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Preparation of TiC Reinforced Iron Based Composite Powder by Electrochemical Reduction from High Titanium Slag with Carbon

Sun Lin, Jiang Yan, Yu Yanmin, Ji Chunwei, Song Qiushi

2019, 40(6): 1-5. doi: 10.7513/j.issn.1004-7638.2019.06.001

Abstract(241) PDF(8)

Abstract:
Titanium carbide（TiC） reinforced iron（Fe） based composite powder with a multi-core structure was electrochemically prepared directly from high titanium slag and carbon powder.The electrochemical reaction pathways for the sintered piece of the slag and carbon were investigated by examination of the partially and fully reduced samples using XRD and SEM-EDS analyses.The reduction process of the sintered piece of high titanium slag and carbon can be divided into two main stages.The first stage is the electrochemical reduction of the high titanium slag,leading to the formation of Fe,titanium monoxide（TiO） and calcium titanate（CaTiO₃）.The second stage is a transformation process of TiO→TiC_xO_1-x→TiC.The ratio of high titanium slag to carbon powder affects the final composition of the products,and the increase in carbon powder addition can increase the TiC content of the final products.

Optimization for Recovery Process of Low-grade Olivine-type Ilmenite

Wu Xuehong

2019, 40(6): 6-11. doi: 10.7513/j.issn.1004-7638.2019.06.002

Abstract(186) PDF(4)

Abstract:
Aiming to resolve the problems of high cost and low yield for industrial recovery of low-grade olivine-type ilmenite in a mining company in Panzhihua-Xichang area,the process optimization was carried out.By improving the screw feeder and the second-stage high-intensity magnetic operation section in the factory,the TiO₂ grade in the flotation material can be effectively increased and the cost of flotation agents can be effectually decreased,with the rate of titanium concentrate increased by 14.18%.The optimization can realize the recovery of the low-grade olivine-type ilmenite with higher efficiency and lower cost.

Preparation and Photocatalytic Performance of Graphene/Fe-doped Titania Composite

Yang Ying

2019, 40(6): 12-17. doi: 10.7513/j.issn.1004-7638.2019.06.003

Abstract(272) PDF(3)

Abstract:
Graphene/Fe-doped titania composite was prepared by one-step thermal hydrolysis of industrial titanyl sulfate solution with graphene oxide solution as priming,and the composite was characterized using XRD,SEM,FT-IR,UV-vis DRS and XPS.The photocatalytic performance of the graphene/Fe-doped titania composite was evaluated by the photooxidation of methylene blue under UV light and visible light irradiation,respectively.The effects of graphene oxide solution concentration,feeding rate and heating rate on the photocatalytic activity of the graphene/Fe-doped titania composite were systematically investigated.The results indicate that the doping-Fe enters TiO₂ lattice in the form of Fe³⁺ to form impurity energy level and extend the spectral response range to visible light of the composite consequently.Graphene is beneficial to separate the photoexcited electron-hole pair and then to improve the quantum efficiency of photocatalysis.The optimal hydrolysis conditions are graphene oxide solution concentration of 0.03 mg/mL,feeding rate of 8 mL/min and heating rate of 1.0 ℃/min.The photocatalytic efficiency of the composite obtained at these conditions can reach 94.15% and 80.89% respectively under UV light and visible light irradiation.

Technical Discussion on Improving AlV55 Yield

Chen Haijun, Shi Qihua, Wang Yonggang, Yin Danfeng, Ye Mingfeng

2019, 40(6): 18-23. doi: 10.7513/j.issn.1004-7638.2019.06.004

Abstract(256) PDF(8)

Abstract:
In this paper,the factors affecting the yield of AlV55 alloy prepared by aluminum thermal reduction method were studied,and the approaches for improving the yield were also discussed.The influencing factors include fine powder,oxides film and segregation,etc.With the unit heat effect at 3 315 kJ/kg,the alloy has a good apparent quality and the yield can be effectively improved.The effect of the brittle phase Al8 V5 on the fine powder rate and oxides film can be minimized by increasing the vanadium content of the alloy within the standard range.By cross-rotating the furnace body,the alloy liquid can be self-stirred to achieve uniform alloy compositions and reduce the composition segregation.

