Over the years,the high magnetic induction of industrial Mn-added electrical steel is assumed to be the enhancement of{100}texture derived from its austenite-ferrite phase transformation during hot rolling(phase trans...Over the years,the high magnetic induction of industrial Mn-added electrical steel is assumed to be the enhancement of{100}texture derived from its austenite-ferrite phase transformation during hot rolling(phase transformation(PT)method).However,it is still undetermined without straightforward experimental evidence.The reason for{100}texture improvement of Mn-added electrical steel is experimentally confirmed due to the recrystallization induced by the austenite-ferrite phase transformation during hot rolling.Moreover,a more promising methodology to further improve{100}texture and formability of hot-rolled electrical steel is promoted by the control of hot rolling deformation condition(shear deformation(SD)method).The results show that the nucleation mechanisms of{100}oriented recrystallized grains are different in the samples by SD and PT methods,which are in-depth shear deformation and austenite-ferrite phase transformation,respectively.In this case,coarse{100}oriented recrystallized grains and low residual stress are obtained in the sample by SD method,which is responsible for its superior{100}texture and formability.In contrast,the sample by PT method forms fine recrystallized grains with random orientations and accumulates severe residual stress.展开更多
The effect of lanthanum on the characteristics of inclusions in the slab of non-oriented electrical steels was investigated through industrial trials and thermodynamic analysis.The number,size,and chemical composition...The effect of lanthanum on the characteristics of inclusions in the slab of non-oriented electrical steels was investigated through industrial trials and thermodynamic analysis.The number,size,and chemical composition of inclusions in the surface,one-quarter of thickness and the center of slabs with and without lanthanum addition were statistically analyzed using an automatic inclusion analysis system.In the lanthanum-free slab,inclusions were predominately MgO.Al_(2)O_(3),MgO,and AlN as well as a small number of Al_(2)O_(3)-MgO-CaO and MgS.The number densities of oxide inclusions and AlN decreased from the surface to the center of the slab,which was ascribed to the difference in cooling intensity during the continuous casting.In the steel with lanthanum addition,inclusions were modified into LaAlO_(3) and La_(2)O_(2)S and gradually transformed into dual-phase MgO-La_(2)S3 with an increasing distance from the slab surface due to the reaction between the lanthanum-containing inclusion and the steel matrix.The uneven distribution of oxide inclusions along the thickness of the slab was eliminated in the lanthanum-bearing slab because the dissolved oxygen was remarkably decreased by lanthanum.Lanthanum-bearing inclusions were more likely to agglomerate AlN by inducing the heterogeneous nucleation of AlN on their surface,while small-size MgO.Al_(2)O_(3) inclusions hardly showed a coarsening effect on the size of AlN.展开更多
High performance e-motors require a continuous enhancement of physical and mechanical properties for non-oriented electrical steel(NOES).However,the optimization of mechanical and magnetic properties simultaneously du...High performance e-motors require a continuous enhancement of physical and mechanical properties for non-oriented electrical steel(NOES).However,the optimization of mechanical and magnetic properties simultaneously during NOES processing is extremely challenging where both properties directly influenced by alloy grain size,crystallographic texture,and dislocation density.In the current investigation,recrystallization annealing cycles were employed to modify the microstructure with the aim of balance magnetic and mechanical properties of NOES concurrently.The results showed that with increasing annealing temperatures,the degree of recrystallization and grain size increased,while the dislocation density reduced considerably at the early stage of recrystallization.Meanwhile,the values of texture parameter A*_(overall)(which is a function of overall individual grain orientations and their alignments with easy magnetization directions)were increased.It was evident that the magnetic properties were significantly improved,however the alloy strength was reduced with increasing annealing temperatures.Here,the correlation between magnetic properties as well as alloy strength on grain size,texture,and dislocation density were determined.From crystallographic texture intensity and measured properties quantitative analyses it was concluded that grain size was the predominant factor in balancing the mechanical and magnetic properties of the studied steel.Furthermore,the optimal comprehensive properties(both magnetic and mechanical)were achieved by annealing at 800℃,which yielded a magnetic induction B5000 of 1.616 T,a high-frequency iron loss P_(1.0/400)of 22.43 W/kg,and a yield strength of 527 MPa.展开更多
Sub-rapid solidification has the potential to enhance the columnar structure and the magnetic property of electrical steels.However,research on the hot deformation behavior of sub-rapid solidified non-oriented electri...Sub-rapid solidification has the potential to enhance the columnar structure and the magnetic property of electrical steels.However,research on the hot deformation behavior of sub-rapid solidified non-oriented electrical steel,particularly at varying strain rates,has yet to be fully understood.The effect of thermal compression on the microstructure and mechanical properties of 3.15 wt.%Si non-oriented electrical steel strips produced through a strip casting simulator was systematically investigated.The findings reveal that increasing the deformation temperature enhances grain recrystallization,while the peak stress decreases with higher temperature.Furthermore,a lower strain rate favors dynamic recrystallization and reduces thermal stress.It can be seen that sub-rapid solidification can effectively reduce the thermal activation energy of non-oriented electrical steel,and the thermal activation energy is calculated to be 204.411 kJ/mol.In addition,the kinetic models for the dynamic recrystallization volume fraction of the studied 3.15 wt.%Si non-oriented electrical steel were established.展开更多
