钢铁钒钛

Preparation of TiO₂ from Panzhihua Titanium Slag by NaOH Decomposing-HCl Leaching

Liu Songliang, Sun Lin, Wang Jinjun, Wang Zhiyu

2019, 40(3): 1-6. doi: 10.7513/j.issn.1004-7638.2019.03.001

Abstract(69) PDF(1)

Abstract:
TiO₂ was prepared by a process of NaOH decomposing-HCl leaching with titanium slag from Panzhihua as raw material.The phase transformations of titanium slag during NaOH decomposition were analyzed using XRD.The results suggest that the decomposition of titanium slag by NaOH is a multistage process,viz.M₃O₅(M=Fe²⁺,Ti³⁺,Ti⁴⁺)→Fe₃Ti₃O₁₀ → Fe₂TiO₅ → α-NaFeO₂,Na₂TiO₃.The effects of HCl concentration,amount of Fe additive,solution pH,deposition temperature and time on the content of TiO₂ in the final products were studied during the HCl leaching process.The optimized conditions are determined at HCl concentration of 5 mol/L,Fe addition amount of 0.6 g,deposition time of 40 min,deposition temperature of 45℃ and solution pH=2,with 98.36% of TiO₂ in the final products.

Preparation of TC4 Alloy Powders Used for Laser 3D Printing via EIGA Method

Xie Bo

2019, 40(3): 7-12. doi: 10.7513/j.issn.1004-7638.2019.03.002

Abstract(340) PDF(16)

Abstract:
The preparation of TC4 alloy powders for laser 3 D printing(15~45 μm) via electrode induction melting gas atomization(EIGA) method was studied in this paper.The morphologies,phase compositions,particle size distributions,apparent densities and flowabilities of the powders were characterized by scanning electron microscopy(SEM),X-ray diffraction(XRD),laser particle size analyzer(LPS) and powder comprehensive characteristics tester,respectively.Meanwhile,the effects of gas atomization pressure and melt temperature on the yield of TC4 alloy powders were studied.The results indicate that the TC4 alloy powders have nearly regular spherical morphology,with a small amount of satellite balls adhering on the surface.The powder is α'-Ti of a single phase solid solution.With the increase of atomizing gas pressure and melt temperature,the yield of TC4 alloy powders increases first and then decreases.The optimum parameters are gas atomization pressure of 5 MPa,melt temperature of 1 800℃.Under the optimized conditions,the average particle size D₅₀ is 81.2 μm,the yield of 15~45 μm powders is 22.3%,the flowability is 42.5 s(50 g),the apparent density is 2.83 g/cm³ with oxygen content of 1 260×10^-6,which meet the requirements for laser 3 D printing.

Acidic Precipitation of Vanadium from High Concentration of Vanadium Solution by Ammonium Salt

Liu Dong, Xue Xiangxin, Yang He

2019, 40(3): 13-20. doi: 10.7513/j.issn.1004-7638.2019.03.003

Abstract(111) PDF(13)

Abstract:
Currently,the vanadium solution used for vanadium extraction,coming from the integrate process of sodium roasting and then water leaching of vanadium slag,has relatively lower vanadium concentration.It will produce a large amount of toxic waste water containing V⁵⁺,Cr⁶⁺,NH₄⁺,SO₄^2- and Na⁺ etc,which increases the cost of post-treatment and the risk of environmental pollution.In this paper,the feasibility of acidic precipitation of vanadium from high concentration of vanadium solution by ammonium salt was studied using ordinary vanadium solution with the concentration of vanadium increased as raw material.And the effects of ammonium addition coefficient(K),acid addition for the first time(pH₁),vanadium precipitation temperature(T),and acid addition for the second time(pH₂) on the recovery rate of vanadium and products grade were investigated.Moreover,XRF and ICP were used to analyze the vanadium concentration in solutions before and after vanadium extraction,grade and impurities content of products.The results show that the preparation of vanadium pentoxide from high concentration of vanadium solution is feasible.The optimum recovery rate of vanadium up to 99.83% can be obtained at 60 g/L of vanadium concentration,K=2,pH₁=5.0,T=90℃ and pH₂=2.0,with V₂O₅ purity of 99.99% which meets the standard of YB/T5304-2011.This study also provides a research basis for the industrial treatment of vanadium solution with low pollution and high efficiency.

