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Formation and control of the surface defect in hypo-peritectic steel during continuous casting:A review 被引量:1
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作者 Quanhui Li Peng Lan +3 位作者 Haijie Wang Hongzhou Ai Deli Chen Haida Wang 《International Journal of Minerals,Metallurgy and Materials》 SCIE EI CAS CSCD 2023年第12期2281-2296,共16页
Hypo-peritectic steels are widely used in various industrial fields because of their high strength,high toughness,high processability,high weldability,and low material cost.However,surface defects are liable to occur ... Hypo-peritectic steels are widely used in various industrial fields because of their high strength,high toughness,high processability,high weldability,and low material cost.However,surface defects are liable to occur during continuous casting,which includes depression,longitudinal cracks,deep oscillation marks,and severe level fluctuation with slag entrapment.The high-efficiency production of hypo-peritectic steels by continuous casting is still a great challenge due to the limited understanding of the mechanism of peritectic solidification.This work reviews the definition and classification of hypo-peritectic steels and introduces the formation tendency of common surface defects related to peritectic solidification.New achievements in the mechanism of peritectic reaction and transformation have been listed.Finally,countermeasures to avoiding surface defects of hypo-peritectic steels duiring continuous casting are summarized.Enlightening certain points in the continuous casting of hypo-peritectic steels and the development of new techniques to overcome the present problems will be a great aid to researchers. 展开更多
关键词 hypo-peritectic steel continuous casting surface defect massive transformation grain coarsening DEPRESSION longitudinal crack level fluctuation oscillation mark
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M2C Precipitate in Isothermal Tempering of High Co-Ni Alloy Steel 被引量:1
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作者 HU Zheng-fei WU Xing-fang +2 位作者 LI Xiu-qiu WANG Chun-xu FANG Xin 《Journal of Iron and Steel Research International》 SCIE EI CAS CSCD 2001年第2期56-58,共3页
It is possible to measure different position along the axle direction of tappet. According to the maximum output of signal, the boundary of white iron structure and mottled iron structure can be deduced, and at the sa... It is possible to measure different position along the axle direction of tappet. According to the maximum output of signal, the boundary of white iron structure and mottled iron structure can be deduced, and at the same time, it is possible to use inductance displacement meter to show the chill depth which is the distance from the boundary to the end. 展开更多
关键词 magnetic permeability chilled cast iron chill depth
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Effect of droplet characteristics on liquid-phase distribution in spray zone of internal mixing air-mist nozzle
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作者 Wei-li Wu Chang-gui Cheng +2 位作者 Yang Li Shi-fa Wei De-li Chen 《China Foundry》 SCIE EI CAS CSCD 2024年第2期185-196,共12页
In continuous casting production,droplet characteristics are important parameters for evaluating the nozzle atomization quality,and have a significant impact on the secondary cooling effect and the slab quality.In ord... In continuous casting production,droplet characteristics are important parameters for evaluating the nozzle atomization quality,and have a significant impact on the secondary cooling effect and the slab quality.In order to study the behavior of atomized droplets after reaching the slab surface and to optimize the spray cooling effect,the influence of droplet diameter and droplet velocity on the migration behavior of droplets in the secondary cooling zone was analyzed by FLUENT software.Results show that the droplets in the spray zone and on the slab surface are mainly concentrated in the center,thus,the liquid volume fraction in the center is higher than that of either side.As the droplet diameter increases,the region of high liquid volume fraction on the slab surface becomes wider,and the liquid phase distribution in the slab width direction becomes uneven.Although increasing the droplet velocity at the nozzle exit has little effect on droplet diffusion in the spray zone,the distribution becomes more uneven due to more liquid reaches the slab surface per unit time.A prediction formula of the maximum water flow rate on the slab surface for specific droplet characteristics was proposed based on dimensionless analysis and validated by simulated data.A nozzle spacing of 210 mm was recommended under the working conditions in this study,which ensures effective coverage of the spray water over the slab surface and enhances the distribution uniformity of water flow rate in the transverse direction. 展开更多