The evolution of microstructure,texture,and magnetic properties with random texture,near-copper texture,weak near-cube texture,and strong λ fiber(<001>/ND(normal direction))before rolling of non-oriented electr...The evolution of microstructure,texture,and magnetic properties with random texture,near-copper texture,weak near-cube texture,and strong λ fiber(<001>/ND(normal direction))before rolling of non-oriented electrical steel was studied.Three recrystallized hot bands with different textures but similar grain sizes were prepared by pre-annealing at low-temperature and high-temperature normalization annealing.It was observed that the final annealed products exhibited similar recrystallized microstructures.By contrast,the final annealed product with more 2 fiber before rolling exhibited a stronger cube texture.With the fiber before rolling becoming stronger,the proportion of(111)<110>deformed matrices became larger,which could be observed in the early recrystallization stage.The overwhelmingly dominant 2 orientation nuclei are formed in the(111)<110>deformed matrix and become the dominant texture.Eventually,the best magnetic properties are obtained in the products with strong 2 fiber before rolling,corresponding to the strong cube texture and low anisotropyparameter.展开更多
The effect of lanthanum content in the range of 04）.01 1 wt.%, on the inclusion size distribution, microstructure, texture and magnetic properties of three non-oriented electrical steels was studied. After final anne...The effect of lanthanum content in the range of 04）.01 1 wt.%, on the inclusion size distribution, microstructure, texture and magnetic properties of three non-oriented electrical steels was studied. After final annealing, lanthanum effectively inhibited the precipitation of MnS precipitates in steel, the formations of La2O2S and LaS inclusions not only acted as nuclei of AlN precipitates, but also combined with A1203 and formed composite inclusions with larger size. Grain size firstly increased and then decreased with lanthanum content increasing. Steel containing 0.0066 wt.% lanthanum obtained the largest grain size, the strongest { 110} 〈 110〉 texture and the weakest { 112}〈110〉 texture among all the tested steels. Magnetic flux density firstly increased and then decreased, core loss firstly dramatically decreased and then slightly decreased with lanthanum content increasing. Among the three tested steels, steel with 0.0066 wt.% lanthanum demonstrated the best comprehensive magnetic properties mainly through the development of favorable texture and appropriate final grain size.展开更多
The effects of Sn addition on core loss and texture of non-oriented electrical steels were investigated. Experiments revealed that the core loss of non-oriented electrical steels could be obviously decreased and the i...The effects of Sn addition on core loss and texture of non-oriented electrical steels were investigated. Experiments revealed that the core loss of non-oriented electrical steels could be obviously decreased and the intensity of {111 } texture and { 112} texture of final annealed specimens could be markedly reduced by Sn addition. The reasons for reducing core loss and the intensity of unfavorable texture were analyzed.展开更多
Combining with the study of analogue experiments and test analysis, the kinetics of precipitation and growth of AlN and MnS in non-oriented electrical steel produced by the CSP process is calculated. The results show ...Combining with the study of analogue experiments and test analysis, the kinetics of precipitation and growth of AlN and MnS in non-oriented electrical steel produced by the CSP process is calculated. The results show that the precipitate phase particles of AlN and MnS in typical non-oriented electrical steel grades produced by the CSP process have grown to some extent in the soaking stage, but the precipitation contents are less than 20% of the total contents of nitride and sulfide. The precipitate phase particles of AlN and MnS have precipitated almost after the hot rolling process. The precipitation contents are more than 80% of the total contents of nitride and sulfide, but it is very late for the precipitate phase particles to grow at the end of the hot rolling process.展开更多
The effects of heating rate （ranging from 50 to 300 ℃/s） during the final annealing process on microstructure evolution and magnetic properties of cold rolled non-oriented electrical steel were investigated. It was...The effects of heating rate （ranging from 50 to 300 ℃/s） during the final annealing process on microstructure evolution and magnetic properties of cold rolled non-oriented electrical steel were investigated. It was found that increasing heating rate increased the nucleation temperature and complete recrystallization temperature. At the same time, heating rate increasing could cause the substantially refined structures for the recrystallization grains and this grain refinement would decline when the heating rate was beyond 50 ℃/s. The recrystallization texture exhibited pronounced improvement with heating rate, such as the intensity decrease of 〈111〉//ND （normal direction） fiber and the intensity increase of { 110}%〈001〉 Goss texture component. The texture improvement and grain size refinement caused by heating rate increasing resulted in complicated variation of the magnetic properties. The magnetic induction （B50） keeps increasing while heating rate increases from 15 to 300 ℃/s which is due to the recrystallized texture optimization caused by rapid heating. The core losses （P1.5/50） decrease while heating rate increases from 15 to 100 ℃/s; however, the core losses would increase when heating rate is higher than 100 ℃/s, which is caused by the mean grain size refinement after rapid heating annealing. The results indicate that recrystallization texture and the magnetic properties of the non-oriented electrical steel can be improved definitely by rapid heating during the final annealing treatment.展开更多
High-grade non-oriented silicon steel with higher permeability and lower core loss has become the pursed target with the rapid developnient of electrical machines.The effects of rare-earth(RE)element on recrystallizat...High-grade non-oriented silicon steel with higher permeability and lower core loss has become the pursed target with the rapid developnient of electrical machines.The effects of rare-earth(RE)element on recrystallization texture in RE-doped Fe-3.1 wt.%Si-1.2 wt.%Al non-oriented silicon steel were investigated by macro-and micro-texture analyses.Nonlinear variation of recrystallization texture with RE element content was observed.In the competition among main recrystallization texture components,favorable{113}<361>and X fiber(<001>//ND)are strengthened and unfavorable y fiber is evidently decreased by the addition of RE element,whereas the effect of RE element is reversed by excess RE element.The recrystallization texture development is determined by RE-affected nucleation and grain growth in terms of grain boundary migration related to segregation and inclusion.The properly inhibited grain boundary mobility can promote favorable recrystallization texture by the improved nucleation and efficient grain growth.展开更多
