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	2017 Vol. 52 No. 5
	Published: 2017-05-15

	1	LI Xin-chuang
		Respond challenges positively to promote healthy development of international steel trade
		In the current article，the issues of development and transfer of the world steel industry，new normal and outlook of Chinese steel industry，international steel trade and Chinese steel import and export etc are discussed. As the biggest steel exporter in the world，Chinese steel is confronted with varied trade protection measures although it is satisfying demand of overseas users. In this article some ideas on how to evaluate the export of Chinese steel objectively are provided，and how to respond the trade protection measures against Chinese steel as well as strategies adopted for Chinese steel import and export over the coming years are analyzed comprehensively.
		2017 Vol. 52 (5): 1-4 [Abstract] ( 538 ) [HTML 0KB] [PDF 0KB] ( 59 )

	5	LU Hua，WU Sheng-li，ZHANG Jian-liang，CHANG Feng，LI Hong
		Forming dynamics of pellet made frozinc-bearing dust in steel plant
		Large amount of iron-bearing dust could be generated in the steel production process. At present，the best way of effective utilization of iron-bearing dust in China is pelletizing using the dust and to producemetallized pellet using the rotary hearth furnace. The basic characteristics of iron-bearing dust，including sintering，blast furnace and electric furnace dust，are investigated through the chemical analysis，laser particle size，BET specific surface area and X-ray diffraction. Furthermore，the pelletizing experiment ofthree kinds of dust is carried out，and the optimal pelletizing parameters are investigated based on the balling dynamics and the green pellet strength. The results show that the dust from sintering has good forming dynamics，while its green pellet strength can not meet the requirement under the current experimental condition. The dust from electric furnace has a relative large adhension，hence，tends to stick on the wall. The dust from blast furnace has not only a good forming dynamics，but has a large green pellet strengh. To ensure the yield and quality of the pellet，the appropriate pelletizing parameters of BFD are 12.5%～13.0%moisture，2% bentonite，20 min pelletizing time，27～31 r/min rotating speed and 5 kg feeding amount.
		2017 Vol. 52 (5): 5-12 [Abstract] ( 590 ) [HTML 0KB] [PDF 0KB] ( 54 )

	13	ZHOU Jian-an，DING Bin，DENG Dong-yi，JIANG Xue-kai，XIE Jian-bo
		Action and behavior of gelatinized starch in iron pellets
		In order to investigate the action and behavior of gelatinized starch in iron pellets，the baking trials of pellets were conducted based on the gelatinized starch and magnetite concentrate. The characteristics of the gelatinized starch and the effect of the gelatinized starch on the inner structure of pellets materials were investigated using the approaches of FT-IR，TG，SEM and XRD. The results showed that the gelatinized starch had much more polar group than that of ordinary starch，which could help to improve the strength of pellets and the adhesion of iron ore due to the mutual actions of polar groups and ions of iron ore surfaces. When the mass percent of the gelatinized starch into the pellets is 2%，the drop strength of raw pellets was 11.2/0.5 m，and the compressive strength reached 17.5 N/one pellet. The gas produced by the reaction of the gelatinized starch and oxygen escaped from the inner structure during the baking，which was beneficial to increase the gas-pore amount within pellets and further facilitate the oxidation of Fe3O4，hence，the iron grade of pellets was improved.
		2017 Vol. 52 (5): 13-18 [Abstract] ( 647 ) [HTML 0KB] [PDF 0KB] ( 64 )

