Cold-rolled advanced high-strength steel sheets have become the material of choice for the automotive industry because of their unique attributes of high strength and balanced mechanical properties.High-hydrogen gas j...Cold-rolled advanced high-strength steel sheets have become the material of choice for the automotive industry because of their unique attributes of high strength and balanced mechanical properties.High-hydrogen gas jet cooling and water quenching are the most commonly used ultrafast cooling technologies for producing martensite-containing high-strength steel sheets.The water quenching technology ensures the fastest industrial cooling rate of 1 000 K/s;therefore,it has the highest potential with respect to saving alloys.In this study,the water quenching of a C-Mn-containing steel sheet is simulated during continuous annealing to investigate the effect of water quenching and tempering parameters on its mechanical properties.The results reveal that at low quenching temperatures,the strength of the steel sheet decreases as the soaking temperature increases.However,at high quenching temperatures,a high soaking temperature corresponds to increased strength after quenching,regardless of whether the material was austenitized in the single austenite zone or the inter-critical zone.Therefore,a high quenching temperature always results in a high strength and a high yield ratio after quenching.Low-temperature overaging(tempering) considerably influences the yield strength and yield ratio,and the extent of this influence is correlated with the soaking temperature.展开更多
Cold-rolled martensitic steel sheets produced on continuous annealing lines with water quenching facility,have advantages of high strength and low alloying element contents.These are in good accordance with the trend ...Cold-rolled martensitic steel sheets produced on continuous annealing lines with water quenching facility,have advantages of high strength and low alloying element contents.These are in good accordance with the trend of light-weighting and fuel saving for automotive steel.In this article,a cold-rolled martensitic steel is studied to investigate the effect of annealing parameters on its mechanical properties.It is found that the quenching temperature and the slow cooling speed as well as the overageing temperature have significant influence on the strength of the experimental steel.The temperature zone at which the austenite decomposition is slow or has not started may be chosen as the quenching temperature to ensure the steel's strength stability.The slow cooling speed also influences the steel's strength greatly.A high cooling rate will lead to significantly higher strength.Tempering would decrease the steel's tensile strength but would increase its yield strength.展开更多
This study presents the fatigue response of 304 stainless steel foil, cold-rolled to a thickness of 3.2 μm with 87 percent cold work at orientations of 0, 45, and 90 degrees to the direction of rolling. Fatigue speci...This study presents the fatigue response of 304 stainless steel foil, cold-rolled to a thickness of 3.2 μm with 87 percent cold work at orientations of 0, 45, and 90 degrees to the direction of rolling. Fatigue specimens were fabricated by laminating a supportive layer of 20-μm polyimide film to one side of the foil and patterning 242 crack initiation features by photolithographic process. Progression of fatigue damage was determined through electrical resistance measurement. The fatigue response was demonstrated to be largely affected by anisotropy existing between the rolling direction and the off-axis orientations. Fatigue cracks that traveled in a direction parallel to the elongated grains (cyclic loads applied at 90-degree orientation to foil rolling direction) had the most fatigue response (undesirable characteristic). The construction of the specimens with thin foil supported by a film backing contributed to high fatigue threshold.展开更多
Surface defects of the cold-rolled sheets of Ti-IF steel were studied and analyzed. After analyzing surface defects of cold-rolled sheets, such as shelling defects, holes and sliver defects by SEM/EDS, a variety of in...Surface defects of the cold-rolled sheets of Ti-IF steel were studied and analyzed. After analyzing surface defects of cold-rolled sheets, such as shelling defects, holes and sliver defects by SEM/EDS, a variety of inclusions were found. In addition, the distribution of macro-inclusions in slabs was analyzed by MIDAS method. The results show the macroscopic inclusion bands of head slabs and normal slabs are in 1/8 slab thickness regions of both inner arc side and outer arc side. The formation process of the defects in the cold-rolled sheets was simulated with an experimental cold-rolling machine for comparison. The results show that there were three kinds of inclusions underneath the surface defects: Al2O3, SiO2 and particles from slag entrainment, which were the main reason for defect formation during cold rolling.展开更多
