Rolled Mg-Al-Sn series alloys generally possess limited formability due to the formation of strong basal texture.Texture weakening is an effective way to enhance formability,but usually accompanied with decreasing str...Rolled Mg-Al-Sn series alloys generally possess limited formability due to the formation of strong basal texture.Texture weakening is an effective way to enhance formability,but usually accompanied with decreasing strength.In this work,synergistic enhancement of strength and formability is achieved in a Mg-3Al-1Sn-0.5Ca-0.1Sm(ATXS3110)alloy by 0.2 wt.%Mn addition combined with high temperature rolling,exhibiting a high index Erichsen(I.E.)value of~8.1 mm and near-isotropic mechanical properties.On one hand,after Mn addition,the grain refinement from~7.6μm to~4.1μm results in suppression of extension twinning,thereby preventing the development of strong basal texture upon stretch forming.On the other hand,trace Mn addition narrows the grain size distribution and promotes the formation of uniform fine grains,which induces homogeneous deformation during stretch forming.Moreover,grain refinement and high-density nano-sized precipitates caused by trace Mn addition increase the strength.This work may provide insights into designing low-cost Mg-Al-Sn series alloys with superior comprehensive mechanical properties for further structural applications.展开更多
In this work,a good balance of strength and ductility(a yield strength of 185 MPa and a uniform elongation of 20%)has been obtained in a dilute Mg-1.8Zn-0.3Y-0.3Ca-0.3Zr(wt.%)alloy using hard plate rolling(HPR)followe...In this work,a good balance of strength and ductility(a yield strength of 185 MPa and a uniform elongation of 20%)has been obtained in a dilute Mg-1.8Zn-0.3Y-0.3Ca-0.3Zr(wt.%)alloy using hard plate rolling(HPR)followed by annealing,with a low anisotropy in mechanical properties.More importantly,the HPR-annealed alloy shows an excellent formability at the same time,i.e.,the index Erichsen(I.E.)value reaches 7.9 mm(the Erichsen cupping test)at room temperature,which is higher compared with the Mg-1.8Zn-0.3Y-0.3Ca0.3Zr alloy produced by conventional multi-pass rolling(CR)followed by annealing.The excellent synergy of strength and formability of the HPR-annealed alloy is mainly attributed to a weak elliptical ring texture,as well as finer and denser Zn_(2)Zr_(3)precipitates.The formation of weak elliptical ring texture is related to the preferential co-segregation of Zn and Ca elements at boundaries of basal grains with smal misorientation angles during annealing,which inhibits the growth of basal grains and promotes the preferential growth of non-basal grains At the same time,in comparison with the CR-annealed alloy,the HPR-annealed alloy contains finer and denser Zn_(2)Zr_(3)precipitates that ar less likely to become sources of cracks,leading to the higher strength and formability of the HPR-annealed alloy.The results in this work can provide reference for the development of high strength Mg alloy sheets with excellent room temperature formability,which also shed light on mitigating planar anisotropy in mechanical properties for Mg alloy sheets.展开更多
In the present study,two-layered stainless steel-copper composites with a thickness of 50μm were initially subjected to annealing at 800,900 and 1000℃for 5 min,respectively,to achieve diverse microstructural feature...In the present study,two-layered stainless steel-copper composites with a thickness of 50μm were initially subjected to annealing at 800,900 and 1000℃for 5 min,respectively,to achieve diverse microstructural features.Then the influence of annealing temperature on the formability of stainless steel-copper composites and the quality of micro composite cups manufactured by micro deep drawing(MDD)were investigated,and the underlying mechanism was analyzed.Three finite element(FE)models,including basic FE model,Voronoi FE model and surface morphological FE model,were developed to analyze the forming performance of stainless steel-copper composites during MDD.The results show that the stainless steel-copper composites annealed at 900℃possess the best plasticity owing to the homogeneous and refined microstructure in both stainless steel and copper matrixes,and the micro composite cup with specimen annealed at 900℃exhibits a uniform wall thickness as well as high surface quality with the fewest wrinkles.The results obtained from the surface morphological FE model considering material inhomogeneity and surface morphology of the composites are the closest to the experimental results compared to the basic and Voronoi FE model.During MDD process,the drawing forces decrease with increasing annealing temperature as a consequence of the strength reduction.展开更多
This study involved the development of an interpretable prediction framework to access the stretch formability of AZ31 magnesium alloys through the combination of the extreme gradient boosting(XGBoost)model with the s...This study involved the development of an interpretable prediction framework to access the stretch formability of AZ31 magnesium alloys through the combination of the extreme gradient boosting(XGBoost)model with the sparrow search algorithm(SSA).Eleven features were extracted from the microstructures(e.g.,grain size(GS),maximum pole intensity(I_(max)),degree of texture dispersion(μ),radius of maximum pole position(r),and angle of maximum pole position(A)),mechanical properties(e.g.,tensile yield strength(TYS),ultimate tensile strength(UTS),elongation-to-failure(EL),and strength difference(∆S))and test conditions(e.g.,sheet thickness(t)and punch speed(v))in the data collected from the literature and experiments.Pearson correlation coefficient and exhaustive screening methods identified ten key features(not including UTS)as the final inputs,and they enhanced the prediction accuracy of Index Erichsen(IE),which served as the model’s output.The newly developed SSA-XGBoost model exhibited an improved prediction performance,with a goodness of fit(R^(2))of 0.91 compared with traditional machine learning models.A new dataset(four samples)was prepared to validate the reliability and generalization capacity of this model,and below 5%errors were observed between predicted and experimental IE values.Based on this result,the quantitative relationship between the key features and IE values was established via Shapley additive explanation method and XGBoost feature importance analysis.I_(max),TYS,EL,r,GS,andΔS showed a crucial influence on the IE of 10 input features.This work offers a reliable and accurate tool for the prediction of the stretch formability of AZ31 magnesium alloys and provides insights into the development of high-formable magnesium alloys.展开更多
