Numerical analysis of keyhole shape and keyhole establishment time is of great significance for selection and optimization of the process parameters in keyhole plasma arc welding. In this paper, a three-dimensional tr...Numerical analysis of keyhole shape and keyhole establishment time is of great significance for selection and optimization of the process parameters in keyhole plasma arc welding. In this paper, a three-dimensional transient model is developed to analyze the evolutions of keyhole shape and keyhole establishment time in continuous current plasma arc welding process. Firstly, a combined volumetric heat source model is used to simulate the transient variation of temperature field. And then the surface deformation equation is adopted to calculate dynamic features of the keyhole shape and keyhole establishment time inside weld pool, in which the force action on weld pool surface is considered. Experiment is cond^ted to validate the numerical simulation results. The predicted keyhole size and keyhole establishment time are in agreement with the experimental measurement. And the calculated fusion zone geometry is consistent with the measured one.展开更多
To study the influence of texture on Hall-Petch slope,the Hall-Petch relationships of two hot-extruded AZ31 alloys(A117 and A189)were determined by the measurement of yield strength at room temperature.To determine th...To study the influence of texture on Hall-Petch slope,the Hall-Petch relationships of two hot-extruded AZ31 alloys(A117 and A189)were determined by the measurement of yield strength at room temperature.To determine the real texture difference,the texture changes were facilitated by the variation of extrusion ratio and demonstrated by the actual grain orientation distributions.The A117 alloys exhibited higher Hall-Petch slope in comparison of A187 in the condition of tension and compression,because A117 alloys had lower volume fraction of grains in the range of basal pole 75°-90°.The Hall-Petch slope differences for both alloys were analyzed and discussed by boundary obstacle against deformation propagation in grains with various orientation.Due to the higher volume fraction of grains in the range of basal pole 75°-90°in A189,the effect of hindering dislocation slip or twinning propagation by grains boundary was weaker than of A117.展开更多
The microstructure and tensile properties of Sn-9Zn solder under different cooling and aging condition were studied. During solidification,the distribution of Zn-rich phases and grain size in the microstructure of Sn-...The microstructure and tensile properties of Sn-9Zn solder under different cooling and aging condition were studied. During solidification,the distribution of Zn-rich phases and grain size in the microstructure of Sn-9Zn solder were decided by the cooling rate. The Zn-rich phase in Sn-9Zn solder under furnace cooling,air cooling and water cooling media was separately existed as coarsen dendritic and needle like shape,fine needle like shape and very fine rod-like shape,respectively. After aging,the coarsen dendritic was broken and the coarsen needle like Zn-rich phase was partly changed into fine distribution of Zn-rich phase for Sn-9Zn solder with furnace cooling,and the rod-like Zn phase in the Sn-9Zn solder under water cooling was changed to conglomerated Zn with needle shape. During tensile testing on Sn-9Zn solder,tensile strength and ductility reached the best with water cooling,but decreased with aging effect. Meanwhile,the ductility of solder with air cooling and the strength of solder with furnace cooling increased with aging. The fracture mode was ductile and was independent of cooling media and aging effect. The size and depth of dimples decreased from water,furnace to air cooling.After aging,number and size of dimples increased on the solder with furnace cooling and air cooling. The change on the size of dimples for the Sn-9Zn solder under different cooling condition and with aging effect was accordance to the tensile properties.展开更多
Twin roll cast ZK60 alloy strip/sheet with final thickness of 0.5 mm was prepared,and effect of rolling temperature on microstructure and texture development was investigated using OM and XRD technique,microstructure ...Twin roll cast ZK60 alloy strip/sheet with final thickness of 0.5 mm was prepared,and effect of rolling temperature on microstructure and texture development was investigated using OM and XRD technique,microstructure and texture were measured on specimens subjected to rolling experiment at different rolling temperature,and macrotexture was also evaluated by X-ray diffraction method.In addition,the(1 010)and(0002) pole figures were measured,and the tensile test was performed to reveal the influence of rolling temperature on mechanical properties.The results show that the microstructure of ZK60 alloy sheet consisted of fibrous structure with elongated grains,and shear bands along the rolling direction after warm rolling.Dynamic recrystallization could be found during the warm rolling process at rolling temperature 350 °C and above.And many fine recrystallized grain could be observed in the shear bands area.It is a little difficult to see the recrystallized grain in the sheet warm rolled at 300 °C because of higher density of shear bands.The warm rolled ZK60 alloy sheet exhibited strong(0002) pole texture,the intensity of(0002) pole figure decreases with the increasing of rolling temperature and the basal pole tilted slightly to the transverse direction after warm rolling.展开更多
