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softening and melting behaviors of ferrous burden in hydrogen-rich blast furnace cohesive zone

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Journal of Iron and Steel Research International 2023年第12期30卷 2366-2377页

作者： Bin-bin Lyu Guang Wang Fan Yang Hai-bin Zuo Qing-guo Xue Jing-song Wang State Key Laboratory of Advanced Metallurgy University of Science and Technology BeijingBeijing100083China

The changes in the softening and melting behaviors of ferrous burden in the cohesive zone and the characteristics of the slag–iron–coke interface in a blast furnace were investigated by simulating an actual blast furnace under hydrogen-rich *** to the variation in the transient shrinkage of the burden under different atmospheres,the shrinkage start temperature of the sinter was higher than that of the *** negative shrinkage rate of the pellets was greater than that of the ***,the softening start temperature in the blast furnace decreased under hydrogen-rich conditions,giving the blast furnace a broader range of softening *** softening start temperatures of the pellets and sinter decreased from 1102 to 949℃ and 1152 to 1080℃,*** hydrogen-rich traditional blast furnace conditions narrowed the melting zone temperature range and shifted it toward the high-temperature zone,significantly improving the burden layer ***,under the hydrogen-rich oxygen blast furnace conditions,there were a decrease in the melting start temperature,a shift of the melting zone location to the low-temperature zone,and an increase in the burden layer permeability and pressure difference.A comparison of the slag–iron–coke interface characteristics under different atmospheric conditions showed that the carbon content in metallic iron decreased under hydrogen-rich traditional blast furnace conditions compared with traditional blast furnace ***,under hydrogen-rich oxygen blast furnace conditions,the carbon content in metallic iron increased compared with oxygen blast furnace *** findings provide guidance for the development of low-carbon ironmaking processes in blast furnaces.

关键词： Ferrous burden-Hydrogen softening Melting Cohesive zone Slag-iron-coke interface

softening and Melting Behavior of Mixed Burden for Oxygen Blast Furnace

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Journal of Iron and Steel Research International 2013年第5期20卷 11-16页

作者： AN Xiu-wei WANG Jing-song LAN Rong-zong HAN Yi-hua XUE Qing-guo State Key Laboratory of Advanced Metallurgy School of Metallurgical and Ecological Engineering University of Science and Technology Beijing

The behaviors of mixed burden in the cohesive zone of oxygen blast furnace were studied by softening and melting tests, and the influence of reducing gas and burden basicity on the softening and melting behaviors of mixed burden was also investigated. The results indicated that the softening range became wide, however, the melting range narrowed sharply in the atmosphere of oxygen blast furnace. The permeability of burden in the oxygen blast furnace was obviously improved comparing with the conventional blast furnace. In addition, the content of sulphur in the dripping iron of oxygen blast furnace was much lower than that of conventional blast furnace, however, the content of carbon increased. An optimum basicity of burden, which could lead to the appearance of the narrower melting range and better permeability of burden, was obtained in the atmosphere of oxygen blast furnace.

关键词： oxygen blast furnace softening melting mixed burden basicity reduction degree

softening of phonon spectra in metallic glasses

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npj Computational Materials 2016年第1期2卷 31-35页

作者： Reza Mahjoub Nicholas E Hamilton Kevin J Laws Michael Ferry School of Materials Science and Engineering The University of New South WalesSydneyNSWAustralia

The vibrational spectra of a series of MgZnCa amorphous alloys were computed using density functional theory and implementing the small displacement *** atomic structures of the alloys were obtained by ab initio molecular dynamics *** vibrational thermodynamic properties were calculated as a function of temperature and,in particular,the specific heat at low temperature was approximated by temperature cubed based on the Debye *** computed the contribution of Mg vibrations to the specific heat and investigated the softening of Mg phonon spectra,where the maximum allowed vibrational frequency is lowered and highly collective diffusion processes are *** statistical correlation between the reported critical casting thickness of the alloys and softening of Mg phonons was *** calculations were performed for two distinctively different amorphous ZrTiCuAl alloys with large and small reported critical casting thickness,*** findings were consistent with those of the MgZnCa alloys.