The microstructure and properties of a 1030B Al strip were improved by applying ultrasonic melt treatment(UMT)in a Hazelett continuous casting direct rolling production line.The microstructure and properties of the 10...The microstructure and properties of a 1030B Al strip were improved by applying ultrasonic melt treatment(UMT)in a Hazelett continuous casting direct rolling production line.The microstructure and properties of the 1030B Al strip were investigated by scanning electron microscopy,electron backscatter diffraction,and tensile testing.Applying UMT reduced the average grain size of the as-cast sheet by more than 28.0%with respect to that of the normal samples without UMT.When UMT was applied,the rolled strip inherited the refined grains from the as-cast sheet with an average grain size smaller than 63.0μm.Meanwhile,the dislocation density was increased by the grain refinement,dynamic recovery,and recrystallization during rolling.Accordingly,the strain-hardening rates of the rolled samples after UMT were generally higher than those of the normal samples,and the strength of the rolled strip was also improved.Furthermore,the rolled strip exhibited better formability with higher strain-hardening exponents and Erichsen index values.展开更多
This work investigates how temperature and microstructural evolution affect the formability of face-centered cubic(fcc)structured CoCrFeNiMn_(0.75)Cu_(0.25) high entropy alloy(HEA)sheets under complex stress condition...This work investigates how temperature and microstructural evolution affect the formability of face-centered cubic(fcc)structured CoCrFeNiMn_(0.75)Cu_(0.25) high entropy alloy(HEA)sheets under complex stress conditions.Erichsen cupping tests were conducted to quantitatively evaluate the deformation capacity at room temperature(298 K)and cryogenic temperatures.The findings reveal a strong temperature dependence on the formability of the HEA.A decrease in the deformation temperature from 298 to 93 K causes a significant increase in both the Erichsen index(IE)(from 9.8 to 12.4 mm)and the expansion rate(δ)of surface area(from 51.6%to 76.3%),as well as a reduction in the average deviation(η)of thickness(from 55.1%to 44.4%),signifying its ultrahigh formability and uniform deformation capability at cryogenic temperature.This enhancement is attributed to the transition in the deformation mechanism from single dislocation slip at 298 K to a cooperative of plastic deformation mechanisms at 93 K,involving dislocation slip,stacking faults(SFs),Lomer-Cottrell(L-C)locks and multi-scale nanotwins.The lower stacking fault energy of the alloy facilitates these deformation mechanisms,particularly the formation of SFs and nanotwins,which enhance ductility and strength by providing additional pathways for plastic deformation.These mechanisms collectively contribute to delaying plastic instability,thereby improving the overall formability.This work provides a comprehensive understanding of the underlying reasons for the enhanced formability of HEAs at cryogenic temperatures,offering valuable insights for their practical use in challenging environments.展开更多
Poor formability is a key problem that limits the application of flame-retardant Mg-Al-Ca based alloys at room temperature.In this study,we present a new Mg-6Al-3Ca-0.4Mn-2Zn(wt%)alloy which exhibits excellent flame-r...Poor formability is a key problem that limits the application of flame-retardant Mg-Al-Ca based alloys at room temperature.In this study,we present a new Mg-6Al-3Ca-0.4Mn-2Zn(wt%)alloy which exhibits excellent flame-retardant performance and excellent formability.Due to the high Ca content,the Mg-6Al-3Ca-0.4Mn-2Zn(wt%)alloy does not burn at 1065℃.The formability of the alloys is measured using a three-point bending test,and the Mg-6Al-3Ca-0.4Mn-2Zn(wt%)alloy shows excellent formability,with a significant increase in bending displacement from 7.1 mm to 23.8 mm compared to the Mg-6Al-3Ca-0.4Mn(wt%)alloy.The combined effect of the weakened basal texture,the reduction of twins and the plastically deformable Al2Ca phase particles ensures good formability of the Mg-6Al-3Ca-0.4Mn-2Zn(wt%)alloy.The dynamic recrystallization mechanisms of the alloys have been analyzed,and the promotion of dynamic recrystallization by the PSN mechanism is responsible for the weakened basal texture and the reduction of twins in the Mg-6Al-3Ca-0.4Mn-2Zn(wt%)alloy.The new Mg alloy is attractive for industrial applications due to its excellent flame-retardant performance and formability.展开更多
The effects of Al(Fe,Mn)Si particles controlled by different hot-rolling deformations on the microstructure evolution,texture evolution,and formabilities of Al−Mg−Si−Zn alloy were systematically investigated using OM,...The effects of Al(Fe,Mn)Si particles controlled by different hot-rolling deformations on the microstructure evolution,texture evolution,and formabilities of Al−Mg−Si−Zn alloy were systematically investigated using OM,SEM,TEM,XRD,and tensile tests.The results indicate that Al(Fe,Mn)Si particles with different size and number distribution characteristics can be obtained by adjusting the hot-rolling deformation degree(59%,74%and 87%),and these differences in particle distribution are the main factors affecting the recrystallization nucleation and grain growth during solution treatment.After T4P treatment,the grain orientations in the Al−Mg−Si−Zn alloy sheets with 59%and 74%hot-rolling deformation tend to be randomly distributed.In comparison,the sheet with 87%hot-rolling deformation consists of R{124}<211>,CubeND{100}<013>,Copper{112}<111>and Brass{011}<211>texture components.The medium size and number of Al(Fe,Mn)Si particles obtained at 74%hot-rolling deformation cause fine grains and randomly distributed texture,which significantly improves the formability of Al−Mg−Si−Zn alloy.展开更多
In recent years,modification of texture distribution has been considered a valid approach to improve the room-temperature(RT)formability of magnesium(Mg)alloys.In this study,a novel Mgsingle bond2Znsingle bond3Lisingl...In recent years,modification of texture distribution has been considered a valid approach to improve the room-temperature(RT)formability of magnesium(Mg)alloys.In this study,a novel Mgsingle bond2Znsingle bond3Lisingle bond1Gd alloy sheet with weak elliptical-texture was fabricated by cold rolling and subsequent annealing,and it showed an excellent Erichsen(IE)value near 7.1 mm.Both quasi-in-situ electron backscatter diffraction(EBSD)and transmission electron microscopy(TEM)analysis indicate that considerable basal and pyramidal dislocations can be activated in the cold rolling process.During annealing,these dislocations can induce nucleation and then cause preferential misorientation relationships around〈uvt0〉concerning the nuclei and parent grains,which can facilitate the formation of elliptical texture.Furthermore,the particle-stimulated nucleation(PSN)mechanism and the co-segregation of Zn and Gd at grain boundaries(GB)further weak texture intensity.Finally,the mechanical properties of the Mgsingle bond2Znsingle bond3Lisingle bond1Gd alloy sheet are significantly improved.展开更多