	19	LI Ya-qiang，AI Li-qun，LI Qiang，CHENG Rong，CHEN Peng-fei，LIU Xin-liang
		Experiment of gas-solid decarburization process of 1 mm Fe-C alloy ribbon
		Focus on the study of decarburization behavior of 1 mm iron-carbon alloy ribbons with carbon mass content of 4.2%，a series of gas-solid reaction experiments at different temperatures were carried out. The impact of different temperatures on the decarburization of Fe-C ribbons and the dynamics of decarburizing process were investigated with the atmosphere of Ar-H2-H2O mixed gas，the gas flow rate was set as 400 mL/min，and the ratio of[PH2O/PH2]was 0.85. The results showed that rising decarburizing temperature can improve the decarburization rate effectively. For example，the carbon content decreased to 0.12% after 30 min decarburization at 1 413 K. Apparent decarburizing process can be concluded as nearly first-order reaction. Apparent activation energy of the decarburizing process calculated is 157.9 kJ/mol. The surface gas-solid chemical reaction is the controlling step in initial decarburizing stage and then，the diffusion of carbon in ribbon bulk is the main controlling step in the following process.
		2017 Vol. 52 (5): 19-23 [Abstract] ( 497 ) [HTML 0KB] [PDF 0KB] ( 64 )

	24	WANG Guo-cheng，ZHOU Hai-chen，LIU Fa-you，WANG Qi
		Numerical simulation of bubble formation and motion process in ladle refining
		This paper mainly does the following researches with the object of argon bubble in the process of the blowing argon from the bottom of ladle. The VOF numerical simulation was used to track the interface of argon gas and the liquid steel. Three-dimensional numerical simulation method is used to simulate the bubble generation and movement under laminar condition. Using the Tecplot to analyze the post-processing of simulation results， the influence of different gas flow conditions on the bubble diameter and movement characters was investigated. Simulation results show that the bubble formation consists of two stages，that are expansion and detachment. The departure diameter of bubble increases with the increase of the gas flow rate. The upper limit of the bubbling regime is 1.325 L/min for nozzle with 2 mm diameter. The bubble shape is changed with approximate spherical，flat elliptical spherical，regular spherical and irregular spherical cap. The deformational degree of bubble increases with increasing the gas flow rate. All of bubbles present approximate spherical when located in the upper position of ladle height and do not change with the flow rate.
		2017 Vol. 52 (5): 24-30 [Abstract] ( 726 ) [HTML 0KB] [PDF 0KB] ( 73 )

	31	ZHAI Jun，，LIU Liu
		Investigations on inclusion control of heat resistant steel 310S in EAF＋AOD＋LF process
		For achieving preferable corrosion resistance，the cleanliness of 310S stainless steel needs to be improved further. The cleanliness of 310S heat resistant steel produced by EAF＋AOD＋LF process were studied by means of chemical analysis，metallographic observation as well as scanning electron microscope. Based on the results，the optimizing solutions were put forward. The results indicated that increasing AOD slag basicity to 2.0，adding Al in LF process to deep deoxidizing and prolonging the Ar blowing time to remove inclusions with large size were very effective. After optimizing，[w(T[O])] in steel slab decresed from 0.003 4%to 0.002 5%，and the amount of inclusions with the size of 1-7 μm increased by 15.5%，the amount of inclusions larger than 15 μm decreased by 5.8%，and large inclusions over 30 μm were approximately eliminated.
		2017 Vol. 52 (5): 31-35 [Abstract] ( 617 ) [HTML 0KB] [PDF 0KB] ( 68 )

	36	DONG Wen-liang，LUO Lei，TIAN Zhi-hong，JI Chen-xi，LIU Yan-qiang，PAN Hong-wei
		Recycle of decarburization-slag in dephosphorization-furnace of duplex process in converter
		During duplex process in converter，the decarburization-slag with low[w((P2O5))]was added into dephosphorization-furnace through slag-vessel to realize the recycle of slag. The amount of recycle slagand the phosphorus distribution would greatly affect the addition amount of lime in dephosphorization-furnace，the target phosphorus content could be achieved without adding any lime in dephosphorization-furnace if the recycle slag amount and the phosphorus distribution were controlled properly. The dissolution of decarburization-slag in dephosphorization-furnace was calculated and analyzed. As the Si in hot metal was oxidized，the melting point of slag was lowered with the decrease of slag basicity in the blowing process. The recycle slag process was developed in the plant trials，the lime was saved by 9.37 kg/t，the light-burned dolomite was saved by 1.15 kg/t，the fluorite was saved by 2.45 kg/t，and the temperature increased by approximately 7 ℃ when the recycle slag amount increased to 67.13 kg/t. The dephosphorization rate increased by approximately6%.
		2017 Vol. 52 (5): 36-42 [Abstract] ( 641 ) [HTML 0KB] [PDF 0KB] ( 55 )

