Grain-oriented silicon steels were prepared at different heating rates during high temperature annealing,in which the evolution of magnetic properties,grain orientations and precipitates were studied.To illustrate the...Grain-oriented silicon steels were prepared at different heating rates during high temperature annealing,in which the evolution of magnetic properties,grain orientations and precipitates were studied.To illustrate the Zener factor,the diameter and number density of precipitates of interrupted testing samples were statistically calculated.The effect of precipitate ripening on the Goss texture and magnetic property was investigated.Data indicated that the trend of Zener factor was similar under different heating rates,first increasing and then decreasing,and that the precipitate maturing was greatly inhibited as the heating rate increased.Secondary recrystallization was developed at the temperature of 1010℃when a heating rate of 5℃/h was used,resulting in Goss,Brass and{110}<227>oriented grains growing abnormally and a magnetic induction intensity of 1.90T.Furthermore,increasing the heating rate to 20℃/h would inhibit the development of undesirable oriented grains and obtain a sharp Goss texture.However,when the heating rate was extremely fast,such as 40℃/h,poor secondary recrystallization was developed with many island grains,corresponding to a decrease in magnetic induction intensity to 1.87 T.At a suitable heating rate of 20℃/h,the sharpest Goss texture and the highest magnetic induction of 1.94 T with an onset secondary recrystallization temperature of 1020℃were found among the experimental variables in this study.The heating rate affected the initial temperature of secondary recrystallization by controlling the maturation of precipitates,leading to the deviation and dispersion of Goss texture,thereby reducing the magnetic properties.展开更多
The recrystallization texture in grain oriented silicon steel sheets, which were annealed at different primary annealingtemperatures with and without an electric field, was investigated. An automated electron backscat...The recrystallization texture in grain oriented silicon steel sheets, which were annealed at different primary annealingtemperatures with and without an electric field, was investigated. An automated electron backscattered diffraction(EBSD) technique was used to analyze the recrystallization texture. It was found that recovery and application ofelectric field in primary annealing lead to an increase of {001} component and a decrease of {111} component afterannealing at 900℃. The development of recrystallization texture can be explained in terms of the effects of electricfield and primary annealing temperature on recovery.展开更多
The second phase particles were observed during the whole manufacturing process of conventional grain oriented electrical steels, exhibiting that the areal density of particles in the center was obviously higher than ...The second phase particles were observed during the whole manufacturing process of conventional grain oriented electrical steels, exhibiting that the areal density of particles in the center was obviously higher than that on the surface at each manufacturing stage. After hot rolling, the approximately equiaxed grains formed upon recrystallization were present on the sheet surface while the deformation structures were retained in the central part. Thus, the dislocation density on the surface was evidently lower than that in the center and this trend became more noticeable after the first cold rolling. Since new precipitates were mainly nucleated at dislocations during both hot rolling and annealing following cold deformation, the difference in dislocation density resulted in the inhomogeneous distribution of particles through the thickness of sheet. According to this, Goss grains, which were usually found near the surface, tended to grow up more easily during the secondary recrystallization treatment.展开更多
High energy synchrotron diffraction offers great potential to study the recrystallization kinetics of metallic materials. To study the formation of Goss texture （{ [10}（001）） of grain oriented （GO） silicon steel...High energy synchrotron diffraction offers great potential to study the recrystallization kinetics of metallic materials. To study the formation of Goss texture （{ [10}（001）） of grain oriented （GO） silicon steel during secondary recrystallization process, an in situ experiment using hi gh energy X-ray diffraction was designed. The results showed that the secondary recrystallization began when the heating temperature was 1,494 K, and the grains grew rapidly above this temperature. With an increase in annealing temperature, the large grains with 7 orientation [〈111〉//normal direction] formed and gradually occupied the dominant position. As the annealing temperature increased even further, the grains with Goss orientation to a very large size by devouring the 7 orientation grains that formed in the early annealing stage. A single crystal with a Goss orientation was observed in the GO silicon steel when the annealing temperature was 1,540 K.展开更多