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
As a cathode material for thermal batteries,NiS_(2)has a high theoretical capacity but low thermal stability.Besides,the poor formability of NiS_(2)powders also restricts the cathode performance of thermal batteries.I...As a cathode material for thermal batteries,NiS_(2)has a high theoretical capacity but low thermal stability.Besides,the poor formability of NiS_(2)powders also restricts the cathode performance of thermal batteries.In this paper,the novel NiS_(2)/SiO_(2)composite material was developed by high temperature vulcanization to improve the thermal stability formability of NiS_(2).The good filling and lubrication of spherical SiO_(2)can improve the thermal conductivity of NiS_(2)electrode.The discharge test shows that the NiS_(2)/SiO_(2)cathode has a stable discharge voltage at a current density of 200 mA/cm^(2),and the activation time is shortened by nearly 20%compared with the NiS_(2)cathode.In addition,due to the favorable thermal insulation protection of SiO_(2),the initial decomposition temperature of NiS_(2)is increased by 30℃after the addition of SiO_(2).The incorporation of SiO_(2)not only effectively improves the thermal stability and electrochemical properties of NiS_(2),but also improves the cold pressing forming performance of the NiS_(2)powder.Therefore,the novel NiS_(2)/SiO_(2)composite material is more suitable for thermal batteries with high stability and fast response,which is of great significance for improving the maneuverability and quality reliability of weapons and equipment.展开更多
In this study,the effects of pre-strain-induced tensile twins(TTWs)and controlled heat treatment on the formability behavior of AZX311 Mg alloy sheets were investigated.A 4%compressive strain was applied to pre-strain...In this study,the effects of pre-strain-induced tensile twins(TTWs)and controlled heat treatment on the formability behavior of AZX311 Mg alloy sheets were investigated.A 4%compressive strain was applied to pre-strain the sheets using the in-plane compression(IPC)technique along the rolling direction(RD)to introduce TTWs.The pre-strained(PS)samples were subsequently heat-treated at 250℃,350℃,and 400℃ independently for 1 hr,and are termed as PSA1,PSA2,and PSA3,respectively.Erichsen cupping tests were conducted to assess the formability of the sheet samples under different initial conditions.The results showed that the PS sample heat-treated at 250℃ for 1hr exhibited a decrease in the Erichsen index(IE)compared to the as-rolled sample,whereas PSA2 and PSA3 samples showed an increase in IE values.Microtexture analysis revealed that most of the TTWs generated through pre-twinning were stable at 250℃;however,the twin volume fraction reduced to 41%at 350℃ compared to the PS samples due to enhanced thermal activity at that temperature.Furthermore,PSA2 samples showed severe grain coarsening in some areas of the sample,and the fraction of such grains increased in the PSA3 samples.The stretch formability(IE value)of PSA2 samples showed a 32.3%increase compared to the as-rolled specimens.Additionally,the analysis of the deformed specimen at failure under the Erichsen test indicated that considerable detwinning occurs in the PS and PSA1 samples,whereas dislocation slip activity dominates in the PSA2 and PSA3 samples during stretch forming.Apart from detwinning and dislocation slip,deformation twins were also observed in all samples after the Erichsen test.Thus,this work highlights the importance of texture control and its underlying mechanisms via pre-twinning followed by heat treatment and their impact on the room temperature(RT)stretch formability of AZX311 Mg alloy sheets.展开更多
The influences of strength coefficient K, work hardening exponent n and thickness t of the overlapping sheet on bulging process are analyzed based on hardening material model. Also, bulging experiments are carried out...The influences of strength coefficient K, work hardening exponent n and thickness t of the overlapping sheet on bulging process are analyzed based on hardening material model. Also, bulging experiments are carried out by taking the aluminum alloy LF21 as formed sheet metal, and selecting overlapping sheet with different thicknesses and material properties, by which accuracy of the above analysis result is verified in the aspects of geometric shape, thickness distribution and limit bulging height. The results show that higher strength coefficient K, larger work hardening exponent n and proper thickness of the overlapping sheet are helpful to improve the formability and forming uniformity of formed sheet metal.展开更多
The effect of the repeated unidirectional bending （RUB） process and annealing on the formability of magnesium alloy sheets was investigated. The RUB process and annealing treatments produce two effects on microstruc...The effect of the repeated unidirectional bending （RUB） process and annealing on the formability of magnesium alloy sheets was investigated. The RUB process and annealing treatments produce two effects on microstructure： grain coarsening and weakening of the texture. The sheet that underwent RUB and was annealed at 300 ℃exhibits the best formability owing to the reduction of the （0002） basal texture intensity, which results in low yield strength, large fracture elongation, small Lankford value （r-value） and large strain hardening exponent （n-value）. Compared with the as-received sheet, the coarse-grain sheet produced by RUB and annealing at 400 ℃ exhibits lower tensile properties but higher formability. The phenomenon is because the deformation twin enhanced by grain coarsening can accommodate the strain of thickness.展开更多
The effects of strain rate on microstructure and formability of AZ31B magnesium alloy sheets were investigated through uniaxial tensile tests and hemispherical punch tests with strain rates of 10^-4, 10^-3, 10^-2, 10^...The effects of strain rate on microstructure and formability of AZ31B magnesium alloy sheets were investigated through uniaxial tensile tests and hemispherical punch tests with strain rates of 10^-4, 10^-3, 10^-2, 10^-1 s^-1 at 200℃. The results show that the volume fraction of dynamic recrystallization grains increases and the original grains are gradually replaced by recrystallization grains with the strain rate decreasing. A larger elongation and a smaller r-value are obtained at a lower strain rate, moreover the erichsen values become larger with the strain rate reducing, so the formability improves. This problem arises in part from the enhanced softening and the coordination of recrystallization grains during deformation.展开更多