The objective of the present study is to develop heterogeneous microstructure in cold-rolled medium Mn steels(MMSs)annealing strategy.The cold-rolled Fe-4.7Mn-0.15C(wt%)steel is annealed twice at different temperature...The objective of the present study is to develop heterogeneous microstructure in cold-rolled medium Mn steels(MMSs)annealing strategy.The cold-rolled Fe-4.7Mn-0.15C(wt%)steel is annealed twice at different temperatures to produce an ultra-fine heterogeneous microstructure with lath-shaped and granular-shaped retained austenite.Excellent mechanical behavior of significant strength enhancement with negligible ductility loss can be achieved.The high strength-ductility properties are attributed to the active transformation induced plasticity effect over a broad strain range owing to dispersive mechanical stabilities of the heterogeneous austenite.Furthermore,the typical yield point elongation phenomenon which is commonly observed in cold-rolled MMSs can be effectively reduced by this microstructural strategy.展开更多
The thermal treatment process of cold-rolled Cu-Al composite strip under magnetic field conditions is systematically investigated by means of metallographic microscope and universal testing machine to observe the inte...The thermal treatment process of cold-rolled Cu-Al composite strip under magnetic field conditions is systematically investigated by means of metallographic microscope and universal testing machine to observe the interface microstructure and test the mechanical properties.The heat treatment parameters'effects to the interface structure and mechanical properties of Al-Cu cold-rolled strip are discussed.The conclusions is showed as follows:(1)when the magnetic field intensity is greater than 0.1 T,the interface layer grow widely and stimulate the interfacial compounds'generation,the shear strength is reduced.(2)When the Cu-Al specimen's annealing temperature is at the condition of300℃,the interfacial layer narrows when the magnetic field strength stay 0.1T than that without magnetic field,the magnetic filed restrains the interfacial compounds'generation,the shear strength reaches as high as 124Mpa;(3)The interfacial compounds are meanly brittleness intermetallic compounds such as CuAl,CuAl_2,Cu_9Al_4.展开更多
Texture evolution of high-manganese twining-induced plasticity (TWIP) steels (Fe-16Mn-0.6C) during cold-rolling is studied by means of quantitative orientation distribution function (ODF)analysis.Thickness reductions ...Texture evolution of high-manganese twining-induced plasticity (TWIP) steels (Fe-16Mn-0.6C) during cold-rolling is studied by means of quantitative orientation distribution function (ODF)analysis.Thickness reductions of the specimens during cold-rolling are 10%,20%,30%,50% and 65%,respectively.Evolution of texture is of the Brass type,which is typical for low-stacking fault energy (SFE) materials.The contribution of deformation twinning to the development of texture is clearly illustrated by the monotonic increase of the twinned Cu component.In the present study,the deformation twinning was identified as significantly contributing to deformation up to the maximum reduction applied.These results are useful for the prediction and control of the texture in TWIP steels.展开更多
Many advanced technologies have been applied in developing the automatic measuring device for testing transverse thickness difference of cold-rolling steel sheet,such as the technologies of automatic control,sensor me...Many advanced technologies have been applied in developing the automatic measuring device for testing transverse thickness difference of cold-rolling steel sheet,such as the technologies of automatic control,sensor measurement,marking identification,photographic location,computer application and information transmission.This measuring device can measure the transverse thickness difference of the steel plate accurately and quickly,with a high detection level of automation.It is an effective detection equipment for transverse thickness control of steel plate.Horizontal width of steel plate measuring 0.8-1.4 m, horizontal measurement point positioning accuracy±0.02 mm,thickness range 0.2-2.0 mm, measurement accuracy within±1μm.展开更多