关键词 continuous casting secondary cooling zone internal mixing air-mist nozzle droplet characteristics liquid phase distribution water flow rate
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Mechanism of Annealing Softening of Rolled or Forged Tool Steel 被引量:2
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作者 LIU Zong-chang GAO Zhan-yong +1 位作者 DONG Xue-dong DAI Jian-ming 《Journal of Iron and Steel Research International》 SCIE EI CAS CSCD 2003年第1期40-43,共4页
The steel specimens of nominal composition 0.3C-1.0Cr-1.0Mn-2.0Si-1.0Ni- 0.04 Nb were quenched and tempered or isothermally quenched from various temperatures. It is found that the steel quenched and tempered with a... The steel specimens of nominal composition 0.3C-1.0Cr-1.0Mn-2.0Si-1.0Ni- 0.04 Nb were quenched and tempered or isothermally quenched from various temperatures. It is found that the steel quenched and tempered with a tensile strength of 1 500-1 600 MPa has a K ISCC (critical stress intensity factor) value below 15.0 MPa·m 1/2 . The steel isothermally quenched with a tensile strength of 1 350-1 750 MPa has a K ISCC value about 20.0 MPa·m 1/2 . In addition, with increase of isothermal quenching temperature, the tensile strength decreases greatly and K ISCC value does not pronouncedly change. The microstructure of isothermally quenched specimens is composed of bainite and retained austenite. The delayed fracture resistance is dependent on the stability of austenite, which is in turn related to the retained austenite volume fraction and carbon content in austenite. 展开更多
关键词 high strength steel heat treatment mixed microstructure delayed fracture
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改善T91钢纯净度的相关研究
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作者 李涛 赵昌玲 +1 位作者 王哲 安杰 《工业加热》 CAS 2018年第2期31-34,共4页
以某钢厂T91钢生产实践为依据,生产流程为60 t电弧炉→AOD→LF→VD→240 mm×240 mm方坯连铸。钢中存在两种夹杂物形态,尺寸分别为10~200μm的块状Al2O3夹杂和直径≤33μm圆球状夹杂物。分析夹杂产生原因结果显示,块状Al2O3夹杂是... 以某钢厂T91钢生产实践为依据,生产流程为60 t电弧炉→AOD→LF→VD→240 mm×240 mm方坯连铸。钢中存在两种夹杂物形态,尺寸分别为10~200μm的块状Al2O3夹杂和直径≤33μm圆球状夹杂物。分析夹杂产生原因结果显示,块状Al2O3夹杂是随LF炉精炼过程的钒铁合金化操作混入钢水中,通过将钒铁合金化操作前移到AOD出钢至LF炉精炼初期期间予以解决。而圆球状夹杂物是钢水中的镁铝尖晶石与炉渣结合后形成的,改善是将AOD出钢炉渣碱度提高至2.0以上,AOD出钢脱硫率达到90%以上,从而提高炉渣吸附夹杂能力。 展开更多
关键词 夹杂物 AOD 合金化 AL2O3
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Effect of Cooling Rate on Microstructure and Mechanical Properties of 20CrNi2MoV Steel
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作者 Jian Zhang Chang-Sheng Li +2 位作者 Bin-Zhou Li Zhen-Xing Li Xue-Dong Pang 《Acta Metallurgica Sinica(English Letters)》 SCIE EI CAS CSCD 2016年第4期353-359,共7页
Thermo-mechanical process and continuous cooling process were carried out on 20CrNi2MoV steel. Three cooling rates were implemented to optimize the mechanical properties. The microstructure evolution, precipitation be... Thermo-mechanical process and continuous cooling process were carried out on 20CrNi2MoV steel. Three cooling rates were implemented to optimize the mechanical properties. The microstructure evolution, precipitation behavior, and strengthening mechanisms were systematically investigated, and the fracture mechanisms were analyzed via combination of impact fracture morphologies and deflection-load curves. The experimental results indicate that the transformed microstructure of experimental steel is all complex consisting of granular bainitic ferrite and bainitic ferrite with dispersed martensite/austenite (M/A) constituents in the matrix at cooling rates of 13, 21, and 29 ℃/s. When the cooling rate increases, the grain of the steel is obviously refined. The sizes of the bainitic ferrite are 5.8, 4.7, and 3.1 μm under cooling rates of 13, 21, and 29 ℃/s, respectively. The refinement of the bainitic ferrite plays a dominant role in strength increasing and also contributes to high crack propagation energy. However, the morphologies of M/A constituents obtained under different cooling rates contribute to different crack initiation energies and then affect the impact property. 展开更多
关键词 20CrNi2MoV steel MICROSTRUCTURE Cooling rate Mechanical properties
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High-Temperature Plasticity Enhanced by Multiple Secondary Phases in a High-Si Austenitic Stainless Steel
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作者 Sihan Chen Tian Liang +4 位作者 Guangcai Ma Chengwu Zheng Deli Chen Yingche Ma Kui Liu 《Acta Metallurgica Sinica(English Letters)》 SCIE EI CAS CSCD 2022年第9期1519-1530,共12页