Flow behavior of the Al-Si coated boron steel was investigated with Gleeble-3500,in comparison with the uncoated one.Effect of deformation conditions on the coating integrity was characterized by optical microscopy.Fa...Flow behavior of the Al-Si coated boron steel was investigated with Gleeble-3500,in comparison with the uncoated one.Effect of deformation conditions on the coating integrity was characterized by optical microscopy.Facture surfaces of the coated steels were inspected under SEM.Experimental results indicate that the ultimate tensile strength and ductility of the Al-Si coated boron steel are lower than those of the uncoated steel under test conditions.Extensive cracks occur in the coating after tensile tests;the width and density of cracks are sensitive to the deformation temperatures and strain rates.The bare substrate exposed between the separate coating segments is oxidized.Appearance of the oxide degrades the Al-Si coating adhesion.Remarkable difference between formability of the coating layer and the substrate is confirmed.The formability of the Al-Si coating could be optimized by controlling the phase transformation of the ductile Fe-rich intermetallic compounds within it during the austenization.展开更多
Ring hoop tension test and tube bulging test were carried out at elevated temperatures up to 480 ℃to evaluate the formability of AZ31B extruded tube for internal high pressure forming （IHPF） process. The total elon...Ring hoop tension test and tube bulging test were carried out at elevated temperatures up to 480 ℃to evaluate the formability of AZ31B extruded tube for internal high pressure forming （IHPF） process. The total elongation along hoop direction and the maximum expansion ratio （MER） of the tube were obtained. The fracture surface after bursting was also analyzed. The results show that the total elongation along hoop direction and the MER value have a similar changing tendency as the testing temperature increases, which is quite different from the total elongation along axial direction. Both the total elongation along hoop direction and the MER value increase to a peak value at about 160 ℃. After that, they begin to decrease quickly until a certain rebounding temperature is reached. From the rebounding temperature, they begin to increase rapidly again. Burnt structure appears on the fracture surface when tested at temperatures higher than 420 ℃. Therefore, the forming temperature of the tested tube should be lower than 420 ℃, even though bigger formability can be achieved at higher temperature.展开更多
The formability of AA5052/polyethylene/AA5052 sandwich sheets was experimentally studied. Three kinds of AA5052/polyethylene/AA5052 sandwich specimens with different thicknesses of core materials were prepared by the ...The formability of AA5052/polyethylene/AA5052 sandwich sheets was experimentally studied. Three kinds of AA5052/polyethylene/AA5052 sandwich specimens with different thicknesses of core materials were prepared by the hot pressing adhesive method. Then, the uniaxial tensile tests were conducted to investigate the mechanical properties of AA5052/polyethylene/ AA5052 sandwich sheets, and the stretching tests were carried out to investigate the influences of polymer core thickness on the limit dome height of the sandwich sheet. The forming limit curves for three kinds of sandwich sheets were obtained. The experimental results show that the forming limit of the AA5052/polyethylene/AA5052 sandwich sheet is higher than that of the monolithic AA5052 sheet, and it increases with increasing the thickness of polyethylene core.展开更多
Experimental study has been conducted for an interstitial free(IF) sheet steel on its surface roughness evolution and formability with respect to grain size and sheet thickness effect. The surface roughness of IF she...Experimental study has been conducted for an interstitial free(IF) sheet steel on its surface roughness evolution and formability with respect to grain size and sheet thickness effect. The surface roughness of IF sheet steel is proportional to effective strain, grain size and inversely proportional to sheet thickness; the larger grain reduces the formability by accelerating the surface roughening rate and enhance formability by raising the workhardening rate, while the latter effect plays the dominate role. The grain size effect on surface roughening and formability is more obvious when the sheets are thinner.展开更多
Aluminum alloy （Al-alloy） thin-walled （D/t ＆gt; 20, diameter D, wall thickness t） bent tubes have attracted increasing applications in many industries with mass quantities and diverse specifications due to satisf...Aluminum alloy （Al-alloy） thin-walled （D/t ＆gt; 20, diameter D, wall thickness t） bent tubes have attracted increasing applications in many industries with mass quantities and diverse specifications due to satisfying high strength to weigh ratio requirements of product manufacturing. However, due to nonlinear nature of bending with coupling effects of multiple factors, the similarity theory seems not applicable and there occurs a challenge for efficient and reliable evaluation of the bending formability of thin-walled tube with various bending specifications. Considering the unequal deformation and three major instabilities, the bending formability of thin-walled Al-alloy tube in changing tube sizes such as D and t are clarified via both the analytical and FE modeling/ simulations. The experiments of rotary draw bending are conducted to validate the theoretical models and further confirm ＇size effect＇ related bending formability. The major results show that （1） The anti-wrinkling capability of tube decreases with the larger D and smaller t, and the effect significance of t is larger than that of D even under rigid supports; （2） The wall thinning increases with the larger D and smaller t, and this tendency becomes much more obvious under rigid supports; （3） The cross-section deformation increases with the larger D and smaller t according to the analytical model obtained intrinsic relationship, while this tendency becomes opposite due to the nonlinear role of mandrel die; （4） The size factor D/t can be used as a nondimensional index to evaluate both the bending formability regarding the wall thinning and cross-section deformation.展开更多
基金supported by The National Natural Science Foundation of China(under Nos.52234009,U19A2084,52171116,U22A20109,52201113)Partial financial support came from Program for the Central University Youth Innovation Team(419021423505)+2 种基金the Fundamental Research Funds for the Central Universities(No.2412022QD037)the Excellent Youth Program of Jilin Provincial Department of Education(JJKH20241425KJ)the Fundamental Research Funds for the Central Universities,JLU.