	43	LONG Xiao，HE Sheng-ping，WANG Qian
		Experiment on solidification and composition segregation of solidified mold flux film for peritectic steel continuous casting
		The structure and property of mold flux films are critical factors for enhancing the quality of casting products and maintaining a stable running of casting. An improved water-cooled copper probe was adopted to obtain solid slag films with different probe immersion times. Optical microscopes and SEM were used to inspect the internal structure of films，SEM-EDX was adopted to measure the composition segregation within the film for deducing the composition change of liquid slag at solidification front. The result reveals that the major crystal forms in solid films are cuspidine and carnegieite，the precipitation of cuspidine changes the composition of liquid slag at the solidification front and promotes the precipitation of carnegieite，which leads to the rapid growing of solid slag film.
		2017 Vol. 52 (5): 43-46 [Abstract] ( 608 ) [HTML 0KB] [PDF 0KB] ( 45 )

	47	LI Nong，LI Hong-bo，ZHANG Jie，JIA Sheng-hui，CHU Yu-gang，LIU Hai-jun
		Post buckling analysis of cold rolled strip based on incompatible F?ppl-von Kármán equations
		In order to reveal the relationship between pre-buckling residual stress and post buckling deflection，post buckling residual stress of cold rolled strip，the incompatible F?ppl-von Kármán equations is introduced to establish the model of boundary value problem of nonlinear partial differential equations of infinite strip with two free boundaries. The boundary value problem of nonlinear partial differential equations is simplified to a boundary value problem of nonlinear ordinary differential equations with consideration of harmonic pattern of deflection. After non-dimensionalization of the involved quantities，the non-dimensional deflection with undetermined coefficients are determined by analyzing the magnitude of quantities. The total potential energy can be written only by using non-dimensional deflection and the undetermined coefficients are calculated by using Ritz method. The calculated deflection agrees well with results mentioned in other literature，and the deviation is explained. Aiming at a typical product of a cold rolling mill，the post buckling released residual stress is calculated and the minimum tension is determined，which provides a reference to application of flatness measurement.
		2017 Vol. 52 (5): 47-54 [Abstract] ( 589 ) [HTML 0KB] [PDF 0KB] ( 74 )

	55	HU Sheng-de，CHENG Xue-peng，LI Li-xin，DING Fan，PAN Cheng-gang
		Analysis of cold-formed residual stress considering coiling-flattening process
		From two aspects that considering the strain hardening （bilinear kinematic hardening） and without considering the strain hardening（elastic-perfectly plastic body），to the current study analyzed the stress that were produced in coiling，uncoiling，flattening，bending and rebounding processes，and obtained the residual stress distribution along the thickness direction during the coiling-rebounding. The effect of considering the strain hardening and without considering the hardening on the residual stress distribution of cold bending is researched. The calculated results are compared with the measured residual stress. The results show that residual stress distributions that were predicted by the two prediction models is almost the same. As the yield occurred on coil，the longitudinal residual stress distribution was nonlinear along the thickness direction（when the yield did not occur on coil，the stress distribution was linear），and the horizontal residual stress distribution was linear. The residual stress was mainly tensile stress from outer surface to neutral layer（horizontal residual stress had a very small compression area at the outside of deformation zone），and it was the compressive stress from inner surface to neutral layer（horizontal residual stress had a very small tension area at the inside of deformation zone）. Both horizontal residual stress and longitudinal residual stress had the maximum value on the neutral layer. The calculated results agreed with the experimental results.
		2017 Vol. 52 (5): 55-60 [Abstract] ( 557 ) [HTML 0KB] [PDF 0KB] ( 74 )