Influence of Mixing-milling Technique on Sodium Roasting of Vanadium Slag

Jiang Lin, Wu Zhenxiu, Gao Guanjin

2019, 40(6): 24-29. doi: 10.7513/j.issn.1004-7638.2019.06.005

Abstract(257) PDF(5)

Abstract:
Vanadium slag and sodium carbonate were mixed and milled by an omni-directional ball mill.The particle size distribution,morphology and uniformity of the materials after mixing and milling were analyzed and compared with those of the materials of vanadium slag and sodium carbonate by direct mixing.The difference in leaching rate of the roasted vanadium slag respectively by the direct mixing and mixing-milling processes were investigated at variable alkali ratios,and the effects of mixing-milling time and roasting temperature on the leaching rate of the roasted vanadium slag were also studied.The results show that compared with direct mixing the mixing-milling process can increase the leaching rate of the roasted vanadium slag significantly at the same alkali ratio.A leaching rate of 92.67% can be obtained for the roasted vanadium slag by mixing-milling process at 22% of alkali ratio,while the leaching rate of 92.34% can be obtained for the roasted vanadium slag by direct mixing at 26% of alkali ratio.The mixing-milling process can decrease the sodium carbonate dosage at the same leaching rate requirement in comparison with the direct mixing.When the mixing-milling time exceeds 20 min,the leaching rate of the roasted vanadium slag changes slightly.The favorable roasting temperature is determined at 770～790 ℃.The research has a practical guidance on enhancement of vanadium recovery and decrease of sodium salt consumption during sodium roasting of vanadium slag.

Effect of Titanium Liquid Index on Hydrolysis Rate

Wu Jianchun, Lu Ruifang

2019, 40(6): 30-33. doi: 10.7513/j.issn.1004-7638.2019.06.006

Abstract(348) PDF(18)

Abstract:
Using the industrial titanium liquid as the raw material,the hydrolysis was carried out by external seeding.The effects of titanium liquid index including TiO₂ concentration,F value,Fe/TiO₂ ratio and Ti³⁺ concentration on the hydrolysis rate were investigated.Then,the relationship between the hydrolysis rate and the index of titanium liquid was deduced by hydrolysis equilibrium theory.The results show that with the increase of TiO₂ concentration,the hydrolysis rate decreases.With the increase of F value,the hydrolysis rate decreases sharply.With the increase of Fe/TiO₂,the hydrolysis rate also decreases.With the increase of Ti³⁺ concentration,the hydrolysis rate is on a downward trend.The theoretical derivation results show that at the same dilution ratio,the hydrolysis rate at the equilibrium is linear with the product of the total titanium concentration and the square F value,and the intercept is related to the concentration of Ti³⁺.

Effects of Nickel Element on Microstructure and Properties of VC Reinforced Iron-base Composite

Xian Yong, Ding Yichao, Chen Deping, Wang Jing, Wang Huai

2019, 40(6): 34-37. doi: 10.7513/j.issn.1004-7638.2019.06.007

Abstract(223) PDF(3)

Abstract:
VC reinforced iron matrix composites were synthesized in situ from FeV powder,Ni powder and graphite powder under sintering temperature of 1 150 ℃ and pressure of 20 MPa.X-ray diffraction（XRD） was used to analyze the phases.Three-point bending strength and Rockwell hardness were tested,and scanning electron microscopy（SEM） was used to analyze the microstructure and fracture morphology.The results show that,due to the stabilization of austenite by Ni,dual phases of α-Fe and γ-Fe appear in the iron matrix when the content of Ni exceeds 6%,with its microstructure of pearlite and austenite.The hardness and bending strength of the specimens increase with the increase of Ni content.When Ni content increases to 9%,the hardness increases from 39 HRC to 43.7 HRC.The bending strength increases from 1 028 MPa to 1 926 MPa,and the fracture mode changes from cleavage fracture to dimple fracture.

Investigation on the Structures and Electrochemical Properties of V₂Ti_0.5Cr_0.5Ni_1-xMn_x（x=0.05～0.2）Hydrogen Storage Alloys

Tong Yanwei, Li Nali, Cui Xumei, Zhang Xuefeng

2019, 40(6): 38-42. doi: 10.7513/j.issn.1004-7638.2019.06.008

Abstract(222) PDF(4)

Abstract:
V₂Ti_0.5Cr_0.5Ni_1-xMn_x（x=0.05～0.2）hydrogen storage alloys were prepared by vacuum induction arc-melting,and the microstructure and electrochemical properties of the alloys were investigated systematically.The results show that the alloys mainly consist of a V-based solid solution phase with a BCC structure and a TiNi-based secondary phase.The electrochemical tests indicate that with increase of Mn content in the alloys,the high-rate discharge capability,maximum discharge capacity and exchange current density of the alloys increase gradually.The maximum discharge capacity of 429.3 mAh/g,high-rate discharge capability of 55% and exchange current density of 52 mA/g can be obtained for the alloy at x=0.2,with the electrochemical kinetics improved but the cycling stability weakened.