For the purpose of developing a 1 500 MPa grade steel sheet with excellent strength and ductility, a 0.15C-10Mn-1.5Al steel was employed to study austenite stability and microstructural evolution based on a novel doub...For the purpose of developing a 1 500 MPa grade steel sheet with excellent strength and ductility, a 0.15C-10Mn-1.5Al steel was employed to study austenite stability and microstructural evolution based on a novel double annealing processing.After a conventional intercritical annealing process, the sample was heated again to a temperature higher than A_(c3) for a very short time to generate austenite grains with different manganese content;thus, the microstructure of martensite plus austenite can be obtained at room temperature.The experimental results show that with increasing annealing temperature, the tensile strength and yield strength increase.When the annealing temperature was higher than 820 ℃,the microstructure consisted of martensite plus austenite, and the tensile strength almost remained invariant with the annealing temperature.A tensile strength of 1 537 MPa and an elong-ation of 25.1% were achieved for the 820 ℃ condition.The volume fractions of austenite and martensite were identified by X-ray diffraction.It was found that with increasing annealing temperature, the volume fraction of the retained austenite decreased, and the ductility also had a gradual downward trend.The related austenite stability was discussed here as well.展开更多
During the production of the inner walls of ovens,pit defects were formed on the surface of the enamel layer that was enameled on the cold-rolled steel via electrostatic powder spraying and sintering.The paper elabora...During the production of the inner walls of ovens,pit defects were formed on the surface of the enamel layer that was enameled on the cold-rolled steel via electrostatic powder spraying and sintering.The paper elaborates on the microstructure and element distribution of the enamel-steel interface and the enamel layer.Optical microscopy,scanning electron microscopy,and energy-dispersive spectroscopy were adopted to investigate the microstructure of a longitudinal section of the defect,and the pit-forming causes were analyzed.The results show that rusty spots lead to pit defects.During high-temperature firing,there is an inadequate fusion and reaction between iron oxides of the rusty spots and the enamel glaze.The rusty spots are closely related to pretreatment process;thus,to avoid their occurrence,electrostatic powder spraying and sintering should be performed timely after forming,degreasing,and thorough drying of the metal sheets.展开更多
After exploring the influence of stress,cold-rolling reduction and cooling rate on transforma-tion induced strain,the transformation induced superplasticity forming technique of the 18Nimaraging steel(2450 MPa)was dev...After exploring the influence of stress,cold-rolling reduction and cooling rate on transforma-tion induced strain,the transformation induced superplasticity forming technique of the 18Nimaraging steel(2450 MPa)was developed.Through 14 times γα′ cyclic transformation,thelimited elongation of 320% can be obtained in 60% cold-rolled specimen.TEM observationrevealed that the morphology of stress induced martensite is massive.展开更多
This paper introduces working principle and technical features of vacuum filter in emulsion system for tandem cold strip mill.Based on specific cases,this paper analyses and assesses the effect before and after using ...This paper introduces working principle and technical features of vacuum filter in emulsion system for tandem cold strip mill.Based on specific cases,this paper analyses and assesses the effect before and after using the emulsion system with the usage of the vacuum filter for strip mill.Compare with the effect when using the first generation vacuum filter,the emulsion quality is improved significantly by using the second generation vacuum filter,which at the same time ensures steady operation of the rolling mill and surface quality of the mill products. As a result,investment and running costs are lowered,emissions of the waste emulsion are reduced,waste water treatment costs are reduced and so as the environmental pollution.It can be seen the second generation vacuum filter has obvious economic and environmental benefits.Therefor,it suggests that the filter should be used widely in the field of automotive,environmental protection rolling steel and nonferrous metals.展开更多