CW-CO2 laser nitriding technique was applied to improve the properties （such as aging property and the core loss） of grain oriented silicon steel. The samples were nitrided with regular space. Laser power density an...CW-CO2 laser nitriding technique was applied to improve the properties （such as aging property and the core loss） of grain oriented silicon steel. The samples were nitrided with regular space. Laser power density and scanning speed were chosen as 7.8×10^5W·cm^-2 and 100mm·min^-1. By some laser irradiation, Fe4N and Fe3N were formed in the nitrided zone. The nitrided samples were annealed at the temperatures ranged from 100 to 90℃. The core loss of some interested samples was tested. The results show that the core loss of the nitrided samples with different thickness of 0.23 and 0.30mm decreased by 14.9% and 9.4% respectively, and the aging property were improved up to 800℃. The mechanism of laser nitriding to improve the properties of grain oriented silicon steel is discussed.展开更多
The magnetic properties and textures of grain oriented silicon steel with different thickness rolled by cross shear rolling （CSR） of different mismatched speed ratio （MSR） and annealed in magnetic field under hyd...The magnetic properties and textures of grain oriented silicon steel with different thickness rolled by cross shear rolling （CSR） of different mismatched speed ratio （MSR） and annealed in magnetic field under hydrogen were presented.Effects of the factors such as thickness and mismatched speed ratio on the magnetic properties and recrystallization texture were analyzed and the recrystallization principles in magnetic field annealing were discussed. The study would provide a new route for mass production of high quality ultra-thin grain oriented silicon steel strip.展开更多
The Hi-B silicon steels were cold rolled by cross shear rolling (CSR) with different mismatch speed ratio(MSR)s and conventional rolling(CR) respectively, followed by primary recrystallization annealing. The effects o...The Hi-B silicon steels were cold rolled by cross shear rolling (CSR) with different mismatch speed ratio(MSR)s and conventional rolling(CR) respectively, followed by primary recrystallization annealing. The effects of MSR and annealing temperature on magnetic properties of ultra-thin grain oriented silicon steel were analyzed. Experimental results show that, with the increase of MSR, the magnetic properties can be remarkably improved. The higher the annealing temperature is, the higher the magnetic induction and the lower the iron loss in ultra-thin silicon steel is.展开更多
Commercial grain oriented silicon steel was cold rolled to thickness from 0.06 to 0.10 mm by cross shear rolling, then annealed in vacuum or a hydrogen atmosphere furnace. Deformation textures of the sheets were resea...Commercial grain oriented silicon steel was cold rolled to thickness from 0.06 to 0.10 mm by cross shear rolling, then annealed in vacuum or a hydrogen atmosphere furnace. Deformation textures of the sheets were researched by ODF method and reverse pole figure quantitative analyses. The results indicate that: in the condition of the cross shear rolling, the deformation texture of rolled sheet is generally similar to that of conventional rolled sheet, however, the texture distribution through the thickness is asymmetrical. With mismatch speed ratio increasing, the amount of Goss texture increases. With reduction ratio increasing, the intensity of γ-fiber becomes strong.展开更多
The texture inhomogeneity in cross shear rolled grain oriented Si steel was investigated by means of the through thickness texture analysis. For the chosen rolling reductions (55%, 66.5%) and mismatch speed ratios (1....The texture inhomogeneity in cross shear rolled grain oriented Si steel was investigated by means of the through thickness texture analysis. For the chosen rolling reductions (55%, 66.5%) and mismatch speed ratios (1.0, 1.1, 1.3), the deformation textures in various thickness layers consist of three major components, i.e. strong γ-fiber, medium α-fiber and weak η-fiber, and they show an asymmetrical distribution throughout the thickness. The effect of reduction on the texture gradient is found to be more significant at and near the center layer; however, the effect of mismatch speed ratio is less important. In most cases, a strong {111}<112> texture component appears in the subsurface layers, that may favour the formation of a sharp Goss texture during the subsequent annealing.展开更多
Decarburized samples of grain oriented silicon steel were coated with alone and blended magnesias and submitted to the high temperature annealing. The magnesias and their blendings were characterized using granulometr...Decarburized samples of grain oriented silicon steel were coated with alone and blended magnesias and submitted to the high temperature annealing. The magnesias and their blendings were characterized using granulometry measurements, ignition loss and reactivity tests. After high temperature annealing, forsterite film morphology, magnetic properties and Goss deviation were also analyzed. Better magnetic properties and sharper Goss orientation were found in samples which had used blended magnesias. These results are explained by the magnesias particle size distributions, forsterite film formation and rate of inhibitors release.展开更多
The grain oriented silicon strip was rolled by cross shear rolling(CSR)and then annealed to manufacture non-oriented thin silicon strip of high quality.The recrystallization of rolled grain-oriented silicon steel into...The grain oriented silicon strip was rolled by cross shear rolling(CSR)and then annealed to manufacture non-oriented thin silicon strip of high quality.The recrystallization of rolled grain-oriented silicon steel into non-oriented silicon steel was studied.For this purpose,CSR is better than conventional rolling,and the higher the mismatched speed rate is,the better the properties of the non-oriented thin silicon strip are.The optimum annealing schedule is heating at 1 000 ℃for 1hin pure hydrogen atmosphere added with H2 S of 0.001 0 %.展开更多