Research on Application of Acidic Precipitation of Vanadium with Ammonium Salt in the Solution Containing Vanadium and Chromium

Jiang Lin, Fu Zibi, Wu Zhenxiu

2019, 40(3): 21-25. doi: 10.7513/j.issn.1004-7638.2019.03.004

Abstract(28) PDF(2)

Abstract:
The alkaline solution containing vanadium was used as the raw material,which was from the process of sodium roasting for vanadium slag.After the removal of silicon and phosphorus from the solution,sodium sulfate and chromic anhydride were added into the solution to prepare vanadium and chromium containing solution with a fixed composition.Then,the representative process for acidic precipitation of vanadium with ammonium salt was adopted to investigate the impacts of sodium,chromium and vanadium contents in the vanadium and chromium containing solution as well as the ammonium addition coefficient on the precipitation rate of vanadium and Na₂O content in the obtained V₂O₅.The results show that it is feasible to apply the acidic precipitation of vanadium with ammonium salt to the solution containing vanadium and chromium in a certain concentration range,which can achieve desirable effects.On the precondition of satisfying the high vanadium deposition rate and qualified products,the maximum permissible concentration of sodium in the solution is determined at c(Na)/c(V)=2.4(the content ratio of sodium to vanadium).As the concentration of vanadium increases,the maximum permissible concentration of chromium in the solution changes with c(Cr)/c(V)(content ratio of chromium to vanadium) gradually decreasing at c(Na)/c(V)=1.8.The solution containing 25 g/L of vanadium,24 g/L of chromium and 45 g/L of sodium was concentrated for vanadium precipitation,and the results indicate that a maximum 26 g/L of vanadium can be permitted for the increase of vanadium concentration via reducing the liquid to solid ratio in the leaching process.The obtained V₂O₅ meets the relevant quality requirements with ammonium addition coefficient of 1.5.Few influences of ions concentration and ammonium addition coefficient were found on the vanadium precipitation rate.This study can provide the guidance for vanadium precipitation in the solution containing vanadium and chromium.

Magnetic Separation and Enrichment Method of Ultrafine Vanadium-bearing Titanomagnetite in Panxi Region

Yang Zhaojun, Wang Fengyu, Luo Rongfei, Yuan Xiangyi

2019, 40(3): 26-29. doi: 10.7513/j.issn.1004-7638.2019.03.005

Abstract(99) PDF(4)

Abstract:
Pangang Group Mining Company is the largest supplier for titanium concentrate in China,which has solved the technical problems of titanium recovery through scientific and technological innovations.However,the recovery rate of ilmenite below-0.038 mm is very low,leading to the high content of-0.038 mm titanium dioxide in tailings.In order to improve the recovery rate of vanadium-titanium magnetite,this paper explored the magnetic separation enrichment effect of new ZQS high gradient magnetic separator for the ilmenite.When the feed grade of titanium dioxide of the new ZQS high gradient magnetic separator is 11.47% and the content of-0.038 mm ilmenite reaches 88.89%,the grade and recovery rate of titanium dioxide can reach 20.19% and 83.56% respectively,and the recovery rate of-0.038 mm ilmenite is 84.05%.The test proves that the new ZQS high gradient magnetic separator is very effective in recovering ultrafine ilmenite,with very high grade and recovery rate of the concentrate.The technology of magnetic separation is simple and has good industrial application prospects.

Effect of Phosphoric Acid on Preparation of Rutile Titanium Dioxide

Ma Weiping, Wang Bin, Wu Jianchun

2019, 40(3): 30-33. doi: 10.7513/j.issn.1004-7638.2019.03.006

Abstract(96) PDF(9)

Abstract:
The effect of phosphoric acid on the pH of metatitanic acid,the transformation of crude product into rutile,the achromatic force and the luminance of the samples was studied using the metatitanic acid hydrolyzed from titanium solution of ilmenite as raw material.The results show that the phosphate radical or hydrogen phosphate ionized from the phosphoric acid combines with the cations in the system to form precipitate,and the ionized hydrogen ions inhibit the ionization of metatitanic acid.With increase of the phosphoric acid content,the initial and terminal temperatures of the transformation of rutile crystals gradually increase.The content of P₂O₅ in the samples is positively correlated with the initial or terminal temperature of the transformation.In the potassium-phosphorus-aluminum salts treatment system,the achromatic force TCS and blue phase SCX of the samples decrease significantly at P₂O₅ content lower than 0.13%.When the P₂O₅ content is higher than 0.13%,the influence of phosphoric acid on TCS and SCX is not significant.Better brightness value of the crude product can be obtained at 0.15%~0.19% of P₂O₅ content.

