In this study,the effect of decarburization annealing temperature and time on the carbon content,microstructure,and texture of grain-oriented pure iron was investigated by optical microscopy and scanning electron micr...In this study,the effect of decarburization annealing temperature and time on the carbon content,microstructure,and texture of grain-oriented pure iron was investigated by optical microscopy and scanning electron microscopy with electron-backscatter diffraction. The results showed that the efficiency of decarburization dramatically increased with increasing decarburization temperature. However,when the annealing temperature was increased to 825°C and 850°C,the steel's carbon content remained essentially unchanged at 0.002%. With increasing decarburization time,the steel's carbon content generally decreased. When both the decarburization temperature and time were increased further,the average grain size dramatically increased and the number of fine grains decreased; meanwhile,some relatively larger grains developed. The main texture types of the decarburized sheets were approximately the same: {001}<110> and {112~115}<110>,with a γ-fiber texture. Furthermore,little change was observed in the texture. Compared with the experimental sheets,the texture of the cold-rolled sheet was very scattered. The best average magnetic induction(B_(800)) among the final products was 1.946 T.展开更多
To promote the manufacture of grain-oriented pure iron, the texture and inhibitor features of two samples A and B produced by different cold-rolling processes were studied by optical microscopy, X-ray diffraction, and...To promote the manufacture of grain-oriented pure iron, the texture and inhibitor features of two samples A and B produced by different cold-rolling processes were studied by optical microscopy, X-ray diffraction, and transmission electron microscopy. The results showed that a higher content of inhibitor elements directly resulted in a greater number of fine inhibitors, which exhibited strong inhibitory ability, leading to more fine precipitates of appropriate size effectively inhibiting the growth of primary grains in decarburized bands （sheets） during the single-stage cold-rolling process. The formation of the component with { 110}〈001〉 Goss orientation was greatly suppressed in the stage of primary recrystallization, and this component could hardly be observed in the decarburized band; by contrast, the {411 }〈148〉-oriented grains grew. During the process of high-temperature annealing, abnormal growth occurred and secondary recrystallized grains （Goss orientation） merged with other matrix grains such as { 111 }〈112〉 and {411 }〈148〉. The magnetic induction of samples A and B at 800 Aim was 1.939 T and 1.996 T, respectively.展开更多
The structure of ultrafine grain is formed at the crater bottom of pure iron target under hypervelocity impact. The microstructures of different layers at the crater bottom were characterized by optical microscopy （O...The structure of ultrafine grain is formed at the crater bottom of pure iron target under hypervelocity impact. The microstructures of different layers at the crater bottom were characterized by optical microscopy （OM）, scanning electron microscopy （SEM） and transmission electron microscopy （TEM）. The cross-section observation was performed to reveal the grain refinement process driven by plastic deformation. Firstly, low energy dislocation structures （LEDS） such as dense dislocation walls （DDWs） and dislocation tangles （DTs） refine the original grains and form intersecting lamellar structures. With increasing strain, DDWs and DTs transform into subboundaries with small misorientations to separate lamellar structure to cells. Subboundaries are converted to high misorientation grain boundaries, so ultrafine grains are formed. The formation of ultrafine grains was discussed in the dynamic recrystallization process due to the large strain and strain rate induced by spherical shock wave.展开更多
This paper provides an investigation of the phase transition and spalling characteristic induced during shock loading and unloading in the pure iron and the FeMnNi alloy. The impact for the pure iron is symmetric and ...This paper provides an investigation of the phase transition and spalling characteristic induced during shock loading and unloading in the pure iron and the FeMnNi alloy. The impact for the pure iron is symmetric and with the same-thickness for both the flyer and the target plate. It is found that an abnormal multiple spalling happens in the pure iron sample as the pressure exceeds the α- ε transition threshold of 13 GPa. In the symmetric and same-thickness impact and reverse impact experiments of the FeMnNi alloy, two abnormal tension regions occur when the pressure exceeds the α - ε transition threshold of 6.3 GPa, and the reverse phase transition s - ~ begins below 4.2 GP. The experimental process is simulated successfully from the non-equilibrium mixture phase and Boettger＇s model. Such abnormal spalling phenomena are believed to relate to the shocked α - ε phase transition. The possible reasons for the abnormal multiple spalling, which occurs during the symmetric and same-thickness impact experiments of pure iron and FeMnNi alloy, are discussed.展开更多