To reduce distribution transformer losses and carbon dioxide emissions, in recent years, the major countries in the world have issued mandatory standards for high-energy efficiency in distribution transformers. In 201...To reduce distribution transformer losses and carbon dioxide emissions, in recent years, the major countries in the world have issued mandatory standards for high-energy efficiency in distribution transformers. In 2013,China has carried out a new standard GB 20052-2013. To meet the update of the standard and energy efficiency,it is important to enhance the magnetic properties of core materials. The new products B18R065 and B20R070 which are developed by Baosteel, are successfully used for grade 1 energy efficiency distribution transformers. And Baosteel becomes one of the companies which can supply both the 0.20 mm and the 0.18 mm gauge grain oriented electrical steels （GOES） in the world. The development principle, material properties, and transformer performance of B18R065 and B20R070 were introduced,which were expected to be a useful reference for materials selection by transformer manufacturers.展开更多
For reducing the core loss of grain oriented silicon steel and improving its aging property, a new method, the LLSA by using Sb as the laser surface alloying element, was investigated, and at proper technique conditio...For reducing the core loss of grain oriented silicon steel and improving its aging property, a new method, the LLSA by using Sb as the laser surface alloying element, was investigated, and at proper technique conditions rather good result was obtained.展开更多
To investigate the evolution of grain orientation and slip modes in magnesium alloys with multiple texture components,an AZ31 gradient-structured magnesium alloy sheet was fabricated using hard plate rolling(HPR).The ...To investigate the evolution of grain orientation and slip modes in magnesium alloys with multiple texture components,an AZ31 gradient-structured magnesium alloy sheet was fabricated using hard plate rolling(HPR).The changes in texture and slip modes under different reductions were examined.The results demonstrate that the AZ31 magnesium alloy sheets display a self-epitaxial gradient structure,with the best mechanical properties observed at rolling temperature of 673 K and reduction of 50%.Significant changes in texture type and strength are observed along the normal direction(ND)of the sheet.The coarse-grain region exhibits a bimodal texture aligned with the rolling direction.These texture variations enhance the stress distribution at the fine grain-coarse grain interface,influencing the grain orientation and the activation of different slip modes,thus improving the mechanical properties of gradient-structured magnesium alloy sheets.This approach offers a new strategy for the fabrication of high-performance magnesium alloy sheets.展开更多
CaBi2Nb2O9 (CBNO) ceramics was prepared at 1050℃ using regular flake-like CBNO powders as the precursor, and synthe-sized by the molten salts synthesis method. The tropism degree and microstructure of the ceramics we...CaBi2Nb2O9 (CBNO) ceramics was prepared at 1050℃ using regular flake-like CBNO powders as the precursor, and synthe-sized by the molten salts synthesis method. The tropism degree and microstructure of the ceramics were analyzed, and the die-lectric, ferroelectric and piezoelectric properties were characterized. Compared with conventional methods, the properties of CBNO ceramics by the new preparation method were found to be better. As the sinter temperature decreases, the grain growth becomes regular with textured features. The polarization process becomes easy to be realized at room temperature. Moreover, the dielectric loss decreases and the piezoelectric constant increases significantly.展开更多
Piezoceramics with high and fatigue-resisted piezoelectric properties are strongly desired for actuator ap-plications.In this work,textured Pb(Mg_(1/3)Nb_(2/3))O_(3)-Pb(Zr,Ti)O_(3)ceramics with Lotgering factor F_(001...Piezoceramics with high and fatigue-resisted piezoelectric properties are strongly desired for actuator ap-plications.In this work,textured Pb(Mg_(1/3)Nb_(2/3))O_(3)-Pb(Zr,Ti)O_(3)ceramics with Lotgering factor F_(001)∼98%were fabricated by templated grain growth technique.Strong[001]c-grain orientation(f∼90%and r∼0.22)of the textured ceramics effectively produced about 230%enhanced piezoelectric coefficient d_(33)^(∗)(i.e.,S_(max)/E_(max))and substantially improved unipolar electrical fatigue resistance.Unipolar polarization P max and d_(33)^(∗)of the textured ceramics were nearly maintained up to 106 unipolar cycles,while 19%and 14%degradations were respectively observed from randomly oriented counterparts.Especially,normal-ized d_(33)^(∗)of the textured ceramics shows better unipolar fatigue resistance than those of piezoceramics reported previously.Much lower bipolar strain asymmetryγs(∼4%)was observed from the textured samples fatigued after 106 unipolar cycles as compared toγs∼23%for randomly oriented counterparts.While charged defect accumulation model described the serious fatigue deteriorations in randomly ori-ented ceramics,the current work revealed that substantially enhanced unipolar fatigue resistance of the textured ceramics is mainly associated with the inherent fatigue anisotropy,weakened local bias fields owing to both enhanced domain mobility and lower defect density near grain boundaries/interfaces,and increased intrinsic contribution due to more tetragonal content.These superior characteristics suggest the great potential of textured ceramics for high-performance and robust actuator applications.展开更多