Preparation of Li₄Ti₅O₁₂ by Mechanical Force-assisted Solid-state Method

Sun Zhenyu, Peng Cheng, Ma Shaobo, Han Qing

2019, 40(3): 34-38. doi: 10.7513/j.issn.1004-7638.2019.03.007

Abstract(79) PDF(4)

Abstract:
Lithium titanate(Li₄Ti₅O₁₂) samples were synthesized via mechanical force-assisted solid phase route using titanium dioxide and lithium carbonate as the initial titanium source and lithium source,respectively.The phase structure,morphology,particle size and electrochemical properties of the prepared Li₄Ti₅O₁₂ were investigated respectively by TGA-DSC,XRD,SEM,granulometer and lithium battery tester.2032 button batteries were prepared using the Li₄Ti₅O₁₂ samples,and the cycle performance and rate performance were studied.The results show that pure Li₄Ti₅O₁₂ can be synthesized via mechanical force-assisted solid phase route at 750℃ for 3.5 h,with the uniform particle size of 0.6~2.5 μm,the initial discharge specific capacity of 152.02 mAh/g and 96.5% of the capacity retention rate after 20 times of charge-discharge cycle.

Experimental Study on the Preparation of Ti-Al Based Alloy by Aluminothermic Reduction-Vacuum Electromagnetic Levitation Refining of Waste Denitration Catalyst

Piao Rongxun, Ma Lan, Yang Shaoli, Zhou Lisha, Li Ping

2019, 40(3): 39-45. doi: 10.7513/j.issn.1004-7638.2019.03.008

Abstract(66) PDF(1)

Abstract:
Experimental study on the preparation of Ti-Al based intermetallic alloy from selective catalytic reduction(SCR) Ti-based denitration catalyst was first conducted by using aluminothermic reduction followed with the vacuum electromagnetic levitation melting.Using SEM and XRD analyses,it is found that the alloy is mainly composed of TiAl₂,Ti₅Si₃ and TiAl phases while the impurities mostly exist as the form of oxides and carbides.With the refining of the alloy,the composition of Ti-Al compound changes from Ti-rich to Al-rich titanium aluminide,and the impurities content decreases gradually with more than 85% of the total impurity removal rate after three times of refining.Finally,the hardness test was performed and it shows increase tendency with increase of refining times.This is due to the increase of TiAl₂ phase with high hardness and the decrease of TiAl phase with low hardness.

Effect of Sintering Process on Microstructure and Mechanical Properties of Porous Ti-5Cu Alloy

Mai Ping, Cui Xumei, Zhao Chaoyong, Zhang Xuefeng, Yao Lianjie

2019, 40(3): 46-53. doi: 10.7513/j.issn.1004-7638.2019.03.009

Abstract(87) PDF(2)

Abstract:
Porous Ti-5 Cu alloy with anisotropic porous structure was prepared by powder metallurgy method using 40% of spherical stearic acid as the space holder agent,and the effect of sintering process on the microstructure and mechanical properties of the porous Ti-5 Cu alloy was studied.The results show that the sintering temperature and holding time have no obvious effects on the phase compositions of porous Ti-5 Cu alloy,but they have great influences on the microstructure and mechanical properties of the alloy.Porous Ti-5 Cu alloy with good pore structure and mechanical properties can be prepared by vacuum sintering at 900℃ and holding for 2 h,with 68.25% of porosity,89.00 MPa of compressive strength and 3.79 GPa of elastic modulus.The obtained alloy has the similar mechanical properties with human bone and has the potential to be used as bone repair material.