Non-oriented silicon steels containing different mass fractions of lanthanum were prepared using a high-frequency suspended furnace.Microstructures were observed by a metallographic microscope and micro-orientations w...Non-oriented silicon steels containing different mass fractions of lanthanum were prepared using a high-frequency suspended furnace.Microstructures were observed by a metallographic microscope and micro-orientations were analyzed by a scanning electron microscope（SEM）.The results showed that at the annealing temperature of 870℃,recrystallization started at 90 s and completed at 120 s during annealing.Without lanthanum,no matter Cube or {111 }110 grains,recrystallized grains nucleated mainly in deformed {111}110 and {113}031 grains.With lanthanum,however,they nucleated in the deformed {110} and {112}132grains.This indicated that addition of lanthanum changed the micro-orientation relationship between new grains and the matrix.展开更多
Thin-gauge non-oriented electrical steel sheets of 0.2 mm in thickness with high magnetic induction and low core loss were produced by a two-stage cold-rolling method with and without normalization annealing.The throu...Thin-gauge non-oriented electrical steel sheets of 0.2 mm in thickness with high magnetic induction and low core loss were produced by a two-stage cold-rolling method with and without normalization annealing.The through-process texture evolutions of the two processes were compared and studied by means of X-ray diffractometer and electron backscattered diffraction.Results showed that excellent magnetic properties were attributed to strong η-fiber recrystallization texture in the final sheet.Coarse γ-fiber-oriented grains after intermediate annealing and medium cold-rolling reduction were considered key factors to obtain a strong γ-fiber texture given that a large number of shear bands within the γ-fiber deformed matrix provided dominant nucleation sites for η-fiber-oriented grains.The normalization annealing after hot rolling was favorable for the retention of cube texture,thereby decreasing the magnetic anisotropy of thin-gauge non-oriented electrical steels.展开更多
In this study, two types of as-cast microstructure produced by strip casting were cold rolled and annealed to investigate the effect of initial microstructure on the textural evolution and magnetic properties of non-o...In this study, two types of as-cast microstructure produced by strip casting were cold rolled and annealed to investigate the effect of initial microstructure on the textural evolution and magnetic properties of non-oriented silicon steel. The results indicated that the cold-rolled sheets of coarse-grained strip with pronounced {100} components exhibited stronger 入 fiber(<100>//ND) and weaker γ fiber(<111>//ND)texture as composed to the fine-grained strip with strong Goss({110}(001)) texture. After annealing, the former was dominated by η fiber(<001>//RD) texture with a peak at {110}<001)orientation, while the latter consisted of strong {111}(112) and relatively weak {110}(001) texture. In addition, a number of precipitates of size ～30-150 nm restricted the grain growth during annealing, resulting in recrystallization of grain size of ～46 μm in the coarse-grained specimen and ～41μm in the fine-grained specimen.Ultimately, higher magnetic induction(～1.72 T) and lower core loss(～4.04 W/kg) were obtained in the final annealed sheets of coarse-grained strip with strong {100} texture.展开更多
Aluminum nitride （AIN） precipitates and microstructure of 4 wt.% （Si＋AI） non-oriented electrical steel were investigated. The 2.0 mm thick cast strips with three different silicon/aluminum （Si/AI） ratios were p...Aluminum nitride （AIN） precipitates and microstructure of 4 wt.% （Si＋AI） non-oriented electrical steel were investigated. The 2.0 mm thick cast strips with three different silicon/aluminum （Si/AI） ratios were produced by twin-roll casting process, then the strips were reheated, warm rolled, cold rolled and annealed. The microstructure and AIN precipitates were characterized using optical microscopy, scanning electron microscopy and transmission electron microscopy. The results showed that with the increase of Si/AI ratio, on the one hand, the casting microstructure changed from columnar grains to equiaxed grains, and the uniformity of annealed microstructure was improved; On the other hand, the number of AIN precipitates in cast strips reduced meanwhile the distribution became dispersed. By the reheat treatment, the size and distribution of the AIN precipitates can be changed. Moreover, the grain size of the annealed strips is in the range of 20-50 #m, at the same time, many AIN precipitates were located at grain boundaries. Therefore, controlling the Si/AI ratio is a simple method to obtain desired microstructure. Then AIN precipitates in non-oriented electrical steel prepared by twin-roll casting process hinder markedly the recrystallized grains growth, A compatible reheat treatment can be an approach worth exploring to control the behavior of AIN precipitates.展开更多
The effects of boron content in the range of 0-0.0082 wt%, on the inclusion type, microstructurc, texture and magnetic properties of non-oriented electrical steels have been studied. After final annealing, the additio...The effects of boron content in the range of 0-0.0082 wt%, on the inclusion type, microstructurc, texture and magnetic properties of non-oriented electrical steels have been studied. After final annealing, the addition of excess boron（w（B0〉0.004 1 wt%） led to the formation of Fe2B particles. As boron content increased, grain size increased and reached a maximum in steel with 0.004 1 wt% boron. Furthermore, steel containing 0.004 1 wt% boron had the strongest { 100} fiber texture, Goss texture and the weakest { 111 } fiber texture among the five tested steels. Flux density firstly rapidly increased and then suddenly decreased with increasing boron content and reached a maximum in steel with 0.004 1 wt% boron. Conversely, core loss first sharply decreased and then abruptly increased with the increase of boron content and reached a minimum in steel containing 0.004 1 wt% boron. Steel containing 0.004 1 wt% boron obtained the best magnetic properties, predominantly through the development of optimum grain size and favorable texture.展开更多