Effect of TiO₂ on Hydrogen Evolution Performance of Sn-Ni Alloy Electrode

Zhou Zongyi, Wen Linjie, Zhang Linan, Qi Haidong, Li Yungang, Yang Haili

2019, 40(6): 43-47. doi: 10.7513/j.issn.1004-7638.2019.06.009

Abstract(219) PDF(3)

Abstract:
The Sn-Ni/TiO₂ composite electrode was prepared on the surface of pure copper by electrodeposition method.The morphology,composition,roughness and hydrogen evolution performance of the electrodes were studied by scanning electron microscopy,energy dispersive spectroscopy,laser scanning confocal microscope,cathodic polarization curve and electrochemical impedance spectroscopy.The results show that with the increase of TiO₂ concentration from 0 g/L to 1.0 g/L,the hydrogen evolution performances of the electrodes are improved firstly and then weakened.The Sn-Ni/TiO₂ electrode with the maximum TiO₂ content is obtained at the TiO₂ concentration of 0.8 g/L,and pollen-like agglomerate of TiO₂ is observed on the surface of the electrode which has the largest roughness and the best hydrogen evolution performance.

Microstructure and Mechanical Properties of Interface for Titanium/Steel Clad Tubesheet Prepared by Explosive Welding

Zhang Hangyong, Zang Wei, Guo Longchuang

2019, 40(6): 48-51. doi: 10.7513/j.issn.1004-7638.2019.06.010

Abstract(290) PDF(9)

Abstract:
Explosive welding tests of ø4600 mm ASME SB265 Gr.1/SA266 Gr.2 titanium/steel clad tubesheet were carried out,and the microstructure and mechanical properties of the clad tubesheet interface were analyzed and tested.The macro and micro analyses show that the bonding mode for interface of the clad tubesheet is wave-shaped,and the metals on both sides of the interface have undergone plastic deformation to different degrees.Near the interface,there exists short-distance mutual diffusion of elements.The interface has no defects such as layering and inclusion.Mechanical properties tests indicate that the Vickers hardness is the highest at the bonding interface,and it decreases with increasing the distance from the interface.The tensile,impact and bending properties of clad tubesheet meet the requirements of ASTM B 898 standard,which can meet the requirements of equipment using.

Structure and Properties of TiN Thin Film Deposited on Stainless Steel Surface by Sputtering

Luo Xueping, Lai Qi

2019, 40(6): 52-56. doi: 10.7513/j.issn.1004-7638.2019.06.011

Abstract(356) PDF(9)

Abstract:
The titanium nitride（TiN） thin film was prepared by direct current reactive magnetron sputtering on the surface of stainless steel.The rate of mass increase,microstructure,morphology and microhardness of the film were studied by analytical balance,SEM,XRD and microhardness tester.It is found that with the increase of sputtering time,both of the quality and thickness of the film are increased.XRD analysis shows that the TiN film has a face-centered cubic structure.The TiN film has a preferred orientation.With the increase of sputtering time,the preferred orientation changes from mixed crystal to（111）.The microhardness increases with the increase of sputtering time.

Preparation and Mechanical Properties of Porous Ti-5Nb Alloy with the Elongated Pores

Zhao Chaoyong, Kuang Lin, Zhang Xuefeng

2019, 40(6): 57-62. doi: 10.7513/j.issn.1004-7638.2019.06.012

Abstract(210) PDF(4)

Abstract:
Porous Ti-5 Nb alloys were prepared by powder metallurgy method using titanium and niobium powders as raw materials and spherical stearic acid as space holder,and the effects of stearic acid content on the microstructure and mechanical properties of porous Ti-5 Nb alloy were investigated by using the weighing method,XRD,SEM and universal mechanical testing machine.The results showed that porous Ti-5 Nb alloys with well-aligned and elongated pore structure were successfully prepared using spherical stearic acid as space holder.When stearic acid content increased from 10% to 50%,the phase composition of porous Ti-5 Nb alloy hardly changed,but its density decreased,the porosity increased,the connectivity between macropores increased,and elastic modulus and compressive strength decreased.The mechanical properties of porous Ti-5 Nb alloy can be matched with that of cortical bone and cancellous bone by controlling the amount of stearic acid.