	61	QIU Zeng-shuai，HE An-rui，SHAO Jian
		Numerical simulation of transverse bending of hot rolled medium carbon steel strip
		Several finite element models during the cooling process of hot rolled strip on the ROT are established to research transverse bending defects with the software ABAQUS combined with language of FORTRAN. The influence of the uneven cooling of the upper and lower surfaces and the strip thickness on the strip transverse bending is analyzed according to the models. The results show that the transverse bending will be more obvious as the difference of cooling efficiency of the two surfaces is larger. Besides，if the difference of cooling efficiency on the two surfaces is invariable，strip transverse bending will be more serious as the strip being thicker. During cooling process，the bending direction and size of strip will change a lot under the influence of temperature change and phase transformation. The maximum bending value of the strip in the cooling process is much larger than the bending value after cooling.
		2017 Vol. 52 (5): 61-65 [Abstract] ( 589 ) [HTML 0KB] [PDF 0KB] ( 58 )

	66	LEI Dong，REN Yong，CHENG Xiao-ru，LAN Kun，QIU Jun，HUANG Da-jun
		Effect of heat treatment on microstructure and mechanical properties of 316L/Q235 stainless steel composite panel
		The microstructure and mechanical properties of hot rolled stainless steel composite panel was studiedin viewofheat treatment.The microstructure was observed and composition was analyzed by scanning electron microscopy （SEM）. The hardness of samples was measured by Vickers. The mechanical properties were studied by shear and tensile test. The results show that vacuum hot rolling canobtain good composite board. The organization in carbon steel side is ferrite and pearlite，and the organizationin stainless steel side is single austenite. After the heat treatment，the performance of interface combination improves and the shear strength，yield strength and tensile strength increased accordingly. The heat treatment systemthat is fast cooling at high temperature andslow cooling at low temperature is suitable for 316L/Q235 stainless steel composite plate.
		2017 Vol. 52 (5): 66-71 [Abstract] ( 624 ) [HTML 0KB] [PDF 0KB] ( 61 )

	72	LIU Bao-long，，ZHANG Hui-fang，XIAO Zhen-xing，[LU]Zhi-qing，FU Wan-tang，REN Ting-zhi
		Microstructure evolution and properties of interface in 316L/Q345R hot rolled clad plate
		The interface microstructure and element diffusion of 316L/Q345R hot rolled clad plate were investigated using SEM （scanning electron microscopy） and EDS （energy diffraction spectrum）. The distribution of carbon content near the interface was also analyzed through the thermodynamic calculation，and the micro hardness and shear strength of the interface were measured. There exists about 50 μm ferrite band on the carbon steel side and about 100 μm influence zone from element diffusionon the stainless steel side near the interface.Cr，Ni and other elements in the stainless steel spread to the carbon steel，and C element in the carbon steel diffuses to the stainless steel. The interfacial shear strength of the cladplate is 373 MPa，which is significantly higher than that of the standard 210 MPa，nevertheless slightly lower than half of the sum of shear strength of Q345R and 316L（379 MPa）.
		2017 Vol. 52 (5): 72-76 [Abstract] ( 623 ) [HTML 0KB] [PDF 0KB] ( 66 )

	77	LI Xin-yu，，YANG Mao-sheng，ZHOU Xiao-long，WANG Bo，
		Influence of Co and Mo on microstructure and mechanical properties of bearing steel with high content of cobalt，chromium and molybdenum
		The influence of Co and Mo on the microstructure and mechanical properties of bearing steel with high content of cobalt，chromium and molybdenum wereinvestigated by the testof performance and the observationof microstructure. Main results showthat the reduction of Co and Mo contents and the change of Co to Mo ratio could cause the decrease of comprehensive mechanical properties of test steels. The hardening and tempering microstructure of test steels were lath martensite and retained austenite，the difference between Creq and Nieq became larger under the influence of Co and Mo elements，which reduced the content of retained austenite and produced δ-ferrite. Moreover，the carbides changed from the 1.17% granulated M6C to the 0.15% acicular M2C. The strength of test steels was mainly affected by carbides，when the contents of carbides was less than 0.15%，With the decrease of [w(Co)/w(Mo)，]the dislocation density increased，and the strength of test steels increased. The toughness of test steels was mainly affected by δ-ferrite. If the content of δ-ferrite was more than 6.3%，the test steel would become brittle，if the contentwas less than 1.1%，the toughness of test steels would be excellent.
		2017 Vol. 52 (5): 77-86 [Abstract] ( 597 ) [HTML 0KB] [PDF 0KB] ( 85 )