An austenitic stainless steel with 6 wt% Si and multiple secondary phases was produced with the aim to achieve enhanced plasticity during hot deformation.The micro structure of the steel after fracture was characteriz... An austenitic stainless steel with 6 wt% Si and multiple secondary phases was produced with the aim to achieve enhanced plasticity during hot deformation.The micro structure of the steel after fracture was characterized via electron back-scattered diffraction,transmission Kikuchi diffraction and scanning transmission electron microscopy.From the tail of the gage to the necking region,the microstructure of the material evolved from low-angle grain boundaries(LAGB s) to mixtures of LAGBs and high-angle grain boundaries(HAGBs),and fine equiaxed recrystallized grains.The elongation to failure in the tensile test exceeds 167%.During the hot deformation,continuous dynamic recrystallization of the austenitic matrix was promoted by the multiple secondary phases.The dislocations introduced by the secondary phases were rearranged and continuously transformed into HAGBs.The initially coarse grains(30.5 μm) were refined into ultra-fine equiaxed grains(1 μm),which contributed significantly the enhanced plasticity during hot deformation of the steel.In the necking area of the sample,twins were nucleated in the stress concentration regions and accommodated the local strain by discontinuous dynamic recrystallization,which was also beneficial to improving the plasticity. 展开更多
关键词 High-Si austenitic stainless steel High-temperature deformation Plasticity enhancement Dynamic recrystallization Secondary phases
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Hot Deformation Behavior and Workability of a New Ni–W–Cr Superalloy for Molten Salt Reactors
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作者 Long Liu Zijian Zhou +5 位作者 Jie Yu Xinguang Wang Chuanyong Cui Rui Zhang Yizhou Zhou Xiaofeng Sun 《Acta Metallurgica Sinica(English Letters)》 SCIE EI CAS CSCD 2024年第8期1453-1466,共14页
The hot deformation behavior of a newly developed Ni–W–Cr superalloy for use in 800℃molten salt reactors(MSRs)was looked into by isothermal compression tests in the temperature range of 1050–1200℃with a strain ra... The hot deformation behavior of a newly developed Ni–W–Cr superalloy for use in 800℃molten salt reactors(MSRs)was looked into by isothermal compression tests in the temperature range of 1050–1200℃with a strain rate of 0.001–1 s^(−1)under a true strain of 0.693.An Arrhenius-type model for the Ni–W–Cr superalloy was constructed by fitting the corrected flow stress data.In this model,the effect of dispersion of solid solution elements during thermal deformation on microstructure evolution was considered,as well as the effects of friction and adiabatic heating on the temperature and strain rate-dependent variation of flow stresses.The hot deformation activation energy of the Ni–W–Cr superalloy was 323 kJ/mol,which was less than that of the Hastelloy N alloy(currently used in MSRs).According to the rectified flow stress data,processing maps were created.In conjunction with the corresponding deformation microstructures,the flow instability domains of the Ni–W–Cr superalloy were determined to be 1050–1160℃/0.03–1 s^(−1)and 1170–1200℃/0.001–0.09 s^(−1).In these deformation conditions,a locally inhomogeneous microstructure was caused by flow-i.e.,incomplete dynamic recrystallization and hot working parameters should avoid sliding into these domains.The ideal processing hot deformation domain for the Ni–W–Cr superalloy was determined to be 1170–1200℃/0.6–1 s^(−1). 展开更多
关键词 Ni-W-Cr Superalloy Hot deformation behavior Constitutive equation Processing map Microstructure evolution
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Effect of La on inclusions and fracture toughness of low-alloy ultrahigh-strength 40CrNi2Si2MoVA steel 被引量:7
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作者 Wei Gong Cheng Wang +3 位作者 Peng-fei Wang Zhou-hua Jiang Rui Wang Hua-bing Li 《Journal of Iron and Steel Research International》 SCIE EI CSCD 2021年第11期1408-1416,共9页
