钢铁钒钛

Study on Catalytic Mechanism of Gas-based Reduction of Iron Ore

ZHANG Linfeng, GUO Peimin, ZHAO Pei

2008, 29(1): 1-5.

Abstract(17) PDF(1)

Abstract:
Influence of alkali salt on gas-based reduction of iron ore was studied.For the same cation,the sequences of the catalytic effect F^->Cl^->I^->Br^- and NO₃^->OH^->CO₃^2->SO₄^2->PO₄^3- are shown. The new catalytic mechanism was proposed.Upon this theory,the catalytic effect of catalyst is attributed to Fe -O chemical bond influenced by catalyst.The effect of catalysts differs from the kinds of cations and anions and stabilization of compounds,which can be formulated as Ψ=αf(M⁺)+βf(X^-)-γ(T)f(MX)。

Research on Combustion Behavior of Powdered Coal Injection in Corex Smelting-gasifier

CAO Xirong, ZHANG Binghuai, JIA Guoli, YANG Haibin, ZHANG Tao, PENG Huaguo

2008, 29(1): 6-9.

Abstract(16) PDF(1)

Abstract:
The corex smelting reduction was a new kind of ironmaking process.The process need lump coal to maintain production,though coke is not necessary material for it.Powdered coal injection in corex smelting-gasifier was proposed in order to replace lump coal and make full use of powdered coal.The experience of PCI in BF can be learned by the corex technology,however,there are some different aspects between the two processes.The research on combustion behavior of powdered coal injection in corex smelting-gasifier was carried out by the themo-simulator.The rules of combustion rate and gasification rate were obtained,including these factors,such as the granularity of coal,the content of volatile compound,the blowing position and CO concentration.The research can provide essential theory for the development of powdered coal injection in corex process.

Effect of Annealing Processes on Microstructures and Textures of a Nb-Ti-IF Steel

ZHENG Zhiwang, WANG Minli

2008, 29(1): 10-16.

Abstract(26) PDF(1)

Abstract:
According to the processes of continuous hot-dip galvanizing lines,an industrially hot rolled and cold rolled Nb-Ti-IF steel was used to study the effect of annealing processes on the microstructures and recrystallization textures.The results showed that the steel was fully recrystallised above an annealing temperature of 720℃. When the annealing temperature is between 720℃and 840℃,the grain size is measured to be about ASTM grade 10.0 and it tended to grow to be ASTM grade 9.0 as the annealing temperature was increased to 880℃.When the annealing temperature was increased,the hardness of the experimental steel was decreased.However,although the grain was coarsened when the annealing temperature was 920℃,the hardness was increased when non polygonal microstructure was obtained due to water cooling after annealing.The change of holding time at 840℃from 30 s to 60 s had little effect on grain size.However,the hardness tended to reduce remarkably when the holding time was increased from 30 s to 45 s and remain almost constant when the holding time was further increased from 45 s to 60 s.Strong {223} <110>and {114} <110> texture components were fotmd after annealing,the intensity of them was little affected by the annealing processes while the intensity of {554} <225>,{111} <112> and {111} <110 > recrystallization texture tended to increase when the annealing temperature was increased.

Causes and Effects of Network Cracks in Continuously Cast Slab

CHEN Yong, ZHAO Zhangliang, SUN Yanhui, CAI Kaike

2008, 29(1): 17-22.

Abstract(24) PDF(1)

Abstract:
The results of microscope,SEM,TEM and EDS revealed that the particles precipitated in the preaustenite grain boundaries will result in network cracks under sufficient stress such as thermal stress,bending and straightening stress due to uneven cooling of strand surface.The influence of the carbon content,Mn/S and Al,V alloy additions and secondary cooling density on network cracks in slab of HSLA were also illustrated in this paper.The obtained results have made an important foundation for further controlling network cracks in continuously cast slab.

