting technology for over-thick ingot blanks of offshore platform rack plate
		In the current study，the standard and production status of rack steel for offshore platform at home and abroad were described from the view of manufacturing of extra-thick plate blanks，and the production technology and difficulties of the extra-thick plate blanks were analyzed. Based on this，the water-cooled mould casting technology with sequential solidification and the result of pilot test were introduced，and the feasibility of casting plate blanks of rack steel with water-cooled mould casting technology was predicted by simulation. The simulation results show that the rack steel plate blanks of large piece weight and high quality can be generated by water-cooled mould casting technology with sequential solidification，which explores a economical and practical process for producing rack steel plate blanks.
		2018 Vol. 53 (2): 91-96 [Abstract] ( 333 ) [HTML 1KB] [PDF 1200KB] ( 1003 )

	97	SHI Xin-yue，HAN Wei-gang，LI Xiu-ping，ZHANG Chun-xia，WU Chong-yuan，WEI Zhi-jun
		“One Ladle Technology” operation practice analysis in Shougang Jingtang
		“One Ladle Technology” mode is more advanced operation mode in BF-BOF section. OLT，which has a significant advantage in area occupying，equipment investment，staffing and operation time，temperature drop of hot metal and dust emission compared with other models，has been gradually accepted and applied in steel production enterprises. Based on the case study of BF and BOF section “One Ladle Technology” in Shougang Jingtang，operation mode in time and HML turnover time，temperature drop of full HML and empty HML are analyzed. Based on the results，the dynamic operating rules for HML turnover are put forward which has achieved remarkable results in Shougang Jingtang.
		2018 Vol. 53 (2): 97-102 [Abstract] ( 416 ) [HTML 1KB] [PDF 1086KB] ( 840 )

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