Effect of Surface Treatment by Aluminium Hydroxide on Properties of Rutile Nano-TiO₂

Wu Jianchun

2019, 40(3): 54-59. doi: 10.7513/j.issn.1004-7638.2019.03.010

Abstract(57) PDF(3)

Abstract:
At temperature of 55~60℃ and pH=9.5~10.0,inorganic surface treatment was carried out with sodium metaaluminate for 30 nm titanium dioxide.The particle size distribution,zeta potential,UV-visible spectrum and thermal endurance of the sample before and after surface treatment were compared and analyzed.Then,optically variable car paint was prepared with aluminiumpaste and nano-titanium dioxide before and after inorganic surface treatment,and the weather resistance and optically variable performance were compared.The results show that compared with those of raw nano-TiO₂,the particle size distribution of nano-titanium dioxide after surface treatment by aluminum hydroxide is more uniform,and the zeta potential of the surface modified nano-TiO₂ changes from negative to positive value with stronger ultraviolet absorption intensity,and improved temperature resistance and weather resistance.The optically variable performance of the nano-TiO₂ does not change much by surface modification.

Wear Behaviors of Vanadium and Titanium Modified NM450 Steel

Li Huiying, Zhang Yao, Xie Zun

2019, 40(3): 60-64. doi: 10.7513/j.issn.1004-7638.2019.03.011

Abstract(28) PDF(1)

Abstract:
Vanadium and titanium elements were added to modify the common NM450 steel.The results show that compared with those of NM450 steel,the weight loss,the depth and area of wear marks of NM450-0.2 V specimens with vanadium added are reduced by 5.36%,11.11% and 27.27% respectively,and the weight loss,the depth and area of wear marks of NM450-0.2 Ti specimens with titanium added are respectively reduced by 8.93%,13.89% and 36.36%,meanwhile,the weight loss,the depth and area of wear marks of NM450-0.2 V-0.2 Ti with vanadium and titanium simultaneously added are decreased by 16.07%,23.61% and 54.55%,respectively.Modification with vanadium and titanium is beneficial to improve the wear properties of NM450 steel,and the NM450-0.2 V-0.2 Ti specimens simultaneously with vanadium and titanium have the best wear properties.

Effect of Ti-Sr Composite Addition on Properties of Die Steel for Casting of Automobile Parts

Song Wei, Yao Qihong

2019, 40(3): 65-69. doi: 10.7513/j.issn.1004-7638.2019.03.012

Abstract(50) PDF(1)

Abstract:
In this paper,3Cr2W8V die steel for casting of automotive parts was modified by Ti-Sr composite addition,and the results of high temperature wear test and thermal fatigue test were analyzed.The results show that the addition of Ti and Sr has an important effect on the wear resistance and thermal fatigue properties of 3Cr2W8V die steel.Compared with the 3Cr2W8V die steel without Ti and Sr,the wear volume,the average width and depth of the main crack for the steel with 0.3% Ti and 0.3% Sr respectively decrease by 35.7%,44.8% and 57.1%.The wear resistance and thermal fatigue properties of the die steel with 0.3% Ti and 0.3% Sr are improved.

Study on Electrochemical Corrosion Behaviors of Enamel Coating Prepared from Titanium Tailings

Shu Mingyong, Yin Haiying, Zhong Qingdong

2019, 40(3): 70-76. doi: 10.7513/j.issn.1004-7638.2019.03.013

Abstract(47) PDF(1)

Abstract:
The enamel coating was prepared from the titanium tailings in Panzhihua area,and the electrochemical corrosion behaviors of the enamel coating in 30% HCl solution were studied using potentiodynamic polarization curve(Tafel) and electrochemical impedance spectroscopy(EIS).The results show that the amount of bubbles in the enamel coating and the iron oxides-iron phase dendrite structures increase,and the island and anchor structures are obviously embedded into each other,with the increase of the addition of titanium tailings.The polarization curve E_corr of the enamel coating in 30% HCl solution decreases with the increase of titanium tailings content,and the corrosion rate increases.A large radius of capacitive reactance arc is found in the high-frequency region of electrochemical impedance spectroscopy Nyquisy,and the diffusion effect can be observed in the low-frequency region where the phase angle θ is near 5° and log|Z|~logf diagram approximates to a horizontal line.The coating presents as pure resistance with high impedance.Therefore,the optimal content of titanium tailings is 8%~10%.