The phenomenon of stress-induced recrystallization (SIR) and recrystallization- induced plasticity (RIP) in DT4 pure iron was investigated by means of hightemperature tensile test under a constant elastic stress and ...The phenomenon of stress-induced recrystallization (SIR) and recrystallization- induced plasticity (RIP) in DT4 pure iron was investigated by means of hightemperature tensile test under a constant elastic stress and microstructural observation. It is shown that the macroscopic plastic flow of cold-rolled specimens, which occured during heating process under pre-loaded elastic stress, resulted from stressinduced recrystallization and recrystallization-induced plasticity. The characteristics and mechanism of this phenomenon were also preliminarily discussed.展开更多
Pure iron is one of the difficult-to-machine materials due to its large chip deformation,adhesion,work-hardening,and built-up edges formation during machining.This leads to a large workpiece deformation and challenge ...Pure iron is one of the difficult-to-machine materials due to its large chip deformation,adhesion,work-hardening,and built-up edges formation during machining.This leads to a large workpiece deformation and challenge to meet the required technical indicators.Therefore,under varying the grain size of pure iron,the influence of cutting speed,feed,and depth of cut on the cutting force,heat generation,and machining residual stresses were explored in the turning process to improve the machinability without compromising the mechanical properties of the material.The experimental findings have depicted that the influence of grain size on cutting force in the precision turning process is not apparent.However,the cutting temperature and residual stress of machining fine-grain iron were much smaller than the coarse grain at all levels of cutting parameters.展开更多
In the present study, pure iron/copper composite metal cladding was deposited onto carbon steel by tungsten inert gas welding. The study focused on interfacial morphological, microstructural, and mechanical analyses o...In the present study, pure iron/copper composite metal cladding was deposited onto carbon steel by tungsten inert gas welding. The study focused on interfacial morphological, microstructural, and mechanical analyses of the composite cladding layers. Iron liquid–solid-phase zones were formed at copper/steel and iron interfaces because of the melting of the steel substrate and iron. Iron concentrated in the copper cladding layer was observed to exhibit belt, globule, and dendrite morphologies. The appearance of iron-rich globules indicated the occurrence of liquid phase separation（LPS） prior to solidification, and iron-rich dendrites crystallized without the occurrence of LPS. The maximum microhardness of the iron/steel interface was lower than that of the copper/steel interface because of the diffusion of elemental carbon. All samples fractured in the cladding layers. Because of a relatively lower strength of the copper layer, a short plateau region appeared when shear movement was from copper to iron.展开更多
The samples of pure Fe were treated by surface gas phase RE permeation plus laser melting solidification (LMS). The microstructures were observed by Scanning Electron Microscope (SEM) and X ray Photoelectron Spectro...The samples of pure Fe were treated by surface gas phase RE permeation plus laser melting solidification (LMS). The microstructures were observed by Scanning Electron Microscope (SEM) and X ray Photoelectron Spectroscopy (XPS), meanwhile the corrosion resistance was investigated by electrochemical impedance spectroscopy (EIS) and anodic polarization. The results show that this treatment can remarkably improve the density and uniformity of microstructure, and enhance corrosion resistance of the pure Fe surface.展开更多
This study explores reasons for the random occurrence of stamping cracks during the production of pure iron magnetic shielding covers. Scanning electron microscopy and energy spectrum are used to observe cracks within...This study explores reasons for the random occurrence of stamping cracks during the production of pure iron magnetic shielding covers. Scanning electron microscopy and energy spectrum are used to observe cracks within parts, and results show significant brittle fracture morphology with chunks of manganese silicate and aluminum silicate inclusions present in the fracture surface. The chemical composition, mechanical properties, and microstructure are also analyzed for a corresponding batch of cold rolled pure iron sheet. The oxygen content of the material is found to be high,resulting in the random distribution of a large amount of long chain manganese silicate and aluminum silicate inclusions along the rolling direction, which corresponds to inclusions found on the fractured surface. The stamping cracks are thus assumed to be caused by the randomly distributed chain of inclusions within the cold rolled sheet. It is suggested that the amount of deoxidizer used should be more carefully controlled to decrease the inclusion contents and to thus avoid the recun＇ence of such defects.展开更多