文摘Rolled Mg-Al-Sn series alloys generally possess limited formability due to the formation of strong basal texture.Texture weakening is an effective way to enhance formability,but usually accompanied with decreasing strength.In this work,synergistic enhancement of strength and formability is achieved in a Mg-3Al-1Sn-0.5Ca-0.1Sm(ATXS3110)alloy by 0.2 wt.%Mn addition combined with high temperature rolling,exhibiting a high index Erichsen(I.E.)value of~8.1 mm and near-isotropic mechanical properties.On one hand,after Mn addition,the grain refinement from~7.6μm to~4.1μm results in suppression of extension twinning,thereby preventing the development of strong basal texture upon stretch forming.On the other hand,trace Mn addition narrows the grain size distribution and promotes the formation of uniform fine grains,which induces homogeneous deformation during stretch forming.Moreover,grain refinement and high-density nano-sized precipitates caused by trace Mn addition increase the strength.This work may provide insights into designing low-cost Mg-Al-Sn series alloys with superior comprehensive mechanical properties for further structural applications.
基金Tral Science Foundation of China(Nos.52271103,52334010and 52271031)Partial financial support came from JilinScientific and Technological Development Program(No.20220301026GX)Program for the Central UniversityYouth Innovation Team。
文摘In this work,a good balance of strength and ductility(a yield strength of 185 MPa and a uniform elongation of 20%)has been obtained in a dilute Mg-1.8Zn-0.3Y-0.3Ca-0.3Zr(wt.%)alloy using hard plate rolling(HPR)followed by annealing,with a low anisotropy in mechanical properties.More importantly,the HPR-annealed alloy shows an excellent formability at the same time,i.e.,the index Erichsen(I.E.)value reaches 7.9 mm(the Erichsen cupping test)at room temperature,which is higher compared with the Mg-1.8Zn-0.3Y-0.3Ca0.3Zr alloy produced by conventional multi-pass rolling(CR)followed by annealing.The excellent synergy of strength and formability of the HPR-annealed alloy is mainly attributed to a weak elliptical ring texture,as well as finer and denser Zn_(2)Zr_(3)precipitates.The formation of weak elliptical ring texture is related to the preferential co-segregation of Zn and Ca elements at boundaries of basal grains with smal misorientation angles during annealing,which inhibits the growth of basal grains and promotes the preferential growth of non-basal grains At the same time,in comparison with the CR-annealed alloy,the HPR-annealed alloy contains finer and denser Zn_(2)Zr_(3)precipitates that ar less likely to become sources of cracks,leading to the higher strength and formability of the HPR-annealed alloy.The results in this work can provide reference for the development of high strength Mg alloy sheets with excellent room temperature formability,which also shed light on mitigating planar anisotropy in mechanical properties for Mg alloy sheets.
基金Projects(51975398,52105392)supported by the National Natural Science Foundation of ChinaProject(YDZJSX2021A006)supported by the Central Government Guided Local Science and Technology Development Fund Project,China+1 种基金Project(20210035)supported by the Scientific Activities of Selected Returned Overseas Professionals in Shanxi Province,ChinaProject(2020-037)supported by the Fund Program for the Research Project Supported by Shanxi Scholarship Council,China。
文摘In the present study,two-layered stainless steel-copper composites with a thickness of 50μm were initially subjected to annealing at 800,900 and 1000℃for 5 min,respectively,to achieve diverse microstructural features.Then the influence of annealing temperature on the formability of stainless steel-copper composites and the quality of micro composite cups manufactured by micro deep drawing(MDD)were investigated,and the underlying mechanism was analyzed.Three finite element(FE)models,including basic FE model,Voronoi FE model and surface morphological FE model,were developed to analyze the forming performance of stainless steel-copper composites during MDD.The results show that the stainless steel-copper composites annealed at 900℃possess the best plasticity owing to the homogeneous and refined microstructure in both stainless steel and copper matrixes,and the micro composite cup with specimen annealed at 900℃exhibits a uniform wall thickness as well as high surface quality with the fewest wrinkles.The results obtained from the surface morphological FE model considering material inhomogeneity and surface morphology of the composites are the closest to the experimental results compared to the basic and Voronoi FE model.During MDD process,the drawing forces decrease with increasing annealing temperature as a consequence of the strength reduction.
基金funded by the National Natural Science Foundation of China(No.52204407)the Natural Science Foundation of Jiangsu Province,China(No.BK20220595)+1 种基金the China Postdoctoral Science Foundation(No.2022M 723689)the Postgraduate Research&Practice Innovation Program of Jiangsu Province,China(No.SJCX23_1913).
文摘This study involved the development of an interpretable prediction framework to access the stretch formability of AZ31 magnesium alloys through the combination of the extreme gradient boosting(XGBoost)model with the sparrow search algorithm(SSA).Eleven features were extracted from the microstructures(e.g.,grain size(GS),maximum pole intensity(I_(max)),degree of texture dispersion(μ),radius of maximum pole position(r),and angle of maximum pole position(A)),mechanical properties(e.g.,tensile yield strength(TYS),ultimate tensile strength(UTS),elongation-to-failure(EL),and strength difference(∆S))and test conditions(e.g.,sheet thickness(t)and punch speed(v))in the data collected from the literature and experiments.Pearson correlation coefficient and exhaustive screening methods identified ten key features(not including UTS)as the final inputs,and they enhanced the prediction accuracy of Index Erichsen(IE),which served as the model’s output.The newly developed SSA-XGBoost model exhibited an improved prediction performance,with a goodness of fit(R^(2))of 0.91 compared with traditional machine learning models.A new dataset(four samples)was prepared to validate the reliability and generalization capacity of this model,and below 5%errors were observed between predicted and experimental IE values.Based on this result,the quantitative relationship between the key features and IE values was established via Shapley additive explanation method and XGBoost feature importance analysis.I_(max),TYS,EL,r,GS,andΔS showed a crucial influence on the IE of 10 input features.This work offers a reliable and accurate tool for the prediction of the stretch formability of AZ31 magnesium alloys and provides insights into the development of high-formable magnesium alloys.