Technological advancements and the emphasis on reducing the use of hazardous materials,such as Pb,have led to the widely use of Sn-based Pb-free solder in advanced packaging technology.With the miniaturization of sold...Technological advancements and the emphasis on reducing the use of hazardous materials,such as Pb,have led to the widely use of Sn-based Pb-free solder in advanced packaging technology.With the miniaturization of solder joints,Sn-based micro solder joints often contain single or limitedβ-Sn grains.The strong anisotropy ofβ-Sn,which is significantly correlated with the reliability of the micro solder joints during service,requires the development of methods for controlling the orientations of theseβ-Sn grains.In this review,we focus on the anisotropy of theβ-Sn grains in micro solder joints and the interactions betweenβ-Sn grain orientation and reliability issues concerning electromigration(EM),thermomigration(TM),EM+TM,corrosion process,tensile and shear creep behavior,thermal cycling(TC)and cryogenic temperature.Furthermore,we summarize the strategies for controlling theβ-Sn orientation in micro solder joints.The methods include changing the solder joint size and composition,adding additives,nucleating on specific substrates and interfacial intermetallic compounds,with the aid of external loads during solidification process and introducing heredity effect of theβ-Sn texture during multi-reflow.Finally,the{101}and{301}twinning models with∼60°rotations about a common〈100〉are adopted to explain the mechanism ofβ-Sn grain nucleation and morphology.The shortcomings of the existing methods and the further potential for the development in the field are discussed to promote the application of Pb-free solders in advanced packaging.展开更多
1.Introduction As one of the most widely used additive manufacturing(AM)techniques,selective laser melting(SLM)is a laser-based layer-by-layer manufacturing process,which has relatively high fabrication resolution and...1.Introduction As one of the most widely used additive manufacturing(AM)techniques,selective laser melting(SLM)is a laser-based layer-by-layer manufacturing process,which has relatively high fabrication resolution and can directly form complex metal parts.During SLM,the interaction of laser with metal powder forms a tiny melt pool.Following the rapid movement of the laser,the cooling rate of the melt pool can be as high as 105-106 K s−1[1].Such a fast cool-ing rate inhibits grain growth and element segregation in the alloy,leading to a notable enhancement in strength and toughness[2].Therefore,SLM enables unlimited possibilities in the fabrication of complex parts with high performance.To date,the most extensively researched Al alloys for SLM are Al-Si alloys,such as AlSi10Mg,Al-12Si,and AlSi7Mg[2-5].展开更多
The complex grain fragmentation mechanisms of coarse grains in titanium alloys under multi-directional forging(MDF)directly influence the optimization and control of primary hot working processes.This study conducted ...The complex grain fragmentation mechanisms of coarse grains in titanium alloys under multi-directional forging(MDF)directly influence the optimization and control of primary hot working processes.This study conducted MDF experiments onβ-phase as-cast Ti-6554 alloy and simulated non-uniform deformation during cyclic multi-directional compression through macro-and micro-deformation modeling.The results revealed that friction and surface cooling caused low strain and tensile stress concentration at billet edges,leading to mixed grain structures.In contrast,high strain and triaxial compressive stress at billet centers facilitated uniform grain refinement.After 14 compressions and 4 intermediate reheating processes,coarse grains of the billet were refined from 2-5 mm to 0.25-0.50 mm,achieving uniform grain sizes across different regions.For the first time,the orientation evolution of grains with different morphologies during multi-directional compressions was visualized microscopically.Columnar grains were found to be more easily subdivided than equiaxed grains due to local strain accumulation.Under cumulative compressions,grain orientations gradually rotated from uniform to random,driving continuous dynamic recrystallization(CDRX).Slip system interactions and concentrated misorientation led to the formation and extension of transition and shear bands,inducing grain fragmentation dominated by transgranular subdivided CDRX.Smooth grain boundaries transformed into serrated ones after multiple passes,providing additional nucleation sites for discontinuous dynamic recrystallization(DDRX)and facilitating boundary expand CDRX.The interaction of diverse DRX mechanisms was the fundamental cause of grain refinement.This study clarified the principles of refining and homogenizing millimeter-grade coarse grains under increasing forging strain,offering valuable insights for the development of primary hot processing techniques for as-castβtitanium alloys.展开更多