The liquid structure of pure iron at 1540, 1560 and 1580 deg C was studied byX-ray diffraction. The results show that near the melting point there is a medium-range orderstructure that fades away with the increasing t...The liquid structure of pure iron at 1540, 1560 and 1580 deg C was studied byX-ray diffraction. The results show that near the melting point there is a medium-range orderstructure that fades away with the increasing temperature. The average nearest distance of atoms isalmost independent of the melts temperature, but the average coordination number, the atom clustersize and the atom number in an atom cluster all decrease with the increasing temperature of themelt. Near the melting point there are a lot of atom clusters in the pure iron melt. The atomcluster of pure iron has the body-centered cubic lattices, which are kept from the solid state. Andthe body-centered cubic lattices connect into network by occupying a same edge. The atoms in thesurrounding of the atom clusters are arranged disorderly.展开更多
文摘In this study,the effect of decarburization annealing temperature and time on the carbon content,microstructure,and texture of grain-oriented pure iron was investigated by optical microscopy and scanning electron microscopy with electron-backscatter diffraction. The results showed that the efficiency of decarburization dramatically increased with increasing decarburization temperature. However,when the annealing temperature was increased to 825°C and 850°C,the steel's carbon content remained essentially unchanged at 0.002%. With increasing decarburization time,the steel's carbon content generally decreased. When both the decarburization temperature and time were increased further,the average grain size dramatically increased and the number of fine grains decreased; meanwhile,some relatively larger grains developed. The main texture types of the decarburized sheets were approximately the same: {001}<110> and {112~115}<110>,with a γ-fiber texture. Furthermore,little change was observed in the texture. Compared with the experimental sheets,the texture of the cold-rolled sheet was very scattered. The best average magnetic induction(B_(800)) among the final products was 1.946 T.
基金This work was financially supported by the National Natural Science Foundation of China （No. 51804003）.
文摘To promote the manufacture of grain-oriented pure iron, the texture and inhibitor features of two samples A and B produced by different cold-rolling processes were studied by optical microscopy, X-ray diffraction, and transmission electron microscopy. The results showed that a higher content of inhibitor elements directly resulted in a greater number of fine inhibitors, which exhibited strong inhibitory ability, leading to more fine precipitates of appropriate size effectively inhibiting the growth of primary grains in decarburized bands （sheets） during the single-stage cold-rolling process. The formation of the component with { 110}〈001〉 Goss orientation was greatly suppressed in the stage of primary recrystallization, and this component could hardly be observed in the decarburized band; by contrast, the {411 }〈148〉-oriented grains grew. During the process of high-temperature annealing, abnormal growth occurred and secondary recrystallized grains （Goss orientation） merged with other matrix grains such as { 111 }〈112〉 and {411 }〈148〉. The magnetic induction of samples A and B at 800 Aim was 1.939 T and 1.996 T, respectively.
文摘The structure of ultrafine grain is formed at the crater bottom of pure iron target under hypervelocity impact. The microstructures of different layers at the crater bottom were characterized by optical microscopy （OM）, scanning electron microscopy （SEM） and transmission electron microscopy （TEM）. The cross-section observation was performed to reveal the grain refinement process driven by plastic deformation. Firstly, low energy dislocation structures （LEDS） such as dense dislocation walls （DDWs） and dislocation tangles （DTs） refine the original grains and form intersecting lamellar structures. With increasing strain, DDWs and DTs transform into subboundaries with small misorientations to separate lamellar structure to cells. Subboundaries are converted to high misorientation grain boundaries, so ultrafine grains are formed. The formation of ultrafine grains was discussed in the dynamic recrystallization process due to the large strain and strain rate induced by spherical shock wave.
基金Project supported by the National Science Foundations of China (Grant Nos. 10776032 and 10902102)Science Foundation of China Academy of Engineering Physics (Grant Nos. 20060104 and 2009B0201014)
文摘This paper provides an investigation of the phase transition and spalling characteristic induced during shock loading and unloading in the pure iron and the FeMnNi alloy. The impact for the pure iron is symmetric and with the same-thickness for both the flyer and the target plate. It is found that an abnormal multiple spalling happens in the pure iron sample as the pressure exceeds the α- ε transition threshold of 13 GPa. In the symmetric and same-thickness impact and reverse impact experiments of the FeMnNi alloy, two abnormal tension regions occur when the pressure exceeds the α - ε transition threshold of 6.3 GPa, and the reverse phase transition s - ~ begins below 4.2 GP. The experimental process is simulated successfully from the non-equilibrium mixture phase and Boettger＇s model. Such abnormal spalling phenomena are believed to relate to the shocked α - ε phase transition. The possible reasons for the abnormal multiple spalling, which occurs during the symmetric and same-thickness impact experiments of pure iron and FeMnNi alloy, are discussed.