The effect of La on inclusions and fracture toughness of 40CrNi2Si2MoVA steel was investigated via the optical microscope,scanning electron microscope,image software and electronic universal testing machine.The result... The effect of La on inclusions and fracture toughness of 40CrNi2Si2MoVA steel was investigated via the optical microscope,scanning electron microscope,image software and electronic universal testing machine.The results reveal that the inclusions in steel without La are mainly MnS and Al_(2)O_(3)–MnS,while the inclusions in steels with La primarily contain La–O–S,La–S and other rare earth complex inclusions contain P and As.La–O–S and La–S are formed under the steelmaking temperature and act as the nucleation core of rare earth complex inclusions containing P and As.According to the segregation model,La–O–S–P–As and La–S–P–As are formed through chemical reactions during the solidification stage.As La content in steels increases from 0 to 0.032 mass%,the average spacing of inclusions is gradually increased from 5.28 to 15.91μm.The volume fraction of inclusions in steels containing less than 0.018 mass%La approaches 0.006%;however,it is significantly improved to 0.058%when La content is increased to 0.032 mass%.With the increase in La content,the fracture toughness is firstly improved from 63.1 to 80.0 MPa m^(1/2)due to the increase in average spacing of inclusions and then decreases to 69.6 MPa m^(1/2)owing to the excessive increase in volume fraction of inclusions.The optimal fracture toughness is found in 40CrNi2Si2MoVA steel with 0.018 mass%La. 展开更多
关键词 40CrNi2Si2MoVA steel LA INCLUSION Thermodynamic calculation Fracture toughness
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Application of FEM to Hot Continuous Rolling Process for Inconel 718 Alloy Round Rod 被引量:2
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作者 SUI Feng-li CHEN Li-qing +1 位作者 LIU Xiang-hua XU Li-xia 《Journal of Iron and Steel Research International》 SCIE EI CAS CSCD 2009年第5期43-49,共7页
A finite element model for coupled thermo-meehanical analysis has been developed in hot continuous rolling process for Inconel 718 alloy round rod with diameter of 45 mm. The stability of this alloy is discussed by in... A finite element model for coupled thermo-meehanical analysis has been developed in hot continuous rolling process for Inconel 718 alloy round rod with diameter of 45 mm. The stability of this alloy is discussed by integration of FEM and processing map reported in literatures. The result shows that the stability of Inconel 718 alloy is analyzed effectively during that process and good stability appears as the initial temperature is 960 ℃ and the initial velocity is from 0. 15 to 0.45 m · s^-1 or the initial temperature is 980 ℃ and the initial velocity is from 0. 15 to 0. 25 m · s^-1. 展开更多
关键词 hot continuous rolling elastic-plastic FEM coupled thermo-mechanical analysis processing map Inconel 718
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Hot Deformation Behavior of F6NM Stainless Steel 被引量:2
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作者 Long-teng MA Li-min WANG +3 位作者 Zheng-dong LIU Gang YANG Lun LU Meng-du PENG 《Journal of Iron and Steel Research International》 SCIE EI CAS CSCD 2014年第11期1035-1041,共7页
The hot deformation behavior of F6NM stainless steel was investigated by hot compression test in a Gleeble-1500D thermal-mechanical simulator. The flow strain-stress curves were obtained and the corresponding metallog... The hot deformation behavior of F6NM stainless steel was investigated by hot compression test in a Gleeble-1500D thermal-mechanical simulator. The flow strain-stress curves were obtained and the corresponding metallographic observation of this steel under different deformation conditions was also carried out. This steel exhibi- ted dynamic recrystallization (DRX) in the temperature range of 1 273- 1473 K and the strain rate range of 0.01- 0.1 s^-1. The activation energy for hot deformation was determined to be 457.91 kJ/mol, and the hot deformation equations were also established. The flow instability zone was determined and could be divided into two regions. The first one was located in the temperature range of 1 173- 1 348 K and the strain rate range of 0. 056-10 s^-1 , while the second one is in the temperature range of 1398-1448 K and the strain rate range of 1.25-10 s^-1. In the end, the optimum conditions for hot working were provided. 展开更多
关键词 F6NM steel dynamic recrystallization flow instability processing map
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Mechanism of Effect of Microwave Modification on Pulverized Coal Combustion Properties 被引量:1
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作者 Qing-hai PANG Jian-liang ZHANG +2 位作者 Rui MAO Zhe JIANG Tong LIU 《Journal of Iron and Steel Research International》 SCIE EI CAS CSCD 2014年第3期312-320,共9页