基金the National Natural Science Foundation of China(No.52004254)the Major Science and Technology Project of Henan Province,China(No.221100240300).
文摘The microstructure and properties of a 1030B Al strip were improved by applying ultrasonic melt treatment(UMT)in a Hazelett continuous casting direct rolling production line.The microstructure and properties of the 1030B Al strip were investigated by scanning electron microscopy,electron backscatter diffraction,and tensile testing.Applying UMT reduced the average grain size of the as-cast sheet by more than 28.0%with respect to that of the normal samples without UMT.When UMT was applied,the rolled strip inherited the refined grains from the as-cast sheet with an average grain size smaller than 63.0μm.Meanwhile,the dislocation density was increased by the grain refinement,dynamic recovery,and recrystallization during rolling.Accordingly,the strain-hardening rates of the rolled samples after UMT were generally higher than those of the normal samples,and the strength of the rolled strip was also improved.Furthermore,the rolled strip exhibited better formability with higher strain-hardening exponents and Erichsen index values.
基金supported by the National Natural Science Foundation of China(Nos.52371025 and 52371106)Guangdong Major Project of Basic and Applied Basic Research(No.2020B0301030001)Shenzhen Fund 2021 Basic Research General Programme(No.JCYJ20210324115400002).
文摘This work investigates how temperature and microstructural evolution affect the formability of face-centered cubic(fcc)structured CoCrFeNiMn_(0.75)Cu_(0.25) high entropy alloy(HEA)sheets under complex stress conditions.Erichsen cupping tests were conducted to quantitatively evaluate the deformation capacity at room temperature(298 K)and cryogenic temperatures.The findings reveal a strong temperature dependence on the formability of the HEA.A decrease in the deformation temperature from 298 to 93 K causes a significant increase in both the Erichsen index(IE)(from 9.8 to 12.4 mm)and the expansion rate(δ)of surface area(from 51.6%to 76.3%),as well as a reduction in the average deviation(η)of thickness(from 55.1%to 44.4%),signifying its ultrahigh formability and uniform deformation capability at cryogenic temperature.This enhancement is attributed to the transition in the deformation mechanism from single dislocation slip at 298 K to a cooperative of plastic deformation mechanisms at 93 K,involving dislocation slip,stacking faults(SFs),Lomer-Cottrell(L-C)locks and multi-scale nanotwins.The lower stacking fault energy of the alloy facilitates these deformation mechanisms,particularly the formation of SFs and nanotwins,which enhance ductility and strength by providing additional pathways for plastic deformation.These mechanisms collectively contribute to delaying plastic instability,thereby improving the overall formability.This work provides a comprehensive understanding of the underlying reasons for the enhanced formability of HEAs at cryogenic temperatures,offering valuable insights for their practical use in challenging environments.
基金supported by the National Key Research and Development Program of China(No.2021YFB3701100)the Applied Basic Research Program Project of Liaoning Province of China(No.2023020253-JH2/1016)the Key Research and Development Plan of Shanxi Province(No.202102050201005)。
文摘Poor formability is a key problem that limits the application of flame-retardant Mg-Al-Ca based alloys at room temperature.In this study,we present a new Mg-6Al-3Ca-0.4Mn-2Zn(wt%)alloy which exhibits excellent flame-retardant performance and excellent formability.Due to the high Ca content,the Mg-6Al-3Ca-0.4Mn-2Zn(wt%)alloy does not burn at 1065℃.The formability of the alloys is measured using a three-point bending test,and the Mg-6Al-3Ca-0.4Mn-2Zn(wt%)alloy shows excellent formability,with a significant increase in bending displacement from 7.1 mm to 23.8 mm compared to the Mg-6Al-3Ca-0.4Mn(wt%)alloy.The combined effect of the weakened basal texture,the reduction of twins and the plastically deformable Al2Ca phase particles ensures good formability of the Mg-6Al-3Ca-0.4Mn-2Zn(wt%)alloy.The dynamic recrystallization mechanisms of the alloys have been analyzed,and the promotion of dynamic recrystallization by the PSN mechanism is responsible for the weakened basal texture and the reduction of twins in the Mg-6Al-3Ca-0.4Mn-2Zn(wt%)alloy.The new Mg alloy is attractive for industrial applications due to its excellent flame-retardant performance and formability.
基金the National Key R&D Program of China(Nos.2020YFF0218200,2016YFB0300802)for financial support。
文摘The effects of Al(Fe,Mn)Si particles controlled by different hot-rolling deformations on the microstructure evolution,texture evolution,and formabilities of Al−Mg−Si−Zn alloy were systematically investigated using OM,SEM,TEM,XRD,and tensile tests.The results indicate that Al(Fe,Mn)Si particles with different size and number distribution characteristics can be obtained by adjusting the hot-rolling deformation degree(59%,74%and 87%),and these differences in particle distribution are the main factors affecting the recrystallization nucleation and grain growth during solution treatment.After T4P treatment,the grain orientations in the Al−Mg−Si−Zn alloy sheets with 59%and 74%hot-rolling deformation tend to be randomly distributed.In comparison,the sheet with 87%hot-rolling deformation consists of R{124}<211>,CubeND{100}<013>,Copper{112}<111>and Brass{011}<211>texture components.The medium size and number of Al(Fe,Mn)Si particles obtained at 74%hot-rolling deformation cause fine grains and randomly distributed texture,which significantly improves the formability of Al−Mg−Si−Zn alloy.
基金supports from the National Natural Science Foundation of China(51901204,52161023,52271249)Science and Technology project of Yunnan Precious Metal Laboratory(YPML-2023050208)+1 种基金Yunnan Science and Technology Planning Project(202201AU070010,202301AT070276,202302AB080008,202303AA080001)supported by Yunnan Key Laboratory of Electromagnetic Materials and Devices.