Preparation of High Strength Concrete from Vanadium Titanomagnetite Tailings

Wang Xiugui, Qin Lianyin

2019, 40(3): 77-82. doi: 10.7513/j.issn.1004-7638.2019.03.014

Abstract(67) PDF(3)

Abstract:
To comprehensively utilize the vanadium titanomagnetite tailings from Chengde area,the high strength concrete products were prepared using the tailings,cement clinker,blast furnace slag and gypsum as raw materials.The effects of fineness of tailings,dosage of tailings and water reducer on the compressive strength and fluidity of the samples were studied.The composition and structure of the samples were analyzed.The sulfate corrosion resistance and permeability resistance of the samples were tested.The results show that the compressive strength of cement mortar increases first and then decreases with the increase in tailings and water reducer dosage as well as decrease of tailings particle size.The fluidity of cement mortar increases with increasing the tailings fineness and water reducer dosage,and the early compressive strength of cement mortar decreases with the tailings addition.When the dosage of tailings,cement,blast furnace slag,gypsum and water reducer is respectively 60%,24%,12%,4% and 1%,and the tailings with-0.074 mm particle size account for 80.44% in amount,the 28-day compressive strength of concrete products reaches 90.2 MPa,which meets the requirements of C50~C80 grade in Technical Regulations for High Strength Concrete Structures.The results of XRD and SEM analysis show that after curing for 28 d,plate-like tobermorite,needle like ettringite and amorphous hydrated calcium silicate can be formed.Hydrated calcium silicate gel tightly cemented coarse aggregate,giving the sample high compressive strength,excellent sulfate resistance and permeability resistance.

Non-isothermal Reduction Kinetics of Carbon Coated Iron Powder

Hao Suju, Lan Jiran, Jiang Wufeng, Zhang Yuzhu

2019, 40(3): 83-87,92. doi: 10.7513/j.issn.1004-7638.2019.03.015

Abstract(36) PDF(1)

Abstract:
Iron-carbon solid-solid reduction reaction has always been a challenge for researcher,therefore,studying the solid-solid reaction kinetics has important practical significance.The mechanical grinding method was used to coat the magnetite with carbon and the differential thermal analysis was conducted on the ore powders with the milling time of 15 s,45 s,75 s and 105 s at a heating rate of 10 K/min.The mineral powder with the milling time of 105 s was selected to study the change rule of weight loss of coated ore powder under the condition of heating rate of 5 K/min,10 K/min,15 K/min and 20 K/min.The FWO method and the Coats-Redfern method were used to analyze the experimental data to get the related kinetic parameters of carbon-coated slag.The experimental results show that the weight loss of carbon coated slag is proportional to the temperature and grinding time within a certain range.The initial activation energy of solidification reaction of carbonaceous coated iron ore powder is 337 kJ/mol,the reaction model is three-dimensional diffusion model,the reaction model function is.

Effect of Slags on Desulfurization of Molten Iron/Semi-steel Containing Vanadium and Titanium

Yang Biwen, Song Bo, Guo Kai, Chen Liang

2019, 40(3): 88-92. doi: 10.7513/j.issn.1004-7638.2019.03.016

Abstract(61) PDF(3)

Abstract:
Effects of the chemical compositions and phases of the slags on desulphurization of molten iron and semi-steel were studied.Sulfur content in the desulfurized slag is 4~5 times higher than those of BF slag and vanadium-extracting slag.Sulfur exists in the form of CaS in the desulfurization slag,no MgS has been found.The average content of CaO in the semi-steel desulfurization slag is 15% less than that in the molten iron desulfurization slag,but FeO content is 9% more than that of later slag.The low melting point phases are few in the slag aftrer molten iron desulfurizationand mainly are mCaO·nAl₂O₃(<1 400℃).But for semi-steel desulfurization the low melting point phases has much higher content in the slag,mainly are FeO(1 369℃).Increasing desulfurizer injection amount can improve the sulfur control capacity of desulfurization slag,reducing resulfurization.BF slag as the top slag in the molten iron desulfurization process is 0.01~0.02 t/t,and the same as for vanadium-extracting slag.