关键词： alloys softening casting

Effect of MgO content in sinter on the softening–melting behavior of mixed burden made from chromium-bearing vanadium–titanium magnetite

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International Journal of Minerals,Metallurgy and Materials 2016年第1期23卷 25-32页

作者： Zheng-gen Liu Man-sheng Chu Hong-tao Wang Wei Zhao Xiang-xin Xue School of Materials and Metallurgy Northeastern University

The effect of sinter with different MgO contents on the softening-melting behavior of mixed burden made from chro- mium-bearing vanadium-titanium magnetite was investigated. The results show that with increasing MgO content in the sinter, the softening interval and melting interval increased and the location of the cohesive zone shifted downward slightly and became moderately thicker. The softening-melting characteristic value was less pronounced when the MgO content in the sinter was 2.98wt%-3.40wt%. Increasing MgO content in the sinter reduced the content and recovery of V and Cr in the dripped iron. In addition, greater MgO contents in the sinter resulted in the generation of greater amounts of high-melting-point components, which adversely affected the permeability of the mixed burden. When the softening-melting behavior of the mixed burden and the recovery of valuable elements were taken into account, proper MgO con- tents in the sinter and slag ranged from 2.98wt% to 3.40wt% and from 11.46wt% to 12.72wt%, respectively, for the smelting of burden made from chromium-bearing vanadium-titanium magnetite in a blast furnace.

关键词： ironmaking magnetite magnesia softening melting behavior sinter blast furnace practice

Mesoscopic analysis of the utilization of hardening model for a description of softening behavior based on disturbed state concept theory

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2008年第9期9卷 1167-1175页

作者： Jian-ye ZHENG An-li WU Guangzhou Metropolis Construction Commission Guangzhou 510030 China College of Civil Engineering and Architecture lnner Mongolia University of Technology Hohhot 010051 China

Mesoscopic characteristics of a clayey soil specimen subjected to macroscopic loading are examined using a medi- cal-use computerized tomography (CT) instrument. Disturbed state concept (DSC) theory is based on the utilization of the hard- ening model. DSC indirectly describes material behavior by claiming that the actual response of the material is expressed in terms of the relative intact (RI) response and the fully adjusted (FA) response. The occurrence of mesoscopic structural changes of material has similarities with the occurrence of a macroscopic response of the material under loadings. In general, the relative changing value of a softening material is three to five times more than that of a hardening material. Whether special zones exist or not in a specimen cross section does not affect the following conclusion: hardening material and softening material show me- chanical differences with CT statistical indices values prominently changing, and the change is related to the superposing of a disturbance factor. A new disturbance factor evolution function is proposed. Thus, mesoscopic statistical indices are introduced to describe macroscopic behavior through the new evolution function. An application of the new evolution function proves the effectiveness of the amalgamation of a macroscopic and a mesoscopic experimental phenomenon measurement methods.

关键词： Constitutive model Disturbed state concept (DSC) Computerized tomography (CT) softening

Accelerated flow softening and dynamic transformation of Ti-6Al-4V alloy in two-phase region during hot deformation via coarsening αgrain

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Journal of Materials Science & Technology 2020年第1期36卷 160-166页

作者： Xiankun Ji Baoqi Guo Fulin Jiang Hong Yu Dingfa Fu Jie Teng Hui Zhang John J.Jonas College of Materials Science and Engineering Hunan UniversityChangsha 410082China Materials Engineering McGill University3610 University St.Montreal H3A 0C5Canada

The flow softening is an important phenomenon during hot deformation of metallic *** the present work,a more evident flow softening of Ti-6 Al-4 V alloy when deformed in two-phase region was observed in coarser a grain sample,which was attributed to an accelerated dynamic transformation from harder α phase into β ***,full β microstructure was observed in coarse grain samples at strain of 1.2,while retained a phase was observed in fine a grain *** the views of thermodynamics and crystallographic analysis,the in-depth mechanisms of dynamic transformation were further investigated.