Situation and Comprehensive Utilization Prospect of Titanium Gypsum

Fu Yijiang

2019, 40(6): 63-66,100. doi: 10.7513/j.issn.1004-7638.2019.06.013

Abstract(537) PDF(33)

Abstract:
Aiming at the problems of the large storage of titanium gypsum in China,which is the solid waste produced by titanium dioxide industry with an annual output of nearly 30 million tons,the shortcomings of the existing utilization ways were analyzed,and the directions and goals for large-scale comprehensive utilization of the titanium gypsum were put forward.It is considered that the surface water content of titanium gypsum should be not more than 20% after pressure filtration or calcination,and the II-type anhydrous gypsum（anhydrite） can be generated through secondary calcination.Furthermore,the II-type anhydrous gypsum can be used as clinker to produce super sulfate cement,transforming the solid waste into resource and realizing large-scale utilization of the titanium gypsum.

Study on Mechanical Properties of Flue Gas Desulphurization Gypsum-titanium Slag Powder Composite Cementitious Material

Yang He, Chen Wei, Liang Hezhi

2019, 40(6): 67-72. doi: 10.7513/j.issn.1004-7638.2019.06.014

Abstract(254) PDF(4)

Abstract:
Flue gas desulphurization gypsum-titanium slag powder（abbreviation:FGD-TS） composite cementitious material was prepared from flue gas desulphurization gypsum and titanium slag powder which are the industrial solid waste.The effect of addition amount of titanium slag powder on the phase composition and microstructure of FGD-TS composite cementitious material was investigated by XRD and SEM.The results show that with increase of the amount of titanium slag powder,the amount of dihydrate gypsum crystals per unit volume of FGD-TS composite cementitious material decreases,and both of the 2-hour bending strength and compressive strength of FGD-TS composite cementitious material decrease.The suitable amount of titanium slag powder is 10%～20%,and the titanium slag powder is embedded in the dihydrate gypsum crystals,which plays a role of skeleton and makes the dry compressive strength of FGD-TS composite cementitious material increased by 10%～27% with comparison with that of single flue gas desulphurization gypsum.It increases the long-term strength of FGD-TS composite cementitious material and meets the requirements of 3.0 grade of Building Gypsum（GB/T 9776—2008）.

Experimental Study on the Recovering Ilmenite from Iron Tailings in Panzhihua-Xichang Area by High Gradient Magnetic Separator with a Horizontal Magnetic System

Hu Houqin, Zhang Hongying

2019, 40(6): 73-76,128. doi: 10.7513/j.issn.1004-7638.2019.06.015

Abstract(171) PDF(6)

Abstract:
High gradient magnetic separation-high gradient magnetic separation-flotation process is adopted for ilmenite beneficiation in a plant in Panzhihua-Xichang area, and the high gradient magnetic separation stage is the key factor influencing the total recovery rate of ilmenite.Using the coarse material of iron tailings after concentrating and grading as raw materials, ilmenite was recovered by high gradient magnetic separator with a horizontal magnetic system and vertical magnetic system, respectively.The results show that under the optimal conditions, the high gradient magnetic separator with a horizontal magnetic system achieves the same recovery rate of titanium concentrate as the high gradient magnetic separator with a vertical magnetic system, but titanium concentrate with a higher TiO₂ grade can be obtained by the high gradient magnetic separator with a horizontal magnetic system.At the background magnetic field intensity of 430 mT, the titanium concentrate containing 16.21% of TiO₂ and 90.49% of titanium recovery can be obtained by one time of rough beneficiation of iron tailings.

Ultra-fine Electric Furnace Nickel Iron Slag Prepared by Steam Power Mill

Fu Haifeng, Li Tianhe, Qin Wenqian, Li Hong, Zhang Mingxing

2019, 40(6): 77-83. doi: 10.7513/j.issn.1004-7638.2019.06.016

Abstract(180) PDF(3)

Abstract:
The electric furnace nickel-iron slag emission is increasing,but the direct utilization rate is low.In order to improve the comprehensive utilization value of electric furnace nickel iron slag,ultra-fine pulverization experiments were carried out on a LNGS-80 steam power mill（total power 6.7 kW,steam consumption 80 kg/h）.The effects of the classifier speed on the particle size,specific surface area and output of the electric furnace nickel-iron slag were studied.The energy consumption and cost for milling the nickel-iron slag by the LNGS-10 T steam power mill（total power 165 kW,gas consumption 10 000 kg/h） were estimated.The results show that the ultra-fine powder commonly with d₅₀=12.9～52.7 μm,specific surface area of 305～669 m²/kg and yield of 167～480 kg/h,or the ultra-fine powder with d₅₀=2.4～4.7 μm,specific surface area of 1 788～2 669 m²/kg and yield of 35～80 kg/h can be prepared by pulverization and classfication of electric furnace nickel-iron slag using LNGS-80 steam power mill.It is estimated that LNGS-10 T steam power mill can prepare fine powder of electric furnace nickel-iron slag with d₅₀=28.5 μm and specific surface area of 464 m²/kg,and the system power consumption is 5.2 kWh/t which saves 89% of power consumption and 11% of cost compared with the roller mill.