	87	QING Jia-sheng，SHEN Hou-fa，LIU Ming
		V-N microalloying of high strength weathering steel YQ450NQR1
		V-N microalloying is a main method to improve the yield strength of weathering steel YQ450NQR1. The performance of high strength weathering steel YQ450NQR1 microalloyed with vanadium and nitrogen is mainly influenced from vanadium and nitrogen，i.e.，the vanadium mainly plays a part of the grain refinement and precipitation strengthening，and the main function of nitrogen is to strengthen the role of vanadium. Through the research of the product of vanadium and?nitrogen[w(V)·w(N)]in high strength weathering steel YQ450NQR1，it is found that with the increase of vanadium content and nitrogen content，the yield strength of the steel is improved，and the yield strength is influenced by the product of vanadium and nitrogen[w(V)·w(N).] In order to guarantee the yield strength of weathering steel YQ450NQR1 up to 465 MPa，the product of vanadium and nitrogen[w(V)·w(N)]should be over 0.001 44. In order to improve the ductility of the continuous casting slab at high temperature and reduce the cracking sensitivity of the cast slab，the nitrogen should be controlled in the range of 0.012%-0.014%.
		2017 Vol. 52 (5): 87-93 [Abstract] ( 571 ) [HTML 0KB] [PDF 0KB] ( 53 )

	94	SHEN Kang，XU Le，SHI Jie，HE Xiao-fei，WANG Mao-qiu
		A new torsion bar spring steel with ultra-high strength and low hydrogen embrittlement sensitivity
		Microstructure and mechanical properties of newly developed 40Si2Ni2CrMoV steel （code name N1） and the existing 45CrNiMoVA steel were investigated by scamning electron microsope (SEM)，transmission electron microscope (TEM)，X-rany diffraction (XRD) and chemical phase analysis，and hydrogen embrittlement of these two steels was also investigated by slow strain rate tensile. The results show that N1 steel can keep high strength at higher temper temperature of 300 ℃ due to the addition with silicon and molybdenum element，which improve resistance to tempering softening. The fine ε-carbide in N1 steel can improve the yield strength，which keeps the yield ratio above 0.8，while the yield strength of 45CrNiMoVA steel is 1 550 MPa at the lower temper temperature of 180 ℃，and the yield ratio is only 0.72. The hydrogen embrittlement of N1 steel significantly lower than of 45CrNiMoVA steel，which is shown in the following aspects： the slow strain rate tensile strength of N1 steel decreases slightly compared with 45CrNiMoVA steel，and there is no intergranular fracture feature observed in tensile sample fracture.
		2017 Vol. 52 (5): 94-99 [Abstract] ( 600 ) [HTML 0KB] [PDF 0KB] ( 83 )

	100	ZHANG Hong-liang，，SHI Qi，LONG Hong-ming，，LI Jia-xin，CHUN Tie-jun，GAO Zhi-fang
		Analysis of [NOx]removal process in sintering flue gas
		With the government’s increasingly stringent emissions requirements of pollutants，the[NOx]removal from sintering flue gas becomes an important direction of pollution control in the steel industry. At present，[NOx]removal in sintering process is mainly achieved by the control of raw material and process，while the terminal control technology which is the key of denitration in the future is not mature. Therefore，this paper simply introduces the technology of raw material control and process control，and the problems and solutions of terminal control technology，especially selective catalytic reduction technology in sintering flue gas treatment are mainly introduced.
		2017 Vol. 52 (5): 100-106 [Abstract] ( 645 ) [HTML 0KB] [PDF 0KB] ( 65 )

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