It is fundamentally important to understand the influence of strain on the density of deformation twins in TWIP steel because twinning is its dominant deformation mechanism.The deformation behavior of a Fe -30Mn - 4Si...It is fundamentally important to understand the influence of strain on the density of deformation twins in TWIP steel because twinning is its dominant deformation mechanism.The deformation behavior of a Fe -30Mn - 4Si-3Al-0.097C steel has been investigated by X -ray diffraction(XRD),electron backscatter diffraction (EBSD) and transmission electron microscopy(TEM) techniques.Sample with an average grain size of 10μm was deformed in cold - rolling with a reduction of 10%,20%,30%,40%,50%,60%and 70%,respectively. The mechanical properties of the cold - rolled samples were further investigated by tensile tests.The yield strength (σy) and ultimate - tensile - strength(σUTS) of the as - prepared sample is 480 MPa and 850 MPa, respectively.However,under cold rolling deformation,the tensile strength obviously increases with an increase in rolling reduction.The sample with a rolling reduction of 10%exhibitsσy of 610 MPa andσUTS of - 1000 MPa. The yield strength and tensile strength are further enhanced up to 1320 MPa and 1 378 MPa for the specimen with a rolling reduction of 70%,regardless of the poor ductility of 6.7%.The deformation microstructures were studied by EBSD and TEM observations.It is found that,with increasing rolling reduction,the average distance between deformation twins decreases gradually while the density of deformation twins(the length of twin boundary in unit area) exhibit a maximum value at 40%cold-rolling + tension.Carefully statistics analysis reveals grain orientation is closely related to the deformation twins and the underlying mechanism governing the twinning is discussed.展开更多
In this paper,the flatness control technology AnShaperTM for cold-rolling mill and industry application are introduced.AnShaperTM includes;partitioning piezomagnetic shape meter for flatness measurement for cold-rolli...In this paper,the flatness control technology AnShaperTM for cold-rolling mill and industry application are introduced.AnShaperTM includes;partitioning piezomagnetic shape meter for flatness measurement for cold-rolling strip;flatness measured signals processing system based on digital signal processing（DSP）;flatness feedback control model system based on the control efficiency of flatness control actuators and model adaptive function.The application verifies that strip flatness can meet the need of high quality product by using AnShaperTM.The average flatness quality is about 5Ⅰ-unit and the 0.18 mm ultrathin thickness strip flatness is 10Ⅰ-unit.展开更多
FeCrAl alloy is one of the most promising candidates as an accident-tolerant fuel(ATF)cladding material.Herein,the influence of cold-rolling(CR)reduction on microstructure and tensile properties of the as-annealed FeC...FeCrAl alloy is one of the most promising candidates as an accident-tolerant fuel(ATF)cladding material.Herein,the influence of cold-rolling(CR)reduction on microstructure and tensile properties of the as-annealed FeCrAl alloys,with low Cr and Nb contents,is systematically examined.With the increase in CR reduction,the grain size of FeCrAl alloy is obviously refined after annealing because the increase in stored deformation energy leads to enhanced recrystallization.However,the large CR reductions result in a severe mixed-grain microstructure,significantly reducing the uniform deformability of the FeCrAl alloy.The dislocation density of the as-annealed FeCrAl alloy decreases with the increase in CR reduction,except for the excessive CR reduction of 50%.Moreover,the Laves phases are crushed and dissolved during CR and annealing,as well as large amounts of refined Laves phases are found after large CR reductions.The pinning effect of the Laves phases can significantly improve the strength of FeCrAl alloy.Accordingly,the strengthening mechanisms of FeCrAl alloy consist of fine-grain strengthening,dislocation strengthening and precipitation strengthening.Finally,the FeCrAl alloy,with a CR reduction of 30%,achieves optimal tensile properties.This study can provide theoretical guidance for the industrial production of the FeCrAl alloy.展开更多