Rare Earth Ce on Thermodynamics of Titanium Containing Inclusions in Steel and its Experimental Research

Lü Yong, Peng Jun, Cai Changkun, Ren Hongzhi, Zheng Lili, An Shengli

2019, 40(3): 93-98. doi: 10.7513/j.issn.1004-7638.2019.03.017

Abstract(67) PDF(4)

Abstract:
In this paper the Factsage7.0 software had been used to calculate the precipitation of titanium-bearing inclusion in the temperature range of 800~1 600℃. The size and morphology of titanium-bearing inclusion of steel with/without adding rare earth had been observed by scanning electron microscopy(SEM) and energy spectrum.Thermodynamics calculation and SEM results show that adding rare earth element Ce can reduce content of harmful elements such as S and O in steel,and thus the Ti₄C₂S₂ and Ti₃O₅ precipitates can be reduced.Therefore,effective Ti content can be increased,which leading to a increasing amount of fine dispersion of Ti(C,N) precipitation.Rare earth Ce can effectively modify the large size TiC-AlO₃ compound inclusions with hard edges and corners into a relatively small size,shape is oval TiC-CeAlO₃ clip,which can reduce the harmful effect of former inclusion shape on properties of steel.

Silicon Control of Low Carbon and Low Silicon Steel with LF Refining

Chen Yonghong, Yang Longchuan, Tang Haiming, Hu Wenjia

2019, 40(3): 99-103. doi: 10.7513/j.issn.1004-7638.2019.03.018

Abstract(90) PDF(2)

Abstract:
Analysis of controlling silicon content for low carbon and low silicon steel had been conducted from various aspects in this paper.Thermodynamics calculation results indicates that when in low-carbon and low Silicon steel and responding balanced silicon is,which implies that silicon pick-up is inevitable.Controlling the thickness of slag ≤ 100 mm after converter tapping and deep deoxygenation of the converter are helpful for silicon controlling. Control of acid aluminum in converter outlet at around 300×10^-6,and aluminum control ≤ 600×10^-6in the refining process can greatly reduce the amount of silicon recovery.Increasing the basicity by adding additional lime is good for inhibiting SiO₂ reduction and reducing the presence of glass slag and dark green slag is conducive to reducing the amount of silicon pick-up.Both controlling gas flow during refining process and using the combination of lime,fluorite and aluminum wire can reduce silicon pick-up and reduce the influence of smelting time on silicon prick-up.

Development of X70QPSL2 Tube for High Pressure Gas Transmitting Linepipe

Jiang Shichuan

2019, 40(3): 104-111,117. doi: 10.7513/j.issn.1004-7638.2019.03.019

Abstract(31) PDF(2)

Abstract:
The X70 QPSL2 seamless steel pipes with wall thickness S(>25 mm) for high pressure gas transmitting has been successfully developed by suitable alloyingdesign,integrated smelting control technology,controlled forging-compression ratio rolling and controlled cooling process,and external spray and internal axial flow process for heat treatment.The testing results and evaluation of the products show that the chemical composition,longitudinal tensile properties and Charpy V notch impact properties of the products meet the technical requirements.The average yield strength,tensile strength,yield ratio and elongation are 559 MPa,649 MPa,0.85,25% respectively.The transverse impact energy of the V type of 10 mm×10 mm×55 mm at 0℃ and-50℃are 213 J and 180 J respectively.Hydrostatic pressure test is qualified under 50 MPa high pressure.Welding performance evaluation indicates that the tube has excellent welding performance.

Methodological System to Describe Uniaxial Ratcheting Behavior of HRB400Ⅲ Aseismic Reinforced Bars

Duan Heng, Yao Ji, Fu Lei, Huang Kun, Luo Yunrong, Xie Wenlin

2019, 40(3): 112-117. doi: 10.7513/j.issn.1004-7638.2019.03.020

Abstract(40) PDF(1)

Abstract:
An experimental study was carried out on the cyclic ratcheting of HRB400Ⅲ aseismic reinforced bars subjected to asymmetric cyclic loading at room temperature.The effects of stress amplitude,mean stress and stress rate on HRB400Ⅲ aseismic reinforced bars were investigated completely.The experimental results indicated that increase of either stress amplitude or mean stress increased the ratcheting strain accumulated in the material.Under low stress amplitude,the intragranular back stress would hinder the accumulation of ratchet strain,meanwhile,ratcheting strain increased with the increase of stress rate.However,at high stress rate,the fatigue life of the material increased.During asymmetric cyclic loading,the strain energy density increased with the increase of stress amplitude and average stress.The material showed obvious cyclic hardening characteristics under cyclic loading.