文摘In recent years,modification of texture distribution has been considered a valid approach to improve the room-temperature(RT)formability of magnesium(Mg)alloys.In this study,a novel Mgsingle bond2Znsingle bond3Lisingle bond1Gd alloy sheet with weak elliptical-texture was fabricated by cold rolling and subsequent annealing,and it showed an excellent Erichsen(IE)value near 7.1 mm.Both quasi-in-situ electron backscatter diffraction(EBSD)and transmission electron microscopy(TEM)analysis indicate that considerable basal and pyramidal dislocations can be activated in the cold rolling process.During annealing,these dislocations can induce nucleation and then cause preferential misorientation relationships around〈uvt0〉concerning the nuclei and parent grains,which can facilitate the formation of elliptical texture.Furthermore,the particle-stimulated nucleation(PSN)mechanism and the co-segregation of Zn and Gd at grain boundaries(GB)further weak texture intensity.Finally,the mechanical properties of the Mgsingle bond2Znsingle bond3Lisingle bond1Gd alloy sheet are significantly improved.
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Project(23JCYBJC01870)supported by the Natural Science Foundation of Tianjin,ChinaProject(U22A20119)supported by the National Natural Science Foundation of China。
文摘As a cathode material for thermal batteries,NiS_(2)has a high theoretical capacity but low thermal stability.Besides,the poor formability of NiS_(2)powders also restricts the cathode performance of thermal batteries.In this paper,the novel NiS_(2)/SiO_(2)composite material was developed by high temperature vulcanization to improve the thermal stability formability of NiS_(2).The good filling and lubrication of spherical SiO_(2)can improve the thermal conductivity of NiS_(2)electrode.The discharge test shows that the NiS_(2)/SiO_(2)cathode has a stable discharge voltage at a current density of 200 mA/cm^(2),and the activation time is shortened by nearly 20%compared with the NiS_(2)cathode.In addition,due to the favorable thermal insulation protection of SiO_(2),the initial decomposition temperature of NiS_(2)is increased by 30℃after the addition of SiO_(2).The incorporation of SiO_(2)not only effectively improves the thermal stability and electrochemical properties of NiS_(2),but also improves the cold pressing forming performance of the NiS_(2)powder.Therefore,the novel NiS_(2)/SiO_(2)composite material is more suitable for thermal batteries with high stability and fast response,which is of great significance for improving the maneuverability and quality reliability of weapons and equipment.
基金supported by the Science and Engineering Research Board(SERB),a statutory body of the Department of Science&Technology(DST),Government of India through the Start-up Research Grant(SRG)scheme(File No.SRG/2020/000341).
文摘In this study,the effects of pre-strain-induced tensile twins(TTWs)and controlled heat treatment on the formability behavior of AZX311 Mg alloy sheets were investigated.A 4%compressive strain was applied to pre-strain the sheets using the in-plane compression(IPC)technique along the rolling direction(RD)to introduce TTWs.The pre-strained(PS)samples were subsequently heat-treated at 250℃,350℃,and 400℃ independently for 1 hr,and are termed as PSA1,PSA2,and PSA3,respectively.Erichsen cupping tests were conducted to assess the formability of the sheet samples under different initial conditions.The results showed that the PS sample heat-treated at 250℃ for 1hr exhibited a decrease in the Erichsen index(IE)compared to the as-rolled sample,whereas PSA2 and PSA3 samples showed an increase in IE values.Microtexture analysis revealed that most of the TTWs generated through pre-twinning were stable at 250℃;however,the twin volume fraction reduced to 41%at 350℃ compared to the PS samples due to enhanced thermal activity at that temperature.Furthermore,PSA2 samples showed severe grain coarsening in some areas of the sample,and the fraction of such grains increased in the PSA3 samples.The stretch formability(IE value)of PSA2 samples showed a 32.3%increase compared to the as-rolled specimens.Additionally,the analysis of the deformed specimen at failure under the Erichsen test indicated that considerable detwinning occurs in the PS and PSA1 samples,whereas dislocation slip activity dominates in the PSA2 and PSA3 samples during stretch forming.Apart from detwinning and dislocation slip,deformation twins were also observed in all samples after the Erichsen test.Thus,this work highlights the importance of texture control and its underlying mechanisms via pre-twinning followed by heat treatment and their impact on the room temperature(RT)stretch formability of AZX311 Mg alloy sheets.
基金Project(51205260)supported by the National Natural Science Foundation of ChinaProject(L2012046)supported by the Liaoning Provincial Committee of Education,China
文摘The influences of strength coefficient K, work hardening exponent n and thickness t of the overlapping sheet on bulging process are analyzed based on hardening material model. Also, bulging experiments are carried out by taking the aluminum alloy LF21 as formed sheet metal, and selecting overlapping sheet with different thicknesses and material properties, by which accuracy of the above analysis result is verified in the aspects of geometric shape, thickness distribution and limit bulging height. The results show that higher strength coefficient K, larger work hardening exponent n and proper thickness of the overlapping sheet are helpful to improve the formability and forming uniformity of formed sheet metal.
基金Project(CSTC2010AA4035)supported by Scientific and Technological Project of Chongqing Science and Technology Commission,ChinaProject(50504019)supported by the National Natural Science Foundation of China+1 种基金Project(CDJZR11130008)supported by the Fundamental Research Funds for the Central Universities,ChinaProject(CDJXS10130001)supported by the Chongqing University Postgraduates'Science and Innovation Fund,China
文摘The effect of the repeated unidirectional bending （RUB） process and annealing on the formability of magnesium alloy sheets was investigated. The RUB process and annealing treatments produce two effects on microstructure： grain coarsening and weakening of the texture. The sheet that underwent RUB and was annealed at 300 ℃exhibits the best formability owing to the reduction of the （0002） basal texture intensity, which results in low yield strength, large fracture elongation, small Lankford value （r-value） and large strain hardening exponent （n-value）. Compared with the as-received sheet, the coarse-grain sheet produced by RUB and annealing at 400 ℃ exhibits lower tensile properties but higher formability. The phenomenon is because the deformation twin enhanced by grain coarsening can accommodate the strain of thickness.