Single-phase face-centered cubic(fcc)medium-and high-entropy alloys(MEAs/HEAs)have high ductility but low yield strength.In this work,the microstructures of single-phase fcc Ni_(2)CoFeV_(0.5) MEAs were tailored by col...Single-phase face-centered cubic(fcc)medium-and high-entropy alloys(MEAs/HEAs)have high ductility but low yield strength.In this work,the microstructures of single-phase fcc Ni_(2)CoFeV_(0.5) MEAs were tailored by cold-rolling and subsequent annealing and typical heterogeneous lamella(HL)structures composed of recrystallized micro-grain lamellae(with an averaged grain size of∼4μm)and nonrecrystallized nano-/ultrafine-grain lamellae were obtained.Tensile tests revealed that most HL samples exhibited excellent strength and ductility synergy.The HL sample with∼23 vol%recrystallized grains annealed at 590℃ for 1 h had a high yield strength of 1120 MPa and a good fracture elongation of 12.3%,which increased by 5%and 46%,respectively compared with those of as-rolled sample.Annealing-induced yield strength increase is attributed to high-density annealing twin boundaries(TBs)in the recrystallized grains,the annihilation of mobile dislocations inside the non-recrystallized grains,and extra heterodeformation-induced strengthening produced by the HL structure.Hall-Petch relationship of Ni_(2)CoFeV_(0.5) MEA can be reasonably described by counting both TBs and grain boundaries,with lattice friction stress of 87.3 MPa and coefficient of 722.8 MPaμm1/2.Our work provides optional and controllable solutions for preparing MEAs/HEAs with excellent mechanical properties by low-cost and high-efficiency thermomechanical treatments.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
文摘Cold-rolled advanced high-strength steel sheets have become the material of choice for the automotive industry because of their unique attributes of high strength and balanced mechanical properties.High-hydrogen gas jet cooling and water quenching are the most commonly used ultrafast cooling technologies for producing martensite-containing high-strength steel sheets.The water quenching technology ensures the fastest industrial cooling rate of 1 000 K/s;therefore,it has the highest potential with respect to saving alloys.In this study,the water quenching of a C-Mn-containing steel sheet is simulated during continuous annealing to investigate the effect of water quenching and tempering parameters on its mechanical properties.The results reveal that at low quenching temperatures,the strength of the steel sheet decreases as the soaking temperature increases.However,at high quenching temperatures,a high soaking temperature corresponds to increased strength after quenching,regardless of whether the material was austenitized in the single austenite zone or the inter-critical zone.Therefore,a high quenching temperature always results in a high strength and a high yield ratio after quenching.Low-temperature overaging(tempering) considerably influences the yield strength and yield ratio,and the extent of this influence is correlated with the soaking temperature.
文摘Cold-rolled martensitic steel sheets produced on continuous annealing lines with water quenching facility,have advantages of high strength and low alloying element contents.These are in good accordance with the trend of light-weighting and fuel saving for automotive steel.In this article,a cold-rolled martensitic steel is studied to investigate the effect of annealing parameters on its mechanical properties.It is found that the quenching temperature and the slow cooling speed as well as the overageing temperature have significant influence on the strength of the experimental steel.The temperature zone at which the austenite decomposition is slow or has not started may be chosen as the quenching temperature to ensure the steel's strength stability.The slow cooling speed also influences the steel's strength greatly.A high cooling rate will lead to significantly higher strength.Tempering would decrease the steel's tensile strength but would increase its yield strength.
文摘This study presents the fatigue response of 304 stainless steel foil, cold-rolled to a thickness of 3.2 μm with 87 percent cold work at orientations of 0, 45, and 90 degrees to the direction of rolling. Fatigue specimens were fabricated by laminating a supportive layer of 20-μm polyimide film to one side of the foil and patterning 242 crack initiation features by photolithographic process. Progression of fatigue damage was determined through electrical resistance measurement. The fatigue response was demonstrated to be largely affected by anisotropy existing between the rolling direction and the off-axis orientations. Fatigue cracks that traveled in a direction parallel to the elongated grains (cyclic loads applied at 90-degree orientation to foil rolling direction) had the most fatigue response (undesirable characteristic). The construction of the specimens with thin foil supported by a film backing contributed to high fatigue threshold.