Effects of Quicklime Digestion Behavior on the Granulation of Vanadium Titano-magnetite Concentrate

Liu Donghui, Li Junhua, Zhang Jianliang, Wang Guangwei, Peng Yue, Jiang Xi

2019, 40(6): 84-89. doi: 10.7513/j.issn.1004-7638.2019.06.017

Abstract(174) PDF(4)

Abstract:
Effects of quicklime digestion behavior on the granulation of the vanadium titano-magnetite concentrate were investigated by using micro-drum granulation equipment.The results show that there exist great difference in the particle size distribution index（PDI） of different kinds of quicklime after hydration with water.The main reasons for the great difference of PDI are chemical composition and mineral structure.The PDI has positive correlations with the granulation index（GI）,uniformity index（UI）,and resistance index of the thermal disintegration（KI）,but has negative correlations with the damage index（DI） of vanadium titanium magnetite concentrate.The effect of PDI on the DI is comparatively low for low-titanium magnetite concentrate compared with the other two concentrates.The quicklime with high particle size distribution index is good for its uniform distribution in the sinter mixture.The heat from hydration action of the quicklime can make the lime particles in the quasi-particles shrunk,and the particles in the quasi-particles are bonded more tightly and the isotropic thermal stress is more balanced,which is beneficial to the improvement of the hot property of the quasi-particles.

Research on Strength Properties of Vanadium-titanium Magnetite Tailings Pellets with Carbon-containing

Li Junhan, Sun Ning, Wu Mei

2019, 40(6): 90-95. doi: 10.7513/j.issn.1004-7638.2019.06.018

Abstract(303) PDF(7)

Abstract:
Using Panzhihua vanadium-titanium magnetite tailings as raw materials and polyvinyl alcohol as binding agent,the influences of the particle size composition,the moisture content,the pressure,the content of polyvinyl alcohol and the carbon content on the strength of resulted pellets were studied in this paper.The results showed that the pellet strength increased firstly and then decreased with the grain size refinement and increase of the moisture content,and gradually increased with the increase of polyvinyl alcohol content.Besides,with the increase of the pressure,the compressive strength changed with "N" shape,and the drop strength increased firstly and then decreased.With the increase of carbon content,the compressive strength first increased and then decreased,and the drop strength gradually decreased.The optimized technology parameters obtained were that the tailings contain minus 75 μm was 40%,the moisture content 8%,the pressure 8 MPa,the content of polyvinyl alcohol 0.6% and the carbon content 15%.Under these conditions,the compression strength of the pellets was 185.4 N and the drop strength was 42.5 times,which was fully meet the requirements for pellet strength in industrial production.

Molecular Dynamics Simulation of Structure and Stability of Titanium Carbides Cluster in Iron Matrix

Lü Yanan, Chen Dong, Zhang Shunhu

2019, 40(6): 96-100. doi: 10.7513/j.issn.1004-7638.2019.06.019

Abstract(211) PDF(3)

Abstract:
The simulation of titanium carbide cluster in high strength low alloyed steel was carried out through discussing the cluster structure and stability by using molecular dynamics（MD） method.Titanium carbide cluster associated with iron matrix was investigated and compared with corresponding independent titanium carbide clusters via studying the structural change,energy property and cluster stability.The influences of cluster size and composition on cluster structure and stability were analyzed.The results show that the iron matrix has a significant impact on the structure of titanium carbide cluster.Cluster size and composition greatly affect the cluster structure and stability,and the structure difference increases with the increase of cluster size.Furthermore,the titanium carbide cluster with C/Ti of 2 generates the strongest stability.

Large Eddy Simulation of Fluctuation Behavior of Free Surface in the Continuous Casting Mould

Zhao Peng

2019, 40(6): 101-107. doi: 10.7513/j.issn.1004-7638.2019.06.020

Abstract(224) PDF(4)

Abstract:
Large Eddy Simulation（LES） method describing behaviour of the fluctuation of free surface in continuous casting mould was constructed.The accuracy of mathematical models was also verified by water experiments.The transient flow field and free surface fluctuations inside the mould were studied.Fluctuation height,velocity and turbulent energy of free surface were also quantitatively analyzed.The results show that the flow fields with unsteady characteristics affect transient fluctuation of free surface inside the mould.The free surface fluctuates sharply in the vicinity of the middle position between SEN nozzle and the narrow wall,and fluctuation height and velocity of free surface on both sides of SEN inside the mould show an asymmetrical distribution in the space-time range.