Based on the industrial production of non-oriented silicon steel, the rare earth （RE） treatment during the Ruhrstahl Heraeus （RH） refining process was studied. The morphology and the size distribution were observe...Based on the industrial production of non-oriented silicon steel, the rare earth （RE） treatment during the Ruhrstahl Heraeus （RH） refining process was studied. The morphology and the size distribution were observed for the steel specimens treated with different RE treatment conditions. Furthermore, the formation and change of the nonmetallic inclusion characteristics of finished steel sheets after the RE treatment were discussed. The results have shown that in the present work,the suitable RE metal additions are 0.6 -0.9 kg/t steel. After the suitable RE treatment,the formation of AIN and MnS inclusions were restrained, and the aggregation, flotation and removal of nonmetallic inclusions were efficiently promoted and the cleanliness of liquid steel was significantly increased. Meanwhile, the total oxygen concentration reached the minimum value and thle desulfurization efficiency was optimal ,and the type of main inclusions was approximately spherical or elliptical spherical RE radicle inclusions whose size was relatively large.展开更多
Based on the industrial production of non-oriented silicon steel,calcium treatment by CaSi wire feeding during the RH refining process was studied. The thermodynamics of CaS inclusion formation was analyzed, and the m...Based on the industrial production of non-oriented silicon steel,calcium treatment by CaSi wire feeding during the RH refining process was studied. The thermodynamics of CaS inclusion formation was analyzed, and the morphology and the size distribution were observed. Furthermore, the change in inclusion characteristics after calcium treatment and the effect of calcium treatment on magnetic properties were discussed. The results show that the formation of MnS and A1N inclusions were restrained, and the aggregating, floating and removing of microinclusions after calcium treatment were effectively promoted. The cleanliness of liquid steel was obviously increased. The main type of inclusions was single phase of CaO, with some complex inclusions composed of CaO, SiO2 and MgO. No CaS inclusion was observed after an appropriate calcium treatment. The size of all inclusions was distributed in the range of 2 - 20 μm, and the number was about 1.8 × 10^5/mm3. In addition, as an increasing amount of calcium was added,the core loss gradually decreased to a stable level, and the magnetic induction decreased quickly after a slow increase. The optimal calcium treatment mode depends on the chemical composition of steel.展开更多
The effects of deformation on the microstructure and magnetic properties of non oriented electrical steels were investigated. Box annealed electrical steel sheets were deformed by tension at four different strains： 3...The effects of deformation on the microstructure and magnetic properties of non oriented electrical steels were investigated. Box annealed electrical steel sheets were deformed by tension at four different strains： 3%, 8%, 12 % and 25 % The internal grain misorientation caused by tensile deformation was measured by electron backscat- tering diffraction （EBSD） with grain orientation spread （GOS） as an indicator of the lattice distortion. The experi- mental results showed that the average GOS value increases with the strain. The microstructure and crystallographic texture of deformed samples did not show a significant change in samples strained below 25 %. However, the mag- netic properties were strongly affected： coercivity was directly proportional to the square root of the GOS value and energy losses increased as the strain level was increased.展开更多
The fatigue behavior of 30 WGP1600 non-oriented electrical steel, which is generally used in the motors for electrical vehicles, was investigated. The detailed microstructure and dislocation configurations of the fati...The fatigue behavior of 30 WGP1600 non-oriented electrical steel, which is generally used in the motors for electrical vehicles, was investigated. The detailed microstructure and dislocation configurations of the fatigue specimens were examined by OM, SEM, and TEM. The test results showed that fatigue cracks were commonly initiated from the surface grain boundaries, crystals plane, and inclusions. The rapid fatigue crack propagation was characterized by transgranular cleavage fracture, while most transient fracture exhibited ductile tearing characteristics. After cyclic deformation of the non-oriented electrical steels, various dislocation structures, such as short and thick lines, veins, persistent slip bands, cells, and labyrinth, were observed.展开更多
A novel processing route involving strip casting, pre-annealing treatment, cold rolling and recrystallization annealing was applied to a Fe-2.6%Si steel to improve the magnetic properties. The impact of as-cast strip ...A novel processing route involving strip casting, pre-annealing treatment, cold rolling and recrystallization annealing was applied to a Fe-2.6%Si steel to improve the magnetic properties. The impact of as-cast strip pre-annealing on the microstructure, texture, precipitation and magnetic properties were investigated by electron probe micro-analysis, transmission electron microscopy, and X-ray diffraction analysis,etc. It was found that the precipitation of second-phase particles during strip casting was restrained by rapid solidification. The absence of pre-annealing led to the occurrence of a large amount of 20-50 nm Mn S precipitates in the final annealed sheets, which is responsible for fine grains and high core loss（4.01 W/kg） due to grain boundary pinning effect. Although the microstructure and texture of 900-1000？C pre-annealed samples were similar to those of as-cast strip, significant grain coarsening together with the strengthening of-fiber texture was observed in the 1100？C pre-annealed strips. In comparison with the case of as-cast strip, a higher amount of large-sized precipitates consisting of manganese sulfide and/or aluminum nitride occurred in matrix after pre-annealing. Correspondingly, in the final annealed sheets, the number density of precipitates with sizes smaller than 100 nm was substantially reduced, and100-200 nm and 200-500 nm sized particles became more dominant in samples subjected to 30-min and 120-min pre-annealing treatments respectively. In addition, the average grain size of final annealed sheets increased with the pre-annealing temperature and time because of the weakened pining effect of coarsen precipitates. Ultimately, the magnetic induction of samples subjected to pre-annealing was slightly increased and ranged from 1.73 T to 1.75 T owing to the enhancement of {100} recrystallization texture, and simultaneously the core loss significantly decreased until a minimum of 3.26 W/kg was reached. Nevertheless, large number of 200-500 nm particles presented during pre-annealing for 120 min could weaken the improvement in core loss which is likely associated with the pinning effect on magnetic domain wall.展开更多
基金supports from the National Natural Science Foundation of China(NSFC)(Nos.51901091 and 52374316)the Yunnan Science and Technology Program(Nos.202401AT070403 and 202305AF150014).