文摘Surface defects of the cold-rolled sheets of Ti-IF steel were studied and analyzed. After analyzing surface defects of cold-rolled sheets, such as shelling defects, holes and sliver defects by SEM/EDS, a variety of inclusions were found. In addition, the distribution of macro-inclusions in slabs was analyzed by MIDAS method. The results show the macroscopic inclusion bands of head slabs and normal slabs are in 1/8 slab thickness regions of both inner arc side and outer arc side. The formation process of the defects in the cold-rolled sheets was simulated with an experimental cold-rolling machine for comparison. The results show that there were three kinds of inclusions underneath the surface defects: Al2O3, SiO2 and particles from slag entrainment, which were the main reason for defect formation during cold rolling.
基金financially supported by the National Natural Science Foundation of China(Nos.52071322 and 51771192).
文摘The objective of the present study is to develop heterogeneous microstructure in cold-rolled medium Mn steels(MMSs)annealing strategy.The cold-rolled Fe-4.7Mn-0.15C(wt%)steel is annealed twice at different temperatures to produce an ultra-fine heterogeneous microstructure with lath-shaped and granular-shaped retained austenite.Excellent mechanical behavior of significant strength enhancement with negligible ductility loss can be achieved.The high strength-ductility properties are attributed to the active transformation induced plasticity effect over a broad strain range owing to dispersive mechanical stabilities of the heterogeneous austenite.Furthermore,the typical yield point elongation phenomenon which is commonly observed in cold-rolled MMSs can be effectively reduced by this microstructural strategy.
基金Item Sponsored by National Natural Science Foundation of China(No.51174058)
文摘The thermal treatment process of cold-rolled Cu-Al composite strip under magnetic field conditions is systematically investigated by means of metallographic microscope and universal testing machine to observe the interface microstructure and test the mechanical properties.The heat treatment parameters'effects to the interface structure and mechanical properties of Al-Cu cold-rolled strip are discussed.The conclusions is showed as follows:(1)when the magnetic field intensity is greater than 0.1 T,the interface layer grow widely and stimulate the interfacial compounds'generation,the shear strength is reduced.(2)When the Cu-Al specimen's annealing temperature is at the condition of300℃,the interfacial layer narrows when the magnetic field strength stay 0.1T than that without magnetic field,the magnetic filed restrains the interfacial compounds'generation,the shear strength reaches as high as 124Mpa;(3)The interfacial compounds are meanly brittleness intermetallic compounds such as CuAl,CuAl_2,Cu_9Al_4.
文摘Texture evolution of high-manganese twining-induced plasticity (TWIP) steels (Fe-16Mn-0.6C) during cold-rolling is studied by means of quantitative orientation distribution function (ODF)analysis.Thickness reductions of the specimens during cold-rolling are 10%,20%,30%,50% and 65%,respectively.Evolution of texture is of the Brass type,which is typical for low-stacking fault energy (SFE) materials.The contribution of deformation twinning to the development of texture is clearly illustrated by the monotonic increase of the twinned Cu component.In the present study,the deformation twinning was identified as significantly contributing to deformation up to the maximum reduction applied.These results are useful for the prediction and control of the texture in TWIP steels.
文摘Many advanced technologies have been applied in developing the automatic measuring device for testing transverse thickness difference of cold-rolling steel sheet,such as the technologies of automatic control,sensor measurement,marking identification,photographic location,computer application and information transmission.This measuring device can measure the transverse thickness difference of the steel plate accurately and quickly,with a high detection level of automation.It is an effective detection equipment for transverse thickness control of steel plate.Horizontal width of steel plate measuring 0.8-1.4 m, horizontal measurement point positioning accuracy±0.02 mm,thickness range 0.2-2.0 mm, measurement accuracy within±1μm.