关键词： Titanium alloys Hot deformation Flow softening Dynamic transformation Grain size

Transition from source-to stress-controlled plasticity in nanotwinned materials below a softening temperature

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npj Computational Materials 2019年第1期5卷 1105-1111页

作者： Seyedeh Mohadeseh Taheri Mousavi Haofei Zhou Guijin Zou Huajian Gao School of Engineering Brown UniversityProvidenceRI 02912USA Department of Materials Science and Engineering Massachusetts Institute of Technology77 Massachusetts AvenueCambridgeMA 02139USA

Nanotwinned materials have been widely studied as a promising class of nanostructured materials that exhibit an exceptional combination of high strength,good ductility,large fracture toughness,remarkable fatigue resistance,and creep ***,an apparent controversy has emerged with respect to how the strength of nanotwinned materials varies as the twin thickness is *** a transition from hardening to softening was observed in nanotwinned Cu when the twin thickness is reduced below a critical value,continuous hardening was reported in nanotwinned ceramics and nanotwinned ***,by conducting atomistic simulations and developing a theoretical modeling of nanotwinned Pd and Cu systems,we discovered that there exists a softening temperature,below which the material hardens continuously as the twin thickness is reduced(as in nanotwinned ceramics and diamond),while above which the strength first increases and then decreases,exhibiting a maximum strength and a hardening to softening transition at a critical twin thickness(as in nanotwinned Cu).This important phenomenon has been attributed to a transition from source-to stress-controlled plasticity below the softening temperature,and suggests that different hardening behaviors may exist even in the same nanotwinned material depending on the temperature and that at a given temperature,different materials could exhibit different hardening behaviors depending on their softening temperature.

关键词： softening stress creep

Warm deformation behavior and work-softening mechanism of Fe- 6.5wt.%Si alloy

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Journal of Iron and Steel Research International 2020年第3期27卷 342-354页

作者： Xiang-ju Shi Yong-feng Liang Bin-bin Liu Bao Zhang Feng Ye State Key Laboratory for Advanced Metals and Materials University of Science and Technology BeijingBeijing 100083China

Warm deformation behavior of the Fe-6.5wt.%Si alloy was studied by isothermal compression in the temperature range of 300-700℃.The results show that the influence of the ordered phases on the flow stress gradually weakens with increasing deformation *** flow stress of the furnace-cooled sample with the high degree of order at 300℃is higher than that of the quenched sample with the low degree of order,and the flow stresses of both samples are nearly the same at 500-700℃.The hardness difference between two samples deformed at 500℃gradually decreases with increasing strain,accompanying with a reduction in hardness of the furnace-cooled sample,which indicates a work-softening *** analyses of dislocation configurations and ordered structure suggest that the dynamic recovery and deformation-induced disorder result in the work-softening *** appropriate deformation temperature window for improving the formability of the Fe-6.5wt.%Si alloy is about 500-600℃.

关键词： Fe-6.5wt.%Si alloy Work softening Ordered structure Dynamic recovery Anti-phase boundary Dislocation

Study on the damage-softening constitutive model of rock and experimental verification

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Acta Mechanica Sinica 2019年第4期35卷 786-798页

作者： Sheng-Qi Yang Bo Hu Peng Xu State Key Laboratory for Geomechanics and Deep Underground Engineering School of Mechanics and Civil Engineering China University of Mining and Technology Xuzhou 221116 China China Construction Third Engineering Design Bureau Co. Ltd Wuhan 430064 China

A damage-softening model is presented to describe the stress-strain curve of rock. By comparing the Hoek-Brown (H-B) and Mohr-Coulomb (M-C) yield criterion, the equivalent M-C yield criterion is selected as the strength criterion in this model. To better characterize the rock damage and failure processes with considering the relationship between damage and deformation, the concept of yield stress ratio is introduced to describe the yield strengthening deformation before rock peak stress. Damage events are described by two cumulative damage evolution laws. The evolution equations of tensile and shear damage are presented based on the equivalent plastic strains and the maximum value between tensile and shear damage represents the total damage for rock. Considering that rock cannot bear tensile load after tensile failure but still has a certain shear strength, its tensile and shear strengths are small after shear failure. The elastic modulus is affected by tensile damage, whereas the angle of internal friction, the cohesion, and dilation angles are influenced by shear damage. The proposed damage-softening model describes the strain-softening, brittle stress-drop, and residual strength of rock after peak stress, and finally the model is implemented in FLAC3D. Comparing the test and the numerical calculation results, the damage-softening model better describes the total stress-strain curve of rock.

关键词： Rock deformation Damage evolution softening Numerical calculation