文摘Over the years,the high magnetic induction of industrial Mn-added electrical steel is assumed to be the enhancement of{100}texture derived from its austenite-ferrite phase transformation during hot rolling(phase transformation(PT)method).However,it is still undetermined without straightforward experimental evidence.The reason for{100}texture improvement of Mn-added electrical steel is experimentally confirmed due to the recrystallization induced by the austenite-ferrite phase transformation during hot rolling.Moreover,a more promising methodology to further improve{100}texture and formability of hot-rolled electrical steel is promoted by the control of hot rolling deformation condition(shear deformation(SD)method).The results show that the nucleation mechanisms of{100}oriented recrystallized grains are different in the samples by SD and PT methods,which are in-depth shear deformation and austenite-ferrite phase transformation,respectively.In this case,coarse{100}oriented recrystallized grains and low residual stress are obtained in the sample by SD method,which is responsible for its superior{100}texture and formability.In contrast,the sample by PT method forms fine recrystallized grains with random orientations and accumulates severe residual stress.
基金support from the National Natural Science Foundation of China (Grant Nos.52104342 and U22A20171)Hebei Natural Science Foundation (Grant No.E2021203062)the High Steel Center (HSC)at Yanshan University,Hebei Innovation Center of the Development and Application of High Quality Steel Materials,Hebei International Research Center of Advanced and Intelligent Manufacturing of High Quality Steel Materials.
文摘The effect of lanthanum on the characteristics of inclusions in the slab of non-oriented electrical steels was investigated through industrial trials and thermodynamic analysis.The number,size,and chemical composition of inclusions in the surface,one-quarter of thickness and the center of slabs with and without lanthanum addition were statistically analyzed using an automatic inclusion analysis system.In the lanthanum-free slab,inclusions were predominately MgO.Al_(2)O_(3),MgO,and AlN as well as a small number of Al_(2)O_(3)-MgO-CaO and MgS.The number densities of oxide inclusions and AlN decreased from the surface to the center of the slab,which was ascribed to the difference in cooling intensity during the continuous casting.In the steel with lanthanum addition,inclusions were modified into LaAlO_(3) and La_(2)O_(2)S and gradually transformed into dual-phase MgO-La_(2)S3 with an increasing distance from the slab surface due to the reaction between the lanthanum-containing inclusion and the steel matrix.The uneven distribution of oxide inclusions along the thickness of the slab was eliminated in the lanthanum-bearing slab because the dissolved oxygen was remarkably decreased by lanthanum.Lanthanum-bearing inclusions were more likely to agglomerate AlN by inducing the heterogeneous nucleation of AlN on their surface,while small-size MgO.Al_(2)O_(3) inclusions hardly showed a coarsening effect on the size of AlN.
基金supported by the National Natural Science Foundation of China(Nos.52074200,52274393)the Science and Technology Project of Hubei Province(2023BAB141)+1 种基金the Natural Science Foundation of Hubei Province(2022CFB091)the State Key Laboratory for Advanced Metals and Materials(2023-ZD03).
文摘High performance e-motors require a continuous enhancement of physical and mechanical properties for non-oriented electrical steel(NOES).However,the optimization of mechanical and magnetic properties simultaneously during NOES processing is extremely challenging where both properties directly influenced by alloy grain size,crystallographic texture,and dislocation density.In the current investigation,recrystallization annealing cycles were employed to modify the microstructure with the aim of balance magnetic and mechanical properties of NOES concurrently.The results showed that with increasing annealing temperatures,the degree of recrystallization and grain size increased,while the dislocation density reduced considerably at the early stage of recrystallization.Meanwhile,the values of texture parameter A*_(overall)(which is a function of overall individual grain orientations and their alignments with easy magnetization directions)were increased.It was evident that the magnetic properties were significantly improved,however the alloy strength was reduced with increasing annealing temperatures.Here,the correlation between magnetic properties as well as alloy strength on grain size,texture,and dislocation density were determined.From crystallographic texture intensity and measured properties quantitative analyses it was concluded that grain size was the predominant factor in balancing the mechanical and magnetic properties of the studied steel.Furthermore,the optimal comprehensive properties(both magnetic and mechanical)were achieved by annealing at 800℃,which yielded a magnetic induction B5000 of 1.616 T,a high-frequency iron loss P_(1.0/400)of 22.43 W/kg,and a yield strength of 527 MPa.
基金The National Natural Science Foundation of China(Nos.52130408 and 52204356)the Natural Science Foundation of Hunan Province,China(2023JJ40762)the National Key Research and Development Program of China(No.2021YFB3702401)are greatly acknowledged.
文摘Sub-rapid solidification has the potential to enhance the columnar structure and the magnetic property of electrical steels.However,research on the hot deformation behavior of sub-rapid solidified non-oriented electrical steel,particularly at varying strain rates,has yet to be fully understood.The effect of thermal compression on the microstructure and mechanical properties of 3.15 wt.%Si non-oriented electrical steel strips produced through a strip casting simulator was systematically investigated.The findings reveal that increasing the deformation temperature enhances grain recrystallization,while the peak stress decreases with higher temperature.Furthermore,a lower strain rate favors dynamic recrystallization and reduces thermal stress.It can be seen that sub-rapid solidification can effectively reduce the thermal activation energy of non-oriented electrical steel,and the thermal activation energy is calculated to be 204.411 kJ/mol.In addition,the kinetic models for the dynamic recrystallization volume fraction of the studied 3.15 wt.%Si non-oriented electrical steel were established.