Influence of Alloying Elements on the Precipitation Phase and High-temperature Endurance Property of Blade Steel KT5331

Wang Hongli

2019, 40(3): 118-123. doi: 10.7513/j.issn.1004-7638.2019.03.021

Abstract(37) PDF(1)

Abstract:
The influence of alloying elements on equilibrium precipitation phases of KT5331 were studied by Factsage software and experiment.The results show that the amount of M₂₃C₆ carbide is determined by C content in steel.The fluctuation of Cr,Mo content in steel has effect on precipitation temperature of M₂₃C₆.The amount of Laves phase is determined by the W content.Based on the influence of alloying elements on the precipitated phase,the influence of alloying elements on the high-temperature endurance property of KT5331 steel was analyzed.The results showed that in order to achieve high temperature durability of KT5331 steel,the C content should be reduced and the Cr and W elements are at the lower level,and the Mo element content is at the middle or upper limit.

Study on the Hot Ductility of High Nb and Ti Micro-alloyed Steel

Liang Wen, Hu Jun, Liu Wenyan

2019, 40(3): 124-130,141. doi: 10.7513/j.issn.1004-7638.2019.03.022

Abstract(61) PDF(5)

Abstract:
The hot ductility of high Nb and Ti micro-alloyed steel had been investigated through the high temperature tensile test and optical microscopy,scanning electron microscopy,transmission electron microscopy and micro-hardness tester.The results show that the relationship between the rate of reduction in area and the temperature range from 600~1 200℃ was V-shape for the high Nb and Ti micro-alloyed steel.The rate of reduction in area was the lowest at 800℃ while that was the highest at 1 200℃.The third brittle zone for the high Nb and Ti micro-alloyed steel was 680~910℃.The main reason for the embrittlement was the large-size carbonitrides and pro-eutectoid ferrite precipitated at the grain boundaries which weakened the grain boundary bonding force and provided conditions for crack generation and expansion.The micron-sized TiN particles in the sample were the main reason for the low rate of reduction in area of the high Nb and Ti micro-alloyed steel.The hot ductility at the third brittle zone can be improved by increasing the strain rate,shortening the time for the precipitation of pro-eutectoid ferrite and the growth of TiN particles and weakening the stress concentration during the tensile test.

Study on Electrochemical Corrosion of Nb Microalloy Steel

Dou Weixue, Guo Dong, Feng Jie, Zhu Miaoyong, Wang Xiaoli

2019, 40(3): 131-135. doi: 10.7513/j.issn.1004-7638.2019.03.023

Abstract(59) PDF(3)

Abstract:
In order to study corrosion properties of Nb microalloying high speed rail steel, heavy rail U75V steel (Cr 0.45%) with different Nb content had been investigated.The main causes of corrosion of high speed rail steel are explored by fitting curve analysis using CorrView electrochemical software based on constant potential measurement.The results show that the addition of Nb produces much more compact oxide layer, which is conducive to improvement of steel corrosion resistance.Nb can improve self-corrosion potential of steel substrate and can make oxide layer more dense. Corrosion current density of test steel containing 0.028% Nb is lower than the other test steel.Phase analysis of rust layer with different corrosion time shows that adding Nb is conducive to fast formation and quantity of α-FeOOH. α-FeOOH/γ-FeOOH ratio of test steel containing 0.028% Nb is higher than that of the other three kinds of steel. Therefore, this study provides a theoretical basis for composition optimization of high speed rail steel.

High Temperature Wear Performance of H13 Steel Laser Coating

Duan Mingwei, Wang Zhihang, Huang Yinghao, Ding Jie, Jiang Wei, Wang Shuqi

2019, 40(3): 136-141. doi: 10.7513/j.issn.1004-7638.2019.03.024

Abstract(55) PDF(3)

Abstract:
The H13 steel was selected for laser coating to obtain a laser cladding coating,and the microstructure and hardness were analyzed.The high temperature wear behavior of H13 steel coating was studied by pin-plate high temperature wear tester and compared with H13 steel substrate.The morphology,phase and composition of the ground surface were analyzed by microscopic analysis methods such as SEM,XRD and EDS,and the wear mechanism was discussed.The results show that under the same load condition,when the temperature is raised from 400℃ to 600℃,the grinding loss of the coating is significantly lower than that of H13 steel.When the temperature is 600℃ and the load is 150 N,the grinding loss of H13 steel is more serious.Plastic extrusion occurs on the worn surface,and the grinding loss increases,and the wear loss of the coating is much smaller than that of the H13 steel,indicating that the coating exhibits good wear resistance at high temperatures.At the same temperature,the wear loss of the coating and H13 steel increases with increasing load.At 400℃ and 50 N load,the wear mechanism of H13 steel and coating is slight wear,at 400℃ and 150 N load,the wear mechanism of H13 steel is oxidative wear,and the wear mechanism of the coating is slight wear,however,at 600℃ and 50 N load the wear mechanism of H13 steel is oxidative wear,while the wear mechanism of the coating is abrasive wear.At 600℃ and 150 N load,the wear mechanism of H13 steel is plastic deformation,and the wear mechanism of the coating is abrasive wear.