基金Project(CSTC2010AA4035) supported by Scientific and Technological Project of Chongqing Science and Technology Commission, ChinaProject(CDJZR11130008) supported by the Fundamental Research Funds for the Central Universities,ChinaProject (2008DFR50040) supported by the Ministry of Science and Technology of China
文摘The effects of strain rate on microstructure and formability of AZ31B magnesium alloy sheets were investigated through uniaxial tensile tests and hemispherical punch tests with strain rates of 10^-4, 10^-3, 10^-2, 10^-1 s^-1 at 200℃. The results show that the volume fraction of dynamic recrystallization grains increases and the original grains are gradually replaced by recrystallization grains with the strain rate decreasing. A larger elongation and a smaller r-value are obtained at a lower strain rate, moreover the erichsen values become larger with the strain rate reducing, so the formability improves. This problem arises in part from the enhanced softening and the coordination of recrystallization grains during deformation.
基金Project (51275185) supported by the National Natural Science Foundation of China
文摘Flow behavior of the Al-Si coated boron steel was investigated with Gleeble-3500,in comparison with the uncoated one.Effect of deformation conditions on the coating integrity was characterized by optical microscopy.Facture surfaces of the coated steels were inspected under SEM.Experimental results indicate that the ultimate tensile strength and ductility of the Al-Si coated boron steel are lower than those of the uncoated steel under test conditions.Extensive cracks occur in the coating after tensile tests;the width and density of cracks are sensitive to the deformation temperatures and strain rates.The bare substrate exposed between the separate coating segments is oxidized.Appearance of the oxide degrades the Al-Si coating adhesion.Remarkable difference between formability of the coating layer and the substrate is confirmed.The formability of the Al-Si coating could be optimized by controlling the phase transformation of the ductile Fe-rich intermetallic compounds within it during the austenization.
基金Project(50805033)supported by the National Natural Science Foundation of ChinaProject(E200804)supported by the Natural Science Foundation of Heilongjiang Province of China
文摘Ring hoop tension test and tube bulging test were carried out at elevated temperatures up to 480 ℃to evaluate the formability of AZ31B extruded tube for internal high pressure forming （IHPF） process. The total elongation along hoop direction and the maximum expansion ratio （MER） of the tube were obtained. The fracture surface after bursting was also analyzed. The results show that the total elongation along hoop direction and the MER value have a similar changing tendency as the testing temperature increases, which is quite different from the total elongation along axial direction. Both the total elongation along hoop direction and the MER value increase to a peak value at about 160 ℃. After that, they begin to decrease quickly until a certain rebounding temperature is reached. From the rebounding temperature, they begin to increase rapidly again. Burnt structure appears on the fracture surface when tested at temperatures higher than 420 ℃. Therefore, the forming temperature of the tested tube should be lower than 420 ℃, even though bigger formability can be achieved at higher temperature.
基金Project(HIT.NSRIF.2009033) supported by the Scientific Research Foundation of Harbin Institute of Technology,China
文摘The formability of AA5052/polyethylene/AA5052 sandwich sheets was experimentally studied. Three kinds of AA5052/polyethylene/AA5052 sandwich specimens with different thicknesses of core materials were prepared by the hot pressing adhesive method. Then, the uniaxial tensile tests were conducted to investigate the mechanical properties of AA5052/polyethylene/ AA5052 sandwich sheets, and the stretching tests were carried out to investigate the influences of polymer core thickness on the limit dome height of the sandwich sheet. The forming limit curves for three kinds of sandwich sheets were obtained. The experimental results show that the forming limit of the AA5052/polyethylene/AA5052 sandwich sheet is higher than that of the monolithic AA5052 sheet, and it increases with increasing the thickness of polyethylene core.
文摘Experimental study has been conducted for an interstitial free(IF) sheet steel on its surface roughness evolution and formability with respect to grain size and sheet thickness effect. The surface roughness of IF sheet steel is proportional to effective strain, grain size and inversely proportional to sheet thickness; the larger grain reduces the formability by accelerating the surface roughening rate and enhance formability by raising the workhardening rate, while the latter effect plays the dominate role. The grain size effect on surface roughening and formability is more obvious when the sheets are thinner.
基金the National Natural Science Foundation of China (No. 50905144)the Program for New Century Excellent Talents in University, the Natural Science Basic Research Plan in Shaanxi Province (No. 2011JQ6004)the 111 Project (No. B08040) for the support given to this research
文摘Aluminum alloy （Al-alloy） thin-walled （D/t ＆gt; 20, diameter D, wall thickness t） bent tubes have attracted increasing applications in many industries with mass quantities and diverse specifications due to satisfying high strength to weigh ratio requirements of product manufacturing. However, due to nonlinear nature of bending with coupling effects of multiple factors, the similarity theory seems not applicable and there occurs a challenge for efficient and reliable evaluation of the bending formability of thin-walled tube with various bending specifications. Considering the unequal deformation and three major instabilities, the bending formability of thin-walled Al-alloy tube in changing tube sizes such as D and t are clarified via both the analytical and FE modeling/ simulations. The experiments of rotary draw bending are conducted to validate the theoretical models and further confirm ＇size effect＇ related bending formability. The major results show that （1） The anti-wrinkling capability of tube decreases with the larger D and smaller t, and the effect significance of t is larger than that of D even under rigid supports; （2） The wall thinning increases with the larger D and smaller t, and this tendency becomes much more obvious under rigid supports; （3） The cross-section deformation increases with the larger D and smaller t according to the analytical model obtained intrinsic relationship, while this tendency becomes opposite due to the nonlinear role of mandrel die; （4） The size factor D/t can be used as a nondimensional index to evaluate both the bending formability regarding the wall thinning and cross-section deformation.