基金This work was supported by the National Natural Science Foundation of China(Grant Nos.52174355,51701021,51974032,and 51604034)the China Postdoctoral Science Foundation funded project(Grant Nos.2022T150074 and 2021M693904)the Science and Technology Development Program of Jilin Province(Grant No.20230201149GX).
文摘The evolution of microstructure,texture,and magnetic properties with random texture,near-copper texture,weak near-cube texture,and strong λ fiber(<001>/ND(normal direction))before rolling of non-oriented electrical steel was studied.Three recrystallized hot bands with different textures but similar grain sizes were prepared by pre-annealing at low-temperature and high-temperature normalization annealing.It was observed that the final annealed products exhibited similar recrystallized microstructures.By contrast,the final annealed product with more 2 fiber before rolling exhibited a stronger cube texture.With the fiber before rolling becoming stronger,the proportion of(111)<110>deformed matrices became larger,which could be observed in the early recrystallization stage.The overwhelmingly dominant 2 orientation nuclei are formed in the(111)<110>deformed matrix and become the dominant texture.Eventually,the best magnetic properties are obtained in the products with strong 2 fiber before rolling,corresponding to the strong cube texture and low anisotropyparameter.
文摘The effect of lanthanum content in the range of 04）.01 1 wt.%, on the inclusion size distribution, microstructure, texture and magnetic properties of three non-oriented electrical steels was studied. After final annealing, lanthanum effectively inhibited the precipitation of MnS precipitates in steel, the formations of La2O2S and LaS inclusions not only acted as nuclei of AlN precipitates, but also combined with A1203 and formed composite inclusions with larger size. Grain size firstly increased and then decreased with lanthanum content increasing. Steel containing 0.0066 wt.% lanthanum obtained the largest grain size, the strongest { 110} 〈 110〉 texture and the weakest { 112}〈110〉 texture among all the tested steels. Magnetic flux density firstly increased and then decreased, core loss firstly dramatically decreased and then slightly decreased with lanthanum content increasing. Among the three tested steels, steel with 0.0066 wt.% lanthanum demonstrated the best comprehensive magnetic properties mainly through the development of favorable texture and appropriate final grain size.
文摘The effects of Sn addition on core loss and texture of non-oriented electrical steels were investigated. Experiments revealed that the core loss of non-oriented electrical steels could be obviously decreased and the intensity of {111 } texture and { 112} texture of final annealed specimens could be markedly reduced by Sn addition. The reasons for reducing core loss and the intensity of unfavorable texture were analyzed.
基金Mega-Projects of Science Research for the 10th Five-Year Plan (2004BA318B)
文摘Combining with the study of analogue experiments and test analysis, the kinetics of precipitation and growth of AlN and MnS in non-oriented electrical steel produced by the CSP process is calculated. The results show that the precipitate phase particles of AlN and MnS in typical non-oriented electrical steel grades produced by the CSP process have grown to some extent in the soaking stage, but the precipitation contents are less than 20% of the total contents of nitride and sulfide. The precipitate phase particles of AlN and MnS have precipitated almost after the hot rolling process. The precipitation contents are more than 80% of the total contents of nitride and sulfide, but it is very late for the precipitate phase particles to grow at the end of the hot rolling process.
基金Item Sponsored by National Natural Science Foundation of China (50874010 ,50802008) Program for New Century Excellent Talents in University of China (NCET-05-0101)
文摘The effects of heating rate （ranging from 50 to 300 ℃/s） during the final annealing process on microstructure evolution and magnetic properties of cold rolled non-oriented electrical steel were investigated. It was found that increasing heating rate increased the nucleation temperature and complete recrystallization temperature. At the same time, heating rate increasing could cause the substantially refined structures for the recrystallization grains and this grain refinement would decline when the heating rate was beyond 50 ℃/s. The recrystallization texture exhibited pronounced improvement with heating rate, such as the intensity decrease of 〈111〉//ND （normal direction） fiber and the intensity increase of { 110}%〈001〉 Goss texture component. The texture improvement and grain size refinement caused by heating rate increasing resulted in complicated variation of the magnetic properties. The magnetic induction （B50） keeps increasing while heating rate increases from 15 to 300 ℃/s which is due to the recrystallized texture optimization caused by rapid heating. The core losses （P1.5/50） decrease while heating rate increases from 15 to 100 ℃/s; however, the core losses would increase when heating rate is higher than 100 ℃/s, which is caused by the mean grain size refinement after rapid heating annealing. The results indicate that recrystallization texture and the magnetic properties of the non-oriented electrical steel can be improved definitely by rapid heating during the final annealing treatment.
基金National Key R&D Program of China(Grant No.2016YFB0300305)National Natural Science Foundation of China(Grant Nos.51671049 and 51931002)the Postdoctoral Science Foundation of China(Grant No.2018M640257).