文摘The phenomenon of stress-induced recrystallization (SIR) and recrystallization- induced plasticity (RIP) in DT4 pure iron was investigated by means of hightemperature tensile test under a constant elastic stress and microstructural observation. It is shown that the macroscopic plastic flow of cold-rolled specimens, which occured during heating process under pre-loaded elastic stress, resulted from stressinduced recrystallization and recrystallization-induced plasticity. The characteristics and mechanism of this phenomenon were also preliminarily discussed.
基金National Defense Foundation Pre-Research Science Challenge Project(Grant No.JCKY2016212A506-0107)Development Funds of China Academy of Engineering Physics(Grant No.2015B0203029).
文摘Pure iron is one of the difficult-to-machine materials due to its large chip deformation,adhesion,work-hardening,and built-up edges formation during machining.This leads to a large workpiece deformation and challenge to meet the required technical indicators.Therefore,under varying the grain size of pure iron,the influence of cutting speed,feed,and depth of cut on the cutting force,heat generation,and machining residual stresses were explored in the turning process to improve the machinability without compromising the mechanical properties of the material.The experimental findings have depicted that the influence of grain size on cutting force in the precision turning process is not apparent.However,the cutting temperature and residual stress of machining fine-grain iron were much smaller than the coarse grain at all levels of cutting parameters.
基金financially supported by the National Natural Science Foundation of China (No. 51575132)
文摘In the present study, pure iron/copper composite metal cladding was deposited onto carbon steel by tungsten inert gas welding. The study focused on interfacial morphological, microstructural, and mechanical analyses of the composite cladding layers. Iron liquid–solid-phase zones were formed at copper/steel and iron interfaces because of the melting of the steel substrate and iron. Iron concentrated in the copper cladding layer was observed to exhibit belt, globule, and dendrite morphologies. The appearance of iron-rich globules indicated the occurrence of liquid phase separation（LPS） prior to solidification, and iron-rich dendrites crystallized without the occurrence of LPS. The maximum microhardness of the iron/steel interface was lower than that of the copper/steel interface because of the diffusion of elemental carbon. All samples fractured in the cladding layers. Because of a relatively lower strength of the copper layer, a short plateau region appeared when shear movement was from copper to iron.
文摘The samples of pure Fe were treated by surface gas phase RE permeation plus laser melting solidification (LMS). The microstructures were observed by Scanning Electron Microscope (SEM) and X ray Photoelectron Spectroscopy (XPS), meanwhile the corrosion resistance was investigated by electrochemical impedance spectroscopy (EIS) and anodic polarization. The results show that this treatment can remarkably improve the density and uniformity of microstructure, and enhance corrosion resistance of the pure Fe surface.
文摘This study explores reasons for the random occurrence of stamping cracks during the production of pure iron magnetic shielding covers. Scanning electron microscopy and energy spectrum are used to observe cracks within parts, and results show significant brittle fracture morphology with chunks of manganese silicate and aluminum silicate inclusions present in the fracture surface. The chemical composition, mechanical properties, and microstructure are also analyzed for a corresponding batch of cold rolled pure iron sheet. The oxygen content of the material is found to be high,resulting in the random distribution of a large amount of long chain manganese silicate and aluminum silicate inclusions along the rolling direction, which corresponds to inclusions found on the fractured surface. The stamping cracks are thus assumed to be caused by the randomly distributed chain of inclusions within the cold rolled sheet. It is suggested that the amount of deoxidizer used should be more carefully controlled to decrease the inclusion contents and to thus avoid the recun＇ence of such defects.
基金This work was financially supported by the National Natural Science Foundation of China (No.59974003)"973" Research Foundation of the Science and Technology Ministry of China (No. G199806150402)
文摘The liquid structure of pure iron at 1540, 1560 and 1580 deg C was studied byX-ray diffraction. The results show that near the melting point there is a medium-range orderstructure that fades away with the increasing temperature. The average nearest distance of atoms isalmost independent of the melts temperature, but the average coordination number, the atom clustersize and the atom number in an atom cluster all decrease with the increasing temperature of themelt. Near the melting point there are a lot of atom clusters in the pure iron melt. The atomcluster of pure iron has the body-centered cubic lattices, which are kept from the solid state. Andthe body-centered cubic lattices connect into network by occupying a same edge. The atoms in thesurrounding of the atom clusters are arranged disorderly.