文摘For the purpose of developing a 1 500 MPa grade steel sheet with excellent strength and ductility, a 0.15C-10Mn-1.5Al steel was employed to study austenite stability and microstructural evolution based on a novel double annealing processing.After a conventional intercritical annealing process, the sample was heated again to a temperature higher than A_(c3) for a very short time to generate austenite grains with different manganese content;thus, the microstructure of martensite plus austenite can be obtained at room temperature.The experimental results show that with increasing annealing temperature, the tensile strength and yield strength increase.When the annealing temperature was higher than 820 ℃,the microstructure consisted of martensite plus austenite, and the tensile strength almost remained invariant with the annealing temperature.A tensile strength of 1 537 MPa and an elong-ation of 25.1% were achieved for the 820 ℃ condition.The volume fractions of austenite and martensite were identified by X-ray diffraction.It was found that with increasing annealing temperature, the volume fraction of the retained austenite decreased, and the ductility also had a gradual downward trend.The related austenite stability was discussed here as well.
文摘During the production of the inner walls of ovens,pit defects were formed on the surface of the enamel layer that was enameled on the cold-rolled steel via electrostatic powder spraying and sintering.The paper elaborates on the microstructure and element distribution of the enamel-steel interface and the enamel layer.Optical microscopy,scanning electron microscopy,and energy-dispersive spectroscopy were adopted to investigate the microstructure of a longitudinal section of the defect,and the pit-forming causes were analyzed.The results show that rusty spots lead to pit defects.During high-temperature firing,there is an inadequate fusion and reaction between iron oxides of the rusty spots and the enamel glaze.The rusty spots are closely related to pretreatment process;thus,to avoid their occurrence,electrostatic powder spraying and sintering should be performed timely after forming,degreasing,and thorough drying of the metal sheets.
文摘After exploring the influence of stress,cold-rolling reduction and cooling rate on transforma-tion induced strain,the transformation induced superplasticity forming technique of the 18Nimaraging steel(2450 MPa)was developed.Through 14 times γα′ cyclic transformation,thelimited elongation of 320% can be obtained in 60% cold-rolled specimen.TEM observationrevealed that the morphology of stress induced martensite is massive.
文摘This paper introduces working principle and technical features of vacuum filter in emulsion system for tandem cold strip mill.Based on specific cases,this paper analyses and assesses the effect before and after using the emulsion system with the usage of the vacuum filter for strip mill.Compare with the effect when using the first generation vacuum filter,the emulsion quality is improved significantly by using the second generation vacuum filter,which at the same time ensures steady operation of the rolling mill and surface quality of the mill products. As a result,investment and running costs are lowered,emissions of the waste emulsion are reduced,waste water treatment costs are reduced and so as the environmental pollution.It can be seen the second generation vacuum filter has obvious economic and environmental benefits.Therefor,it suggests that the filter should be used widely in the field of automotive,environmental protection rolling steel and nonferrous metals.
文摘It is fundamentally important to understand the influence of strain on the density of deformation twins in TWIP steel because twinning is its dominant deformation mechanism.The deformation behavior of a Fe -30Mn - 4Si-3Al-0.097C steel has been investigated by X -ray diffraction(XRD),electron backscatter diffraction (EBSD) and transmission electron microscopy(TEM) techniques.Sample with an average grain size of 10μm was deformed in cold - rolling with a reduction of 10%,20%,30%,40%,50%,60%and 70%,respectively. The mechanical properties of the cold - rolled samples were further investigated by tensile tests.The yield strength (σy) and ultimate - tensile - strength(σUTS) of the as - prepared sample is 480 MPa and 850 MPa, respectively.However,under cold rolling deformation,the tensile strength obviously increases with an increase in rolling reduction.The sample with a rolling reduction of 10%exhibitsσy of 610 MPa andσUTS of - 1000 MPa. The yield strength and tensile strength are further enhanced up to 1320 MPa and 1 378 MPa for the specimen with a rolling reduction of 70%,regardless of the poor ductility of 6.7%.The deformation microstructures were studied by EBSD and TEM observations.It is found that,with increasing rolling reduction,the average distance between deformation twins decreases gradually while the density of deformation twins(the length of twin boundary in unit area) exhibit a maximum value at 40%cold-rolling + tension.Carefully statistics analysis reveals grain orientation is closely related to the deformation twins and the underlying mechanism governing the twinning is discussed.