文摘High-grade non-oriented silicon steel with higher permeability and lower core loss has become the pursed target with the rapid developnient of electrical machines.The effects of rare-earth(RE)element on recrystallization texture in RE-doped Fe-3.1 wt.%Si-1.2 wt.%Al non-oriented silicon steel were investigated by macro-and micro-texture analyses.Nonlinear variation of recrystallization texture with RE element content was observed.In the competition among main recrystallization texture components,favorable{113}<361>and X fiber(<001>//ND)are strengthened and unfavorable y fiber is evidently decreased by the addition of RE element,whereas the effect of RE element is reversed by excess RE element.The recrystallization texture development is determined by RE-affected nucleation and grain growth in terms of grain boundary migration related to segregation and inclusion.The properly inhibited grain boundary mobility can promote favorable recrystallization texture by the improved nucleation and efficient grain growth.
基金supported by the Inner Mongolia Nature Fund(2015MS0551)Inner Mongolia Science&Technology Plan(414060901)
文摘Non-oriented silicon steels containing different mass fractions of lanthanum were prepared using a high-frequency suspended furnace.Microstructures were observed by a metallographic microscope and micro-orientations were analyzed by a scanning electron microscope（SEM）.The results showed that at the annealing temperature of 870℃,recrystallization started at 90 s and completed at 120 s during annealing.Without lanthanum,no matter Cube or {111 }110 grains,recrystallized grains nucleated mainly in deformed {111}110 and {113}031 grains.With lanthanum,however,they nucleated in the deformed {110} and {112}132grains.This indicated that addition of lanthanum changed the micro-orientation relationship between new grains and the matrix.
基金This work was supported by the National Natural Science Foundation of China(Nos.5170413151464011,and 51664021)the Natural Science Foundation of Jiangxi Province,China(No.20171ACB20020)the Doctor Start-up Foundation at Jiangxi University of Science and Technology(No.jxxjbs 16005).
文摘Thin-gauge non-oriented electrical steel sheets of 0.2 mm in thickness with high magnetic induction and low core loss were produced by a two-stage cold-rolling method with and without normalization annealing.The through-process texture evolutions of the two processes were compared and studied by means of X-ray diffractometer and electron backscattered diffraction.Results showed that excellent magnetic properties were attributed to strong η-fiber recrystallization texture in the final sheet.Coarse γ-fiber-oriented grains after intermediate annealing and medium cold-rolling reduction were considered key factors to obtain a strong γ-fiber texture given that a large number of shear bands within the γ-fiber deformed matrix provided dominant nucleation sites for η-fiber-oriented grains.The normalization annealing after hot rolling was favorable for the retention of cube texture,thereby decreasing the magnetic anisotropy of thin-gauge non-oriented electrical steels.
基金support from the National Natural Science Foundation of China(Nos.51674080,51404155 and U1260204)the National Key R&D Program of China(No.2017YFB0304105)
文摘In this study, two types of as-cast microstructure produced by strip casting were cold rolled and annealed to investigate the effect of initial microstructure on the textural evolution and magnetic properties of non-oriented silicon steel. The results indicated that the cold-rolled sheets of coarse-grained strip with pronounced {100} components exhibited stronger 入 fiber(<100>//ND) and weaker γ fiber(<111>//ND)texture as composed to the fine-grained strip with strong Goss({110}(001)) texture. After annealing, the former was dominated by η fiber(<001>//RD) texture with a peak at {110}<001)orientation, while the latter consisted of strong {111}(112) and relatively weak {110}(001) texture. In addition, a number of precipitates of size ～30-150 nm restricted the grain growth during annealing, resulting in recrystallization of grain size of ～46 μm in the coarse-grained specimen and ～41μm in the fine-grained specimen.Ultimately, higher magnetic induction(～1.72 T) and lower core loss(～4.04 W/kg) were obtained in the final annealed sheets of coarse-grained strip with strong {100} texture.
基金financially supported by the National Natural Science Foundation of China(Nos.50734001 and 51004035)
文摘Aluminum nitride （AIN） precipitates and microstructure of 4 wt.% （Si＋AI） non-oriented electrical steel were investigated. The 2.0 mm thick cast strips with three different silicon/aluminum （Si/AI） ratios were produced by twin-roll casting process, then the strips were reheated, warm rolled, cold rolled and annealed. The microstructure and AIN precipitates were characterized using optical microscopy, scanning electron microscopy and transmission electron microscopy. The results showed that with the increase of Si/AI ratio, on the one hand, the casting microstructure changed from columnar grains to equiaxed grains, and the uniformity of annealed microstructure was improved; On the other hand, the number of AIN precipitates in cast strips reduced meanwhile the distribution became dispersed. By the reheat treatment, the size and distribution of the AIN precipitates can be changed. Moreover, the grain size of the annealed strips is in the range of 20-50 #m, at the same time, many AIN precipitates were located at grain boundaries. Therefore, controlling the Si/AI ratio is a simple method to obtain desired microstructure. Then AIN precipitates in non-oriented electrical steel prepared by twin-roll casting process hinder markedly the recrystallized grains growth, A compatible reheat treatment can be an approach worth exploring to control the behavior of AIN precipitates.
基金financial supports by the Xinyu Iron and Steel Company of China
文摘The effects of boron content in the range of 0-0.0082 wt%, on the inclusion type, microstructurc, texture and magnetic properties of non-oriented electrical steels have been studied. After final annealing, the addition of excess boron（w（B0〉0.004 1 wt%） led to the formation of Fe2B particles. As boron content increased, grain size increased and reached a maximum in steel with 0.004 1 wt% boron. Furthermore, steel containing 0.004 1 wt% boron had the strongest { 100} fiber texture, Goss texture and the weakest { 111 } fiber texture among the five tested steels. Flux density firstly rapidly increased and then suddenly decreased with increasing boron content and reached a maximum in steel with 0.004 1 wt% boron. Conversely, core loss first sharply decreased and then abruptly increased with the increase of boron content and reached a minimum in steel containing 0.004 1 wt% boron. Steel containing 0.004 1 wt% boron obtained the best magnetic properties, predominantly through the development of optimum grain size and favorable texture.