The corrosion behavior at open circuit potential(OCP)and discharge properties under applied anodic currents of twoα-Mg based Mg-Li alloys,i.e.,LAZ131 and LAZ531,with different microstructural features for primary Mg-...The corrosion behavior at open circuit potential(OCP)and discharge properties under applied anodic currents of twoα-Mg based Mg-Li alloys,i.e.,LAZ131 and LAZ531,with different microstructural features for primary Mg-air batteries are investigated.The results show that the grain boundaries contribute equally to the corrosion and discharge processes,which are attacked preferentially than the grain interiors and accelerate the dissolution processes ofα-Mg based Mg-Li alloys.The(10-10)/(11-20)orientated grains are attacked preferentially than the(0002)orientated grains on the corrosion and discharge process.The increased corrosion rate and improved discharge properties are attributed to the refinement of grain size,decreased content of(0002)orientated grains and increased content of(10-10)/(11-20)orientated grains.Of those,the LAZ531 alloy possesses high and steady discharge voltage at small discharge current density for long time,with the values of 1.4801 V at 2.5 mA cm^(-2)and 1.3742 V at 10 mA cm^(-2).展开更多
文摘Grain-oriented silicon steels were prepared at different heating rates during high temperature annealing,in which the evolution of magnetic properties,grain orientations and precipitates were studied.To illustrate the Zener factor,the diameter and number density of precipitates of interrupted testing samples were statistically calculated.The effect of precipitate ripening on the Goss texture and magnetic property was investigated.Data indicated that the trend of Zener factor was similar under different heating rates,first increasing and then decreasing,and that the precipitate maturing was greatly inhibited as the heating rate increased.Secondary recrystallization was developed at the temperature of 1010℃when a heating rate of 5℃/h was used,resulting in Goss,Brass and{110}<227>oriented grains growing abnormally and a magnetic induction intensity of 1.90T.Furthermore,increasing the heating rate to 20℃/h would inhibit the development of undesirable oriented grains and obtain a sharp Goss texture.However,when the heating rate was extremely fast,such as 40℃/h,poor secondary recrystallization was developed with many island grains,corresponding to a decrease in magnetic induction intensity to 1.87 T.At a suitable heating rate of 20℃/h,the sharpest Goss texture and the highest magnetic induction of 1.94 T with an onset secondary recrystallization temperature of 1020℃were found among the experimental variables in this study.The heating rate affected the initial temperature of secondary recrystallization by controlling the maturation of precipitates,leading to the deviation and dispersion of Goss texture,thereby reducing the magnetic properties.
基金The authors are grateful for the financial support from the National Natural Science Foundation of ChinaShanghai Baosteel Group Cor poration(No.50130010)+1 种基金the Natural Science Foundation of Liaoning Province(No.2001102026)the Teaching and R esearch Encouragement P rogram for Excellent Young Teachers in Universities of Ministry of China.
文摘The recrystallization texture in grain oriented silicon steel sheets, which were annealed at different primary annealingtemperatures with and without an electric field, was investigated. An automated electron backscattered diffraction(EBSD) technique was used to analyze the recrystallization texture. It was found that recovery and application ofelectric field in primary annealing lead to an increase of {001} component and a decrease of {111} component afterannealing at 900℃. The development of recrystallization texture can be explained in terms of the effects of electricfield and primary annealing temperature on recovery.
基金supported by the National Natural Science Foundation of China (No. 50871015)
文摘The second phase particles were observed during the whole manufacturing process of conventional grain oriented electrical steels, exhibiting that the areal density of particles in the center was obviously higher than that on the surface at each manufacturing stage. After hot rolling, the approximately equiaxed grains formed upon recrystallization were present on the sheet surface while the deformation structures were retained in the central part. Thus, the dislocation density on the surface was evidently lower than that in the center and this trend became more noticeable after the first cold rolling. Since new precipitates were mainly nucleated at dislocations during both hot rolling and annealing following cold deformation, the difference in dislocation density resulted in the inhomogeneous distribution of particles through the thickness of sheet. According to this, Goss grains, which were usually found near the surface, tended to grow up more easily during the secondary recrystallization treatment.
基金supported by the Key Projects of the National Science & Technology Pillar Program (No. 2011BAE13B03)the Fundamental Research Funds for the Central Universities (No. N110502001)
文摘High energy synchrotron diffraction offers great potential to study the recrystallization kinetics of metallic materials. To study the formation of Goss texture （{ [10}（001）） of grain oriented （GO） silicon steel during secondary recrystallization process, an in situ experiment using hi gh energy X-ray diffraction was designed. The results showed that the secondary recrystallization began when the heating temperature was 1,494 K, and the grains grew rapidly above this temperature. With an increase in annealing temperature, the large grains with 7 orientation [〈111〉//normal direction] formed and gradually occupied the dominant position. As the annealing temperature increased even further, the grains with Goss orientation to a very large size by devouring the 7 orientation grains that formed in the early annealing stage. A single crystal with a Goss orientation was observed in the GO silicon steel when the annealing temperature was 1,540 K.
基金supported by the National Natural Science Foundation of China(No.50174020).