Effect of Heat Treatment on Salt Spray Corrosion Resistance of 12Cr13 Stainless Steel

Song Lingxi

2019, 40(3): 142-146. doi: 10.7513/j.issn.1004-7638.2019.03.025

Abstract(107) PDF(2)

Abstract:
The heat treatment test had been conducted on 12 Cr13 stainless steel,and the metallographic structure and carbide morphology of the resulted samples were observed,and the corrosion resistance and pitting potential of the samples were tested.The results show that the salt spray corrosion resistance of both normalized and normalized +350℃ tempered 12 Cr13 steel are the best,the salt spray corrosion resistance of normalized +750℃ tempered is good,butthe corrosion resistance of normalized +550℃ tempered is significantly deteriorated.The final heat treatment process of processed parts should avoid medium temperature tempering to ensure its corrosion resistance.

Study on the Properties of 3D Printed 5CrMnMo Hot Forging Die

Tong Yilin

2019, 40(3): 147-151. doi: 10.7513/j.issn.1004-7638.2019.03.026

Abstract(63) PDF(1)

Abstract:
The wear test and thermal fatigue test of 3 D printed 5 CrMnMo hot forging die steel and traditional manufacturing 5 CrMnMo hot forging die steel were carried out in this paper and the wear resistance and thermal fatigue properties were compared and analyzed.The results shows that wear loss of 3 D 5 CrMnMo hot forging die steel and traditional manufacturing 5 CrMnMo hot forging die steel are 3.9 g and 3.8 g respectively,and the grade of thermal fatigue crack are level 5 and 4,respectively.The wear performance of 3 D 5 CrMnMo hot forging die steel and traditional manufacturing 5 CrMnMo hot forging die steel are equal,and the difference in thermal fatigue properties between this two kinds of steels is small.3 D printing 5 CrMnMo hot forging die steel has good engineering application value.

Analysis of Linear Defects on Hot-dip Galvanized IF Steel Surface

Liu Xiaofei, Zhao Shunli, Gai Yanqing

2019, 40(3): 152-157. doi: 10.7513/j.issn.1004-7638.2019.03.027

Abstract(76) PDF(2)

Abstract:
The microstructure of single-long line and double-edged line defects on the surface of hot-dip galvanized sheets and hot-rolled sheets produced in the same time were analyzed by means of scanning electron microscope(SEM) and metallography.The results show that the entrapment of protective slag caused by crystallizer level fluctuation during continuous casting is the fundamental cause of such defects.By reducing the casting speed and increasing the insertion depth of the submerged nozzle properly,the slag entrapment can be effectively controlled by controlling the fluctuation of the liquid level within ±3 mm.At the same time,surface flame cleaning was used to handle those slabs with liquid level fluctuation exceeding ±5 mm during continuous casting.The occurrence rate of such edge linear defects can be greatly reduced.

2019, 40(3): 158-163. doi: 10.7513/j.issn.1004-7638.2019.03.028

Abstract(80) PDF(31)

Abstract:

Technologies and Qualities of the Whole-process Titanium Sponge in Panzhihua Iron and Steel Group

Jiang Baowei

2019, 40(3): 164-168. doi: 10.7513/j.issn.1004-7638.2019.03.029

Abstract(398) PDF(26)

Abstract:
The technical progresses and features of the whole-process titanium sponge were presented in this paper,relied on the largest proportion of titanium resources in Panxi area and the scientific layout made by Pangang Group.Based on the advantage of the whole industrial chain,the high quality titanium sponge prepared from the titanium ore was elaborated.This product has established a good foundation for the application of the high quality titanium and its alloy.

2019, 40(3): 169-170.

Abstract(38) PDF(1)

Abstract:

2019 Vol. 40, No. 3