文摘Based on the industrial production of non-oriented silicon steel, the rare earth （RE） treatment during the Ruhrstahl Heraeus （RH） refining process was studied. The morphology and the size distribution were observed for the steel specimens treated with different RE treatment conditions. Furthermore, the formation and change of the nonmetallic inclusion characteristics of finished steel sheets after the RE treatment were discussed. The results have shown that in the present work,the suitable RE metal additions are 0.6 -0.9 kg/t steel. After the suitable RE treatment,the formation of AIN and MnS inclusions were restrained, and the aggregation, flotation and removal of nonmetallic inclusions were efficiently promoted and the cleanliness of liquid steel was significantly increased. Meanwhile, the total oxygen concentration reached the minimum value and thle desulfurization efficiency was optimal ,and the type of main inclusions was approximately spherical or elliptical spherical RE radicle inclusions whose size was relatively large.
文摘Based on the industrial production of non-oriented silicon steel,calcium treatment by CaSi wire feeding during the RH refining process was studied. The thermodynamics of CaS inclusion formation was analyzed, and the morphology and the size distribution were observed. Furthermore, the change in inclusion characteristics after calcium treatment and the effect of calcium treatment on magnetic properties were discussed. The results show that the formation of MnS and A1N inclusions were restrained, and the aggregating, floating and removing of microinclusions after calcium treatment were effectively promoted. The cleanliness of liquid steel was obviously increased. The main type of inclusions was single phase of CaO, with some complex inclusions composed of CaO, SiO2 and MgO. No CaS inclusion was observed after an appropriate calcium treatment. The size of all inclusions was distributed in the range of 2 - 20 μm, and the number was about 1.8 × 10^5/mm3. In addition, as an increasing amount of calcium was added,the core loss gradually decreased to a stable level, and the magnetic induction decreased quickly after a slow increase. The optimal calcium treatment mode depends on the chemical composition of steel.
文摘The effects of deformation on the microstructure and magnetic properties of non oriented electrical steels were investigated. Box annealed electrical steel sheets were deformed by tension at four different strains： 3%, 8%, 12 % and 25 % The internal grain misorientation caused by tensile deformation was measured by electron backscat- tering diffraction （EBSD） with grain orientation spread （GOS） as an indicator of the lattice distortion. The experi- mental results showed that the average GOS value increases with the strain. The microstructure and crystallographic texture of deformed samples did not show a significant change in samples strained below 25 %. However, the mag- netic properties were strongly affected： coercivity was directly proportional to the square root of the GOS value and energy losses increased as the strain level was increased.
基金Funded by the High Technology Research and Development Program of China(2011AA11A238)
文摘The fatigue behavior of 30 WGP1600 non-oriented electrical steel, which is generally used in the motors for electrical vehicles, was investigated. The detailed microstructure and dislocation configurations of the fatigue specimens were examined by OM, SEM, and TEM. The test results showed that fatigue cracks were commonly initiated from the surface grain boundaries, crystals plane, and inclusions. The rapid fatigue crack propagation was characterized by transgranular cleavage fracture, while most transient fracture exhibited ductile tearing characteristics. After cyclic deformation of the non-oriented electrical steels, various dislocation structures, such as short and thick lines, veins, persistent slip bands, cells, and labyrinth, were observed.
基金financially supported by the National Natural Science Foundation of China(Nos.51674080,51404155 and U1260204)the Program for New Century Excellent Talents in University(No.NCET-13-0111)+1 种基金the Program for Liaoning Excellent Talents in University(No.LR2014007)support from the University of Texas at El Paso
文摘A novel processing route involving strip casting, pre-annealing treatment, cold rolling and recrystallization annealing was applied to a Fe-2.6%Si steel to improve the magnetic properties. The impact of as-cast strip pre-annealing on the microstructure, texture, precipitation and magnetic properties were investigated by electron probe micro-analysis, transmission electron microscopy, and X-ray diffraction analysis,etc. It was found that the precipitation of second-phase particles during strip casting was restrained by rapid solidification. The absence of pre-annealing led to the occurrence of a large amount of 20-50 nm Mn S precipitates in the final annealed sheets, which is responsible for fine grains and high core loss（4.01 W/kg） due to grain boundary pinning effect. Although the microstructure and texture of 900-1000？C pre-annealed samples were similar to those of as-cast strip, significant grain coarsening together with the strengthening of-fiber texture was observed in the 1100？C pre-annealed strips. In comparison with the case of as-cast strip, a higher amount of large-sized precipitates consisting of manganese sulfide and/or aluminum nitride occurred in matrix after pre-annealing. Correspondingly, in the final annealed sheets, the number density of precipitates with sizes smaller than 100 nm was substantially reduced, and100-200 nm and 200-500 nm sized particles became more dominant in samples subjected to 30-min and 120-min pre-annealing treatments respectively. In addition, the average grain size of final annealed sheets increased with the pre-annealing temperature and time because of the weakened pining effect of coarsen precipitates. Ultimately, the magnetic induction of samples subjected to pre-annealing was slightly increased and ranged from 1.73 T to 1.75 T owing to the enhancement of {100} recrystallization texture, and simultaneously the core loss significantly decreased until a minimum of 3.26 W/kg was reached. Nevertheless, large number of 200-500 nm particles presented during pre-annealing for 120 min could weaken the improvement in core loss which is likely associated with the pinning effect on magnetic domain wall.