文摘CW-CO2 laser nitriding technique was applied to improve the properties （such as aging property and the core loss） of grain oriented silicon steel. The samples were nitrided with regular space. Laser power density and scanning speed were chosen as 7.8×10^5W·cm^-2 and 100mm·min^-1. By some laser irradiation, Fe4N and Fe3N were formed in the nitrided zone. The nitrided samples were annealed at the temperatures ranged from 100 to 90℃. The core loss of some interested samples was tested. The results show that the core loss of the nitrided samples with different thickness of 0.23 and 0.30mm decreased by 14.9% and 9.4% respectively, and the aging property were improved up to 800℃. The mechanism of laser nitriding to improve the properties of grain oriented silicon steel is discussed.
文摘The magnetic properties and textures of grain oriented silicon steel with different thickness rolled by cross shear rolling （CSR） of different mismatched speed ratio （MSR） and annealed in magnetic field under hydrogen were presented.Effects of the factors such as thickness and mismatched speed ratio on the magnetic properties and recrystallization texture were analyzed and the recrystallization principles in magnetic field annealing were discussed. The study would provide a new route for mass production of high quality ultra-thin grain oriented silicon steel strip.
文摘The Hi-B silicon steels were cold rolled by cross shear rolling (CSR) with different mismatch speed ratio(MSR)s and conventional rolling(CR) respectively, followed by primary recrystallization annealing. The effects of MSR and annealing temperature on magnetic properties of ultra-thin grain oriented silicon steel were analyzed. Experimental results show that, with the increase of MSR, the magnetic properties can be remarkably improved. The higher the annealing temperature is, the higher the magnetic induction and the lower the iron loss in ultra-thin silicon steel is.
基金National Natural Science Foundation of China!(No. 59671037).
文摘Commercial grain oriented silicon steel was cold rolled to thickness from 0.06 to 0.10 mm by cross shear rolling, then annealed in vacuum or a hydrogen atmosphere furnace. Deformation textures of the sheets were researched by ODF method and reverse pole figure quantitative analyses. The results indicate that: in the condition of the cross shear rolling, the deformation texture of rolled sheet is generally similar to that of conventional rolled sheet, however, the texture distribution through the thickness is asymmetrical. With mismatch speed ratio increasing, the amount of Goss texture increases. With reduction ratio increasing, the intensity of γ-fiber becomes strong.
基金This work was supported by the National Natural Science Foundation of China (No. 59671037 and 50071061).
文摘The texture inhomogeneity in cross shear rolled grain oriented Si steel was investigated by means of the through thickness texture analysis. For the chosen rolling reductions (55%, 66.5%) and mismatch speed ratios (1.0, 1.1, 1.3), the deformation textures in various thickness layers consist of three major components, i.e. strong γ-fiber, medium α-fiber and weak η-fiber, and they show an asymmetrical distribution throughout the thickness. The effect of reduction on the texture gradient is found to be more significant at and near the center layer; however, the effect of mismatch speed ratio is less important. In most cases, a strong {111}<112> texture component appears in the subsurface layers, that may favour the formation of a sharp Goss texture during the subsequent annealing.
文摘Decarburized samples of grain oriented silicon steel were coated with alone and blended magnesias and submitted to the high temperature annealing. The magnesias and their blendings were characterized using granulometry measurements, ignition loss and reactivity tests. After high temperature annealing, forsterite film morphology, magnetic properties and Goss deviation were also analyzed. Better magnetic properties and sharper Goss orientation were found in samples which had used blended magnesias. These results are explained by the magnesias particle size distributions, forsterite film formation and rate of inhibitors release.
文摘The grain oriented silicon strip was rolled by cross shear rolling(CSR)and then annealed to manufacture non-oriented thin silicon strip of high quality.The recrystallization of rolled grain-oriented silicon steel into non-oriented silicon steel was studied.For this purpose,CSR is better than conventional rolling,and the higher the mismatched speed rate is,the better the properties of the non-oriented thin silicon strip are.The optimum annealing schedule is heating at 1 000 ℃for 1hin pure hydrogen atmosphere added with H2 S of 0.001 0 %.
文摘To reduce distribution transformer losses and carbon dioxide emissions, in recent years, the major countries in the world have issued mandatory standards for high-energy efficiency in distribution transformers. In 2013,China has carried out a new standard GB 20052-2013. To meet the update of the standard and energy efficiency,it is important to enhance the magnetic properties of core materials. The new products B18R065 and B20R070 which are developed by Baosteel, are successfully used for grade 1 energy efficiency distribution transformers. And Baosteel becomes one of the companies which can supply both the 0.20 mm and the 0.18 mm gauge grain oriented electrical steels （GOES） in the world. The development principle, material properties, and transformer performance of B18R065 and B20R070 were introduced,which were expected to be a useful reference for materials selection by transformer manufacturers.
基金National Natural Science FOundation of China! (No. 59974010).
文摘For reducing the core loss of grain oriented silicon steel and improving its aging property, a new method, the LLSA by using Sb as the laser surface alloying element, was investigated, and at proper technique conditions rather good result was obtained.