Effect of Heat Treatment Temperature on Microstructure and Properties of Dual-phase Steel Containing Chromium

ZHANG Kai-hua

2008, 29(1): 23-26,33.

Abstract(21) PDF(1)

Abstract:
The microstructure and properties of two series of galvanized dual-phase steel were researched with different heat treatment temperature at labor.The results show that pearlite exists at 780℃heat treatment. The microstructure of dual-phase steel is ferrite+martenite when heat treatment temperature is up to 800℃.The yield strength decreases with increaseing of heat treatment temperature,the yield strength decrease sharply when heat treatment temperature increases from 780℃to 800℃.The ratio of yield strength/tensile strength decrease with increaseing of heat treatment temperature.

Simulation of Mold Flow Field for the High Speed Slab Continuous Casting

WANG Yongsheng, GU Wu'an, WANG Xinhua, WANG Wanjun

2008, 29(1): 27-33.

Abstract(28) PDF(1)

Abstract:
With mathematical simulation,the influence of process parameter,such as submerged nozzle structure、flow control switch、outlet angle、submerged depth of nozzle、width and thickness of mold、argon blowing etc on fluid flow in mold,fluctuation and primary slab shell are studied in high speed continuous casting.The result showed that effect degree for process parameter to liquidity of steel in mold under high speed are larger than low speed.The fluctuating of steel level become severity,depth of impingement increased.Then the quality of slab will be deteriorated with the speed of slab continuous casting increaseing.The optimizing of the submerged entry nozzle and matching for mold and electromagnetic brake are important to high speed slab continuous casting.Flow beam of molten steel in mold under high speed has severe effects for primary slab shell, it's also one of cause for leakage of molten steel.

Experiments of Strain Ageing Sensibility of NVB Ship Plate Steel

HOU Dengyi, XU Hongqing, CHEN Ye

2008, 29(1): 34-37.

Abstract(10) PDF(1)

Abstract:
The effect of different plastic deformation strain ageing on the performance of NVB ship plate steel has been studied which includes strength,ductility,low temperature toughness and brittle-ductile transition temperature.As a result,NVB ship plate steel is less sensitive to strain ageing,and after 5% aged,low temperature toughness of plateis is still good.By means of microstructure analysis,microstructure and shear fracture morphology at different temperature are discussed.The results show,banded structure worsen toughness, nonmetallic inclusions has negative for brittle-ductile transition temperature.This article also expatiate strain ageing mechanism in dislocation aspect.

Study on Wear Resistance of High Cr-Ni Indefinite Chill Cast Iron Roller

WANG Jiang, HAN Jingtao, LIU Junxian

2008, 29(1): 38-42.

Abstract(35) PDF(1)

Abstract:
The wear resistance test for high Cr-Ni alloy indefinite chill cast iron roller was studied on a self-developed high temperature sliding wear and thermo-contact fatigue test machine.The surface morphology and surface structure of the roller were analyzed by surface copying technology,metallography and scanning electronic microscope.The results indicated that when the rolling kilometer reached 88 km,surface relief and spalling of carbide appeared on the roller surface of high Cr-Ni alloy indefinite chill cast iron.

Research on Secondary Refining Technology for Low-sulfur and High Strength Weathering Steel

RAN Menglun

2008, 29(1): 43-47,60.

Abstract(22) PDF(1)

Abstract:
Secondary refining technology for low-sulfur and high strength weathering steel was introduced,especially LF.The service condition and effect of the new material(the vanadium-titanium-micralloyed coreline)were detailed.As a result,the production became economic and efficient.Practice shows that through choosing reasonable desulfurization process and using new technologies of microalloying,the product composition(S、V、Ti、N、Ca etc.)of low-sulfur and high strength weathering steel is stable by LF refining,the mechanical properties and corrosion resistance is excellent also.

Research on Quantity of Coating Compact SiO₂ Film on the Surface of TiO₂

LI Qin, HU Hongfei, HOU Shengdong, CHEN Deming, WU Liangying, WEI Chang

2008, 29(1): 48-53.