Refining Process Optimization of Vanadium-bearing Steel 20CrMoV for Automotive Gear

Ye Yanxian, Yu Jiaojiao

2019, 40(6): 108-112. doi: 10.7513/j.issn.1004-7638.2019.06.021

Abstract(156) PDF(4)

Abstract:
In order to optimize the refining process of 20 CrMoV automobile gear steel containing vanadium,the refining tests of 20 CrMoV steel samples at different refining time（20～60 min）and soft blowing time（10～50 min）were carried out.The oxygen content and hydrogen content in the steel samples were measured,and the wear resistance was tested and analyzed.The results show that the oxygen content,hydrogen content and wear volume of steel samples decrease firstly and then increase with enlarging refining time and soft blowing time.Compared with refining time for 20 min,when the refining time is 50 min,the oxygen content reduces by 27.59%,the hydrogen content decreases by 64.52% and wear volume reduces by 46.15%.Compared with blowing time for 10 min,when the blowing time is 30 min, the oxygen content reduces by 14.85%,the hydrogen content decreases by 62.07% and wear volume reduces by 41.67%.The optimized refining time and soft blowing time of 20 CrMoV vanadium-bearing automobile gear steel are 50 min and 30 min,respectively.

Development of Hot Rolled Ribbed Bars for V-N Micro-alloyed HRB500E

Guo Yuehua

2019, 40(6): 113-117. doi: 10.7513/j.issn.1004-7638.2019.06.022

Abstract(225) PDF(9)

Abstract:
The difficulty in developing the HRB500 E hot-rolled ribbed steel bars is not only to satisfy the high strength,but also ensure that the ratio of tensile/yield strength required for seismic resistance is greater than or equal to 1.25.Some domestic steel mills utilize the VN16 alloying process to produce HRB500 E,but the ratio of tensile/yield strength(R_m/R_eL) is hard to reach 1.25.In view of the above problems,the "VN16+FeV80" V-N alloying process is added to control vanadium and nitrogen contents between 0.07%～0.11% and 0.011%～0.015%,respectively.Precipitation strengthening effect of vanadium had played its role,but on the other hand,excessive precipitation of vanadium had been avoided in order to control reasonable the R_m/R_eL.Through controlling the vanadium precipitation,HRB500 E hot rolled rebars of ø12～ø32 mm specifications had been successfully developed.

Effect of Vanadium Content on Properties of New High Strength Steel

Li Mei, Wang Qiang, Gao Hongwen, Han Quanye, Zhang Keming

2019, 40(6): 118-121,142. doi: 10.7513/j.issn.1004-7638.2019.06.023

Abstract(272) PDF(10)

Abstract:
In order to study the effect of vanadium content on the properties of Q690-0.5 Al-0.5 In high strength steel,the base chemistry Q690-0.5 Al-0.5 In steel with different vanadium contents had been prepared,and the impact and tensile properties of the samples were measured and analyzed.The results show that with the increase of vanadium content,the impact absorbing energy and strength of the sample increase firstly and then decrease slowly,but the elongation decreases firstly and then increases slowly.Compared with 0.05%V steel,the impact absorption energy of 0.2%V steel increases by 23.27%,the tensile strength and yield strength increase by 42 MPa and 25 MPa,respectively.In order to improve the properties of Q690-0.5 Al-0.5 In new high strength steel,the optimum addition of vanadium is 0.2%.

Influence of Heating Rate on Recrystallization Texture of Cold Rolled Deep Drawing Steel Sheet

Tang Mengxia

2019, 40(6): 122-128. doi: 10.7513/j.issn.1004-7638.2019.06.024

Abstract(199) PDF(5)