文摘In this paper,the flatness control technology AnShaperTM for cold-rolling mill and industry application are introduced.AnShaperTM includes;partitioning piezomagnetic shape meter for flatness measurement for cold-rolling strip;flatness measured signals processing system based on digital signal processing（DSP）;flatness feedback control model system based on the control efficiency of flatness control actuators and model adaptive function.The application verifies that strip flatness can meet the need of high quality product by using AnShaperTM.The average flatness quality is about 5Ⅰ-unit and the 0.18 mm ultrathin thickness strip flatness is 10Ⅰ-unit.
基金financially supported by the National Natural Science Foundation of China(No.52122103)the Sichuan Science and Technology Program(No.2022YFG0346).
文摘FeCrAl alloy is one of the most promising candidates as an accident-tolerant fuel(ATF)cladding material.Herein,the influence of cold-rolling(CR)reduction on microstructure and tensile properties of the as-annealed FeCrAl alloys,with low Cr and Nb contents,is systematically examined.With the increase in CR reduction,the grain size of FeCrAl alloy is obviously refined after annealing because the increase in stored deformation energy leads to enhanced recrystallization.However,the large CR reductions result in a severe mixed-grain microstructure,significantly reducing the uniform deformability of the FeCrAl alloy.The dislocation density of the as-annealed FeCrAl alloy decreases with the increase in CR reduction,except for the excessive CR reduction of 50%.Moreover,the Laves phases are crushed and dissolved during CR and annealing,as well as large amounts of refined Laves phases are found after large CR reductions.The pinning effect of the Laves phases can significantly improve the strength of FeCrAl alloy.Accordingly,the strengthening mechanisms of FeCrAl alloy consist of fine-grain strengthening,dislocation strengthening and precipitation strengthening.Finally,the FeCrAl alloy,with a CR reduction of 30%,achieves optimal tensile properties.This study can provide theoretical guidance for the industrial production of the FeCrAl alloy.
基金supported by the National Key R&D Program of China(Grant No.2021YFA1200203)National Natural Science Foundation of China(Grant Nos.51971112,51225102,92163215,52174364,52101143,51731006,and 12202201)+1 种基金Natural Science Foundation of Jiangsu Province Major Project(Grant No.BK20212009)the Fundamental Research Funds for the Central Universities(Grant Nos.30922010202,30922010711,and 30919011405)。
文摘Single-phase face-centered cubic(fcc)medium-and high-entropy alloys(MEAs/HEAs)have high ductility but low yield strength.In this work,the microstructures of single-phase fcc Ni_(2)CoFeV_(0.5) MEAs were tailored by cold-rolling and subsequent annealing and typical heterogeneous lamella(HL)structures composed of recrystallized micro-grain lamellae(with an averaged grain size of∼4μm)and nonrecrystallized nano-/ultrafine-grain lamellae were obtained.Tensile tests revealed that most HL samples exhibited excellent strength and ductility synergy.The HL sample with∼23 vol%recrystallized grains annealed at 590℃ for 1 h had a high yield strength of 1120 MPa and a good fracture elongation of 12.3%,which increased by 5%and 46%,respectively compared with those of as-rolled sample.Annealing-induced yield strength increase is attributed to high-density annealing twin boundaries(TBs)in the recrystallized grains,the annihilation of mobile dislocations inside the non-recrystallized grains,and extra heterodeformation-induced strengthening produced by the HL structure.Hall-Petch relationship of Ni_(2)CoFeV_(0.5) MEA can be reasonably described by counting both TBs and grain boundaries,with lattice friction stress of 87.3 MPa and coefficient of 722.8 MPaμm1/2.Our work provides optional and controllable solutions for preparing MEAs/HEAs with excellent mechanical properties by low-cost and high-efficiency thermomechanical treatments.
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.