Abstract(18) PDF(2)

Abstract:
Infulence of thermodynamics and salinity as agent on film formation are discussed,the minimum and maximum coating quantity of compact SiO₂ on the surface of TiO₂ are pointed out in this paper.On the basis of the analysis,coating test with different quantities of SiO₂ on the surface of TiO₂ are carried out and applicable properties of samples in these tests have been detected including acid solubility,oil absorption value,tint-reducing power,whiteness.Then the optimum coating of sillica on surface of TiO₂ is found.

Influence of MgO Content on Productivity and Quality of V-bearing Titaniferous Magnetite Sinter

GAN Qin, HE Qun, WEN Yongcai

2008, 29(1): 54-60.

Abstract(22) PDF(1)

Abstract:
According to the actual production conditions of Panzhihua Iron and Steel Group Co.,influence of MgO on productivity and quality of sinter was investigated in laboratory.The result showed that strength,production yield and metallurgical properties of sinter trends to improve with increasing of MgO content.Addtion of dolomite or high-magnesium content lime in sinter is effective measures at present,MgO<3.7% is reasonable in the V-bearing titaniferous magnetite sinter.

Study on Character at High Temperature and Requirement of Mold Fluxes for 2Cr13 Stainless Steel

WANG Wenxue, LIU Cailing, WANG Yu, YANG Ladao, ZUO Yanbing

2008, 29(1): 61-65.

Abstract(18) PDF(1)

Abstract:
The DIL402C thermal dilatometer,STA449C thermal analyzer,the type Gleeble-1500D thermal simulation testing machine were employed to test the linear expansion coefficient,major phase change temperature,mechanic properties at high temperature of 2Cr13.The effect of these properties at high temperature on surface quality of billet and the mechanism of surface depression and micro-crack formation on billet were analyzed.The study showed that heat transfer performance of mold fluxes for 2Cr13 stainless steel was vitally important.

Phase Transformation and Second-phase Precipitation Behavior of Nb-Ti Microalloyed Steel during Cooling after Deformation

WU Xinlang, ZHAO Zhengzhi, TIAN Yun, TANG Di, LIU Guangming, DAI Xiaoli, XIONG Aiming

2008, 29(1): 66-70.

Abstract(24) PDF(1)

Abstract:
The phase transformation behavior of Nb-Ti microalloyed steel during cooling process after deformation was studied by the Gleeble-2000 thermomechanical experiment simulator and by means of a combined method of microscopic hardness measurement.In addition,both second-phase precipitation behavior during cooling after deformation and the effect of cooling rate on the second-phase precipitation were studied by the carbon extraction replicas technique.The results show that there a lot of fine dispersed particles which are main Nb-Ti carbonitride phase are precipitated.The shape of the secondary phase particles is general like square、elliptical、circular shape and irregular shape.With the cooling rate increasing,the second-phase precipitation particles are seen to have become finer and the number of them are increasing.

Investigation of Spectroscopic Analysis on Titanium in Ferroalloy

LIU Ping, YANG Junhong

2008, 29(1): 71-74.

Abstract(18) PDF(1)

Abstract:
Characteristic of visible light spectrum was studied on titanium in ferroalloy by digital analysis system with grating spectroscope and prism spectroscope.The visible light spectrums of titanium and iron were simulated by computer and digital spectrums were shot by digital analysis system.The researches were made on characteristic of Ti499.95 nm,Ti551.25 nm and Ti489.99 nm line groups in ferroalloy.The analysis chart and intensity mark were obtained.The method was developed for spectroscopic analysis of titanium in ferroalloy.The research results can meet the requirements for qualitative analysis and semi-quantitative analysis on titanium in ferroalloy,can be used to exactly examine alloy and avoid the commixing of material on spot.

2008 Vol. 29, No. 1