Abstract:
The recrystallization annealing tests with different heating rate（2 ℃/min,20 ℃/min,350 ℃/min） and holding time（10 min,60 min,300 min） of CSP-DC04 cold rolled deep drawing steel sheet（wt%:0.02 C、0.03 Si、0.2 Mn、0.02 P、0.008 S、0.04 Als、0.007 N） had been conducted by a laboratory tubular resistance furnace.Microstructure and recrystallization texture were studied by means of electron back-scatter diffraction technology（EBSD）,X-ray diffraction（XRD） and metallographic microscope.The results showed that holding time has significant effect on the recrystallization texture,but little effect on the grain morphology.Heating rate has strong effect on the grain morphology and recrystallization texture.The grains are fine and equiaxed after fast heating rate annealing（350 ℃/min）,the α-fiber microtexture and γ-fiber microtexture strengthened with the increasing of holding time.Its nucleation mechanism is directional nucleation-sub grain merge nucleation.However,the grains are pancake-shaped along the rolling direction when annealing at slow heating rate（2 ℃/min）,the α-fiber microtexture weakened with the increasing of holding time but the γ-fiber microtexture strengthened firstly and weakened later with the increasing of holding time,its nucleation was controlled by selective growth-boundary bulge out nucleation mechanism.

Effect of Static Magnetic Field on Nucleation and Growth Orientation of Fe Atomic

Jin Yongli, Zhang Xiang, Zhang Jieyu, Hou Yanchao

2019, 40(6): 129-134,148. doi: 10.7513/j.issn.1004-7638.2019.06.025

Abstract(177) PDF(5)

Abstract:
In this paper,the effect of static magnetic field on nucleation and growth orientation of Fe atomic was researched from the perspective of crystal structure by the edge-edge matching model and electron backscatter diffraction（EBSD）technique.It is found out that the optimal orientation relation between Fe_xO and Fe is[010]//[110]＆（200）//（110） independent on magnetic field.during the conversion of Fe_xO→Fe,and Fe_xO preferentially precipitates α-Fe crystal nucleus on {100} crystal plane both under the action of magnetic field and conventional metallurgical conditions.A constant magnetic field（B=1 T） does not change the nucleation position of α-Fe on the wustite surface,but it has an impact on the growth orientation of α-Fe,causing it to deflect gradually from the preferential ＜100＞ direction to ＜100＞,＜101＞ and ＜111＞ directions.

Effect of Niobium on Microstructure Evolution and Behaviors of Second Phase Particles of the Reheated As-cast Grain-oriented Silicon Steel

Wang Yong, Li Guangqiang, Zhu Chengyi, Liu Yulong, Liu Yu

2019, 40(6): 135-142. doi: 10.7513/j.issn.1004-7638.2019.06.026

Abstract(149) PDF(4)

Abstract:
The grain oriented silicon steels with different Nb contents were prepared,and the effect of niobium on the microstructure evolution and the behaviors of second phase particles of the as-cast grain-oriented silicon steel during reheating process was studied by high-temperature confocal laser-scanning microscope（HTCLSM） and Nova 400 Nano field emission scanning electron microscope（FE-SEM）.The results show that the inclusions in all as-cast specimens are mainly complex inclusions,which takes Al₂O₃ as its core.During the cooling stage,MnS mainly precipitates in the first precipitation stage,and Nb（C,N） also precipitates in the Nb-containg specimens.And the volume fraction of the second phase particles in the first precipitation stage can be effectively increased by adding Nb,which will effectively enhance the pinning ability of the second phase particles.However,niobium has little effect on the behaviors of precipitation of AlN.Meanwhile,the homogeneity of microstructure of reheated specimens can be improved by adding Nb.

Microstructure and Properties Study of Warm-rolled 304 Austenite Stainless Steel with High Al Content

Guo Xin, Li Heng, Lu Xuefeng, Wei Yupeng, La Peiqing

2019, 40(6): 143-148. doi: 10.7513/j.issn.1004-7638.2019.06.027

Abstract(200) PDF(4)

Abstract:
304 austenite stainless steels with high Al content were warm-rolled and subsequently solution-treated.The effects of Al content and deformation amount on microstructure and properties were investigated.The surface appearance and composition were analyzed by means of OM,EPMA and SEM.The results show that the alloys are composed of gray austenite phase and black ferrite phase.The precipitates consist of an enriched phase containing aluminum nitride and other carbides.With the increasing of Al content,the volume fraction of ferrite increases.The yield strengths of the alloys with 1% Al under different deformation amount are 285 MPa,266 MPa and 273 MPa,respectively.Nevertheless,the yield strengths of the alloys with 1.5% Al are 350 MPa,365 MPa and 322 MPa,respectively.The fracture surfaces of the alloys are composed of large isometric dimples（5～30 μm） and smaller dimples（≤5 μm） arranged next to each other.The fracture models belong to ductile fracture.The alloys with 1% Al have higher tensile strength,while the sample with 1.5% Al has higher yield strength.The performance indicators of the samples are improved greatly,which provides important guidance for industrial production.