基金supported by the Natural Science Foundation of Heilongjiang Province,China(No.JQ2022E004)。
文摘To investigate the evolution of grain orientation and slip modes in magnesium alloys with multiple texture components,an AZ31 gradient-structured magnesium alloy sheet was fabricated using hard plate rolling(HPR).The changes in texture and slip modes under different reductions were examined.The results demonstrate that the AZ31 magnesium alloy sheets display a self-epitaxial gradient structure,with the best mechanical properties observed at rolling temperature of 673 K and reduction of 50%.Significant changes in texture type and strength are observed along the normal direction(ND)of the sheet.The coarse-grain region exhibits a bimodal texture aligned with the rolling direction.These texture variations enhance the stress distribution at the fine grain-coarse grain interface,influencing the grain orientation and the activation of different slip modes,thus improving the mechanical properties of gradient-structured magnesium alloy sheets.This approach offers a new strategy for the fabrication of high-performance magnesium alloy sheets.
基金supported by the National Natural Science Foundation of China (50632030 & 10804130)
文摘CaBi2Nb2O9 (CBNO) ceramics was prepared at 1050℃ using regular flake-like CBNO powders as the precursor, and synthe-sized by the molten salts synthesis method. The tropism degree and microstructure of the ceramics were analyzed, and the die-lectric, ferroelectric and piezoelectric properties were characterized. Compared with conventional methods, the properties of CBNO ceramics by the new preparation method were found to be better. As the sinter temperature decreases, the grain growth becomes regular with textured features. The polarization process becomes easy to be realized at room temperature. Moreover, the dielectric loss decreases and the piezoelectric constant increases significantly.
基金This work was financially supported by the National Natural Science Foundation of China(Nos.52072092 and 51922083)the Natural Science Foundation of Heilongjiang Province(No.YQ2019E026)the Fundamental Research Funds for the Central Universities(No.HIT.OCEF.2021018).
文摘Piezoceramics with high and fatigue-resisted piezoelectric properties are strongly desired for actuator ap-plications.In this work,textured Pb(Mg_(1/3)Nb_(2/3))O_(3)-Pb(Zr,Ti)O_(3)ceramics with Lotgering factor F_(001)∼98%were fabricated by templated grain growth technique.Strong[001]c-grain orientation(f∼90%and r∼0.22)of the textured ceramics effectively produced about 230%enhanced piezoelectric coefficient d_(33)^(∗)(i.e.,S_(max)/E_(max))and substantially improved unipolar electrical fatigue resistance.Unipolar polarization P max and d_(33)^(∗)of the textured ceramics were nearly maintained up to 106 unipolar cycles,while 19%and 14%degradations were respectively observed from randomly oriented counterparts.Especially,normal-ized d_(33)^(∗)of the textured ceramics shows better unipolar fatigue resistance than those of piezoceramics reported previously.Much lower bipolar strain asymmetryγs(∼4%)was observed from the textured samples fatigued after 106 unipolar cycles as compared toγs∼23%for randomly oriented counterparts.While charged defect accumulation model described the serious fatigue deteriorations in randomly ori-ented ceramics,the current work revealed that substantially enhanced unipolar fatigue resistance of the textured ceramics is mainly associated with the inherent fatigue anisotropy,weakened local bias fields owing to both enhanced domain mobility and lower defect density near grain boundaries/interfaces,and increased intrinsic contribution due to more tetragonal content.These superior characteristics suggest the great potential of textured ceramics for high-performance and robust actuator applications.
基金financially supported by the National Natural Science Foundation of China(No.52075072)the Provincial Applied Basic Research Program of Liaoning Provincial Department of Science and Technology(No.2023JH2/101300181)the Key R&D Program of Shandong Province,China(No.2022CXGC020408)。
文摘Technological advancements and the emphasis on reducing the use of hazardous materials,such as Pb,have led to the widely use of Sn-based Pb-free solder in advanced packaging technology.With the miniaturization of solder joints,Sn-based micro solder joints often contain single or limitedβ-Sn grains.The strong anisotropy ofβ-Sn,which is significantly correlated with the reliability of the micro solder joints during service,requires the development of methods for controlling the orientations of theseβ-Sn grains.In this review,we focus on the anisotropy of theβ-Sn grains in micro solder joints and the interactions betweenβ-Sn grain orientation and reliability issues concerning electromigration(EM),thermomigration(TM),EM+TM,corrosion process,tensile and shear creep behavior,thermal cycling(TC)and cryogenic temperature.Furthermore,we summarize the strategies for controlling theβ-Sn orientation in micro solder joints.The methods include changing the solder joint size and composition,adding additives,nucleating on specific substrates and interfacial intermetallic compounds,with the aid of external loads during solidification process and introducing heredity effect of theβ-Sn texture during multi-reflow.Finally,the{101}and{301}twinning models with∼60°rotations about a common〈100〉are adopted to explain the mechanism ofβ-Sn grain nucleation and morphology.The shortcomings of the existing methods and the further potential for the development in the field are discussed to promote the application of Pb-free solders in advanced packaging.