The mechanism of microwave modification or: facilitating the combustion properties of pulverized coal (PC) was investigated. Experimental researches on granularity and functional group as well as combustion propert... The mechanism of microwave modification or: facilitating the combustion properties of pulverized coal (PC) was investigated. Experimental researches on granularity and functional group as well as combustion properties of PC before and after modification were carried out. Micromorphology observation indicated that the size of PC par- ticles was relatively small, which was in accordance with the results of granularity analysis of PC. FT-IR (Fourier- transform infrared) spectra of two PCs indicated that the proportion of the functional groups with high activity in- creased after microwave irradiation. Furthermore, no valid effect of microwave was found on carbon matrix except small variations in PC particle size, which only led to subtle improvement in combustion of residual coke. Activation energies of Yungang and Yangquan PCs in temperature zone between 450--650 ℃ were reduced by 12.00% and 10.13%, respectively, which meant that microwave modification might effectively facilitate the combustion proper- ties of PC. Nevertheless, decrease in activation energies of residual cokes was 3.560% and 3.67% respectively, which was subtle and can be regarded as the result of smaller particle size produced by microwave irradiation. 展开更多
关键词 pulverized coal injection COMBUSTION MICROWAVE MODIFICATION
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Hot deformation characteristics and hot working window of as-cast large-tonnage GH3535 superalloy ingot 被引量:3
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作者 Yao Wang Junsong Wang +4 位作者 Jiasheng Dong Aimin Li Zhijun Li Guang Xie Langhong Lou 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 2018年第12期2439-2446,共8页
Deformation characteristics and range of optimized hot working parameters of a 6.5 tons GH3535 superalloy ingot with an average columnar grain size of over 1 mm in diameter were investigated. Axial compression experim... Deformation characteristics and range of optimized hot working parameters of a 6.5 tons GH3535 superalloy ingot with an average columnar grain size of over 1 mm in diameter were investigated. Axial compression experiments were performed in temperature range of 900-1240 ℃ and strain rate range of 0.001-30 s;at a total strain of 0.8. The hot deformation activation energy of the experimental GH3535 alloy is calculated to be 483.22 kJ/mol. Furthermore, the deformation constitutive equation is established by the peak stresses obtained from the stress-strain curves under various conditions. The hot working window of the alloy ingot at a strain of 0.8 can be preliminarily discussed based on the deformed microstructures and processing maps. The optimized hot working window was thus determined at the strain of 0.95 for 6.5 tons GH3535 alloy ingot by the supplementary compression tests. A large-size GH3535 superalloy ring with a dimension of 03010 mm x 410 mm was ultimately manufactured. 展开更多
关键词 Ni-base superalloy Dynamic recrystallization Hot working Large-tonnage ingot Processing map
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Hot cracking behavior of large size GH4742 superalloy vacuum induction melting ingot 被引量:4
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作者 Liang Zhang Lei Wang +3 位作者 Yang Liu Xiu Song Teng Yu Ran Duan 《Journal of Iron and Steel Research International》 SCIE EI CAS CSCD 2022年第9期1505-1512,共8页
The developing of large size superalloy vacuum induction melting(VIM)ingots is limited owing to hot cracking,The hot cracking behavior of the large size GH4742 superalloy VIM ingot was investigated via experiment and ... The developing of large size superalloy vacuum induction melting(VIM)ingots is limited owing to hot cracking,The hot cracking behavior of the large size GH4742 superalloy VIM ingot was investigated via experiment and simulation.The microstructure was examined by optical microscopy,and element segregation was investigated by electron probe microanalysis.The solidification temperature range and yield strength at high temperature(YSHT)were calculated by JMatPro software.The results show that the variations of microstructure and element segregation in different locations are caused by different cooling rates.Moreover,the larger secondary dendrite arm spacing and serious element segregation of Nb accelerate hot cracking of the VIM ingot.In addition,the solidification temperature range is wider,and YSHT is lower in center than at edge of the ingot.Therefore,the hot cracking susceptibility is the highest in the center of the GH4742 superalloy VIM ingot.The critical criterion of element segregation for hot cracking is that the partition coeffcient of Nb should be larger than 0.5. 展开更多
关键词 Hot cracking Large size-Superlloy Vacuum induction melting ingot Element segregation
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