Effect of Mg on the Inclusions in 20CrMo Gear Steel

Fan Tian, Yang Qiankun, Xie Jianbo, Shen Ping, Fu Jianxun

2019, 40(6): 149-154. doi: 10.7513/j.issn.1004-7638.2019.06.028

Abstract(182) PDF(4)

Abstract:
In order to detect the effect of Mg on the inclusions in 20 CrMo gear steel,the smelting experiments of Mg addition to gear steel were carried out by using a high-temperature tube electric resistance furnace.Combined with the methods of SEM and OM,the morphology and composition of inclusions in this steel were characterized.And the change mechanisms of inclusion compositions in the steel were also investigated with thermodynamics under various Mg additions.Experimental results showed that the density of inclusions amount in steel was in range of 40～65 mm~2.With Mg content of 8×10^-6,the equivalent diameter of inclusions increased from 2.93 to 3.28 μm,whereas,with Mg content of（21～38）×10^-6,the equivalent diameter of inclusions was in range of 2.64～2.67 μm.With raising the Mg content in the steel,the percentage of single MnS inclusion reduced from 26.3% to 2.2%,while the percentage of oxides increased from 44.8% to 84.8%.Thermodynamics calculation indicated that the Mg with content of（2.63～7.98）×10^-6 could completely modify the Al₂O₃ into MgO·Al₂O₃ spinel; when Mg content is above 7.98×10^-6,MgO inclusions were generated.It is concluded that the proportion of composite inclusions at 8 ppm of Mg content was the maximum,whereas the proportion of oxides was relatively lower,which is beneficial to improving the mechanical properties of gear steel.

Optimization of Extrusion Process for New Energy Automotive Profiles Made from Titanium-magnesium Alloy

Wei Yun, Zhao Xing

2019, 40(6): 155-159. doi: 10.7513/j.issn.1004-7638.2019.06.029

Abstract(200) PDF(3)

Abstract:
The extrusion tests of Mg-Al-Zn-Ti new titanium-containing magnesium alloy for new energy automobile profiles were carried out with different extrusion temperature,extrusion speed and extrusion ratio,and the mechanical properties were tested and analyzed.The results show that the tensile strength and yield strength of the samples increase firstly and then decrease when the extrusion temperature is increased from 300 ℃ to 400 ℃,the extrusion speed is increased from 1 m/min to 5 m/min,and the extrusion ratio is increased from 10 to 26.Compared with the results from extrusion at 300 ℃,the tensile strength and yield strength of the specimen are increased by 17% and 31%,respectively,at an extrusion temperature of 360 ℃;compared with the results of extrusion speed of 1 m/min,the tensile strength and yield strength of the samples are increased by 14% and 23%,respectively when the extrusion speed is 4 m/min.Compared with the results of extrusion ratio of 10,the tensile strength and yield strength of the samples are increased by 9% and 14%,respectively,when the extrusion ratio was increased to 22.Therefore,the extrusion process optimization parameters of the new Mg-Al-Zn-Ti titanium-containing magnesium alloy for new energy automobile profiles are the extrusion temperature of 360 ℃,extrusion speed of 4 m/min,extrusion ratio of 22.

Study on the Causes of Falling-off of Welding Iron Oxide Scale in Pickle Sheet for Compressor

Du Yanling, Cao Xiao'en, Zhao Benfeng, Lu Chuanfang, Hong Yuntao, Kong Jiawei, Sun Bin

2019, 40(6): 160-166. doi: 10.7513/j.issn.1004-7638.2019.06.030

Abstract(152) PDF(4)

Abstract:
In this paper the reason for falling-off of welding iron oxide scale in pickle sheet had been investigated by comparing and analyzing chemical composition,microstructure,iron oxide structure,bath depth and sheet thickness of Hansteel’s sheet for Compressor.It is found out that the thickness of iron oxide scale of Hansteel is thicker than Baosteel and the proportion of the outer layer of Fe₃O₄ is higher than Baosteel. The difference in the thickness of Fe₃O₄ directly causes the falling-off of welding iron oxide scale of Hansteel.The content of C in SPHD-YSJ is low,leading to the iron oxide scale growth more rapidly during the welding process and thicker iron oxide scale,which is beneficial to the formation of Fe₃O₄.All those are the essential for the falling-off of the iron oxide scale.When increasing C content to 0.05%-0.07% and controlling the thickness based on micro-negative tolerance or zero tolerance,the welded iron oxide scale adhesion are improved and the problem of falling-off of the iron oxide scale has been successfully eliminated.

2019 Vol. 40, No. 6