基金supported by the National Natu-ral Science Foundation of China(Nos.52071262,52301197,and 52234009)the National Key Research and Development Program(No.2022YFB3404203)+3 种基金the Natural Science Basic Research Pro-gram of Shaanxi Province,China(No.2023-JC-QN-0421)the Re-search Fund of the State Key Laboratory of Solidification Processing(NPU),China(Nos.2024-ZD-06 and 2024-TS-06)the Fundamental Research Funds for the Central Universities(No.D5000240144)the Young Talent Fund of Xi’an Association for Science and Tech-nology(No.959202413014).
文摘1.Introduction As one of the most widely used additive manufacturing(AM)techniques,selective laser melting(SLM)is a laser-based layer-by-layer manufacturing process,which has relatively high fabrication resolution and can directly form complex metal parts.During SLM,the interaction of laser with metal powder forms a tiny melt pool.Following the rapid movement of the laser,the cooling rate of the melt pool can be as high as 105-106 K s−1[1].Such a fast cool-ing rate inhibits grain growth and element segregation in the alloy,leading to a notable enhancement in strength and toughness[2].Therefore,SLM enables unlimited possibilities in the fabrication of complex parts with high performance.To date,the most extensively researched Al alloys for SLM are Al-Si alloys,such as AlSi10Mg,Al-12Si,and AlSi7Mg[2-5].
基金supported by the National Key Research and Development Program of China(No.2022YFB3706901)the National Natural Science Foundation of China(No.52274382)。
文摘The complex grain fragmentation mechanisms of coarse grains in titanium alloys under multi-directional forging(MDF)directly influence the optimization and control of primary hot working processes.This study conducted MDF experiments onβ-phase as-cast Ti-6554 alloy and simulated non-uniform deformation during cyclic multi-directional compression through macro-and micro-deformation modeling.The results revealed that friction and surface cooling caused low strain and tensile stress concentration at billet edges,leading to mixed grain structures.In contrast,high strain and triaxial compressive stress at billet centers facilitated uniform grain refinement.After 14 compressions and 4 intermediate reheating processes,coarse grains of the billet were refined from 2-5 mm to 0.25-0.50 mm,achieving uniform grain sizes across different regions.For the first time,the orientation evolution of grains with different morphologies during multi-directional compressions was visualized microscopically.Columnar grains were found to be more easily subdivided than equiaxed grains due to local strain accumulation.Under cumulative compressions,grain orientations gradually rotated from uniform to random,driving continuous dynamic recrystallization(CDRX).Slip system interactions and concentrated misorientation led to the formation and extension of transition and shear bands,inducing grain fragmentation dominated by transgranular subdivided CDRX.Smooth grain boundaries transformed into serrated ones after multiple passes,providing additional nucleation sites for discontinuous dynamic recrystallization(DDRX)and facilitating boundary expand CDRX.The interaction of diverse DRX mechanisms was the fundamental cause of grain refinement.This study clarified the principles of refining and homogenizing millimeter-grade coarse grains under increasing forging strain,offering valuable insights for the development of primary hot processing techniques for as-castβtitanium alloys.
基金financially supported by the National Key Research and Development Program of China(Nos.2016YFB0101700 and 2016YFB0301104)the National Natural Science Foundation of China(Nos.51531002,U1764253,and 51971040)+2 种基金the Chongqing Science and Technology Commission(Nos.cstc2017zdcy-zdzx X0006 and cstc2019jscx-mbdxX0031)the Chongqing Scientific&Technological Talents Program(No.KJXX2017002)the Scientific Research Foundation of Chongqing University of Technology。
文摘The corrosion behavior at open circuit potential(OCP)and discharge properties under applied anodic currents of twoα-Mg based Mg-Li alloys,i.e.,LAZ131 and LAZ531,with different microstructural features for primary Mg-air batteries are investigated.The results show that the grain boundaries contribute equally to the corrosion and discharge processes,which are attacked preferentially than the grain interiors and accelerate the dissolution processes ofα-Mg based Mg-Li alloys.The(10-10)/(11-20)orientated grains are attacked preferentially than the(0002)orientated grains on the corrosion and discharge process.The increased corrosion rate and improved discharge properties are attributed to the refinement of grain size,decreased content of(0002)orientated grains and increased content of(10-10)/(11-20)orientated grains.Of those,the LAZ531 alloy possesses high and steady discharge voltage at small discharge current density for long time,with the values of 1.4801 V at 2.5 mA cm^(-2)and 1.3742 V at 10 mA cm^(-2).