AZ31 alloy sheet fabricated by rolling was processed by friction stir processing(FSP) with different passes. The effect of FSP on the microstructure and damping capacity of AZ31 alloy sheet was discussed. The fine and...AZ31 alloy sheet fabricated by rolling was processed by friction stir processing(FSP) with different passes. The effect of FSP on the microstructure and damping capacity of AZ31 alloy sheet was discussed. The fine and equiaxed grains were obtained in the stirred zone(SZ) for FSPed samples from 1 pass to 3 passes with the average grain size of 10.6, 10.4 and 13.6 μm, respectively. The damping peak P_1 was presented on the curves of temperature-dependent damping capacity for FSPed samples. The damping peak P_2 was restrained after FSP and the damping peak P_1 was a relaxation process. The FSPed samples(2-pass FSP and 3-pass FSP) obtained high damping capacity. The best damping valuesQ_0^(-1)(ε=10_(-4)) and damping values Q_H^(-1)(ε=10^(-3)) of the sample subjected to 3-pass FSP(0.0131 and 0.0496) increased by 33.7% and 157.0%, respectively.展开更多
Partial transient liquid-phase bonding (PTLP bonding) of Si3N4 ceramic with Ti/Cu/Ti multi-interlayer is performed with changing the thickness of Ti foil. The influence of Ti foil thickness on interface structure an...Partial transient liquid-phase bonding (PTLP bonding) of Si3N4 ceramic with Ti/Cu/Ti multi-interlayer is performed with changing the thickness of Ti foil. The influence of Ti foil thickness on interface structure and joint strength was discussed. The joint interface structures are investigated by scanning electron microscope (SEM) and energy dispersion spectroscopy(EDS). The results show that the maximum joint strength of 210 MPa is obtained at room temperature in the experiments. When joining temperature and time are not changed and the process of isothermal solidification is sufficient , interface structure, reaction layer thickness and isothermal solidification thickness change with the thickness of Ti foil.展开更多
The three dimensiotud transient weld pool dynamics are numerically analyzed ,for Forcearc welding, which is a new gas metal arc welding technology to get deep fusion penetration with smaller angle sf V groove to enhan...The three dimensiotud transient weld pool dynamics are numerically analyzed ,for Forcearc welding, which is a new gas metal arc welding technology to get deep fusion penetration with smaller angle sf V groove to enhance welding efficiency significantly. The influence of groove angle and preheatin,g temperature on heat and .fluid .flow is studied and compared to get an optimal welding parameter. Good agreement is shown between the predicted and experimental results, such as weld bead cross-section and thermal cycles. It can he seen that an apprpriate groove angle could be used to replace high preheating temperature to get inproced penetration and thermal cycles.展开更多
An intelligent fuzzy c-means system for process monitoring and recognition of process disturbances during short- circuiting gas metal arc welding (GMAW) is introduced in this paper. The raw measured and statisticall...An intelligent fuzzy c-means system for process monitoring and recognition of process disturbances during short- circuiting gas metal arc welding (GMAW) is introduced in this paper. The raw measured and statistically test data of probability density distribution ( PDD ) and class frequency distribution ( CFD ) of welding electrical parameters are further processed into a 7-dimensional array which is designed to describe various welding conditions, and is employed as input vector of the intelligent fuzzy c-means system. The fuzzy c-means system is used to conduct process monitoring and automatic recognition. The correct recognition rate of 24 test data under 8 kinds of welding condition is 92%.展开更多
A new type of semi-IPN gel electrolyte was prepared by thermal polymerization in this article.The cross-linked PEG200 (MXPEG) was prepared by condensation reaction in the presence of methacryloxypropyltrimethoxysilane...A new type of semi-IPN gel electrolyte was prepared by thermal polymerization in this article.The cross-linked PEG200 (MXPEG) was prepared by condensation reaction in the presence of methacryloxypropyltrimethoxysilane (MAPTMS),the condensation product was then blent with PMMA and polymerized to form polymer blends with semi-IPN fabric.Differential scanning calorimetry and X-ray diffraction spectroscopy were used to investigate the thermal transition behavior of the polymer blends prepared.Ion-conducting behaviors and the electrochemical stability window for semi-IPN gel electrolyte were investigated by means ofimpedance spectroscopy and linear sweep voltammetry.The Arrhenius-type relationship was observed in the temperature dependence ofionic conductivity.All the properties shows that the prepared semi-IPN gel electrolyte possesses certain levels of electrolye salt and plasticizer were expected to have applications of gel polymer electrolyte for lithium polymer secondary batteries.展开更多
The improvement of mechanical properties of ZK60 processed by asymmetric reduction rolling (ARR) was investigated in this paper. The grain refinement and basal texture intensity decrease were attributed to the intro...The improvement of mechanical properties of ZK60 processed by asymmetric reduction rolling (ARR) was investigated in this paper. The grain refinement and basal texture intensity decrease were attributed to the introduction of shear stress produced by ARR process. Compared to conventional symmetrical rolled (SR) ZK60 alloys, ARRed ZK60 exhibited finer, more homogeneous grains and higher mechanical properties. The intensity of basal texture of ARRed ZK60 after annealing was lower than that of SRed ZK60 after annealing. ZK60 sheet with good combination of strength and ductility could be obtained by ARR process. The yield strength (YS) and ultimate tensile strength (UTS) of the ARRed ZK60 sheet were increased 150% and 91.3%, compared to those of SRed ZK60 sheet, from 80 to 200 MPa and from 140 to 264 MPa, respectively. Simultaneously, the elongation to failure increased by 68.75% in the ARR sheet (27%) when compared to that of the SR sheet (16%).展开更多
The influence of asymmetric reduction rolling (ARR) on the microstructure, texture and mechanical properties of AZ91 was investigated. The microstructural characteristics of the AZ91 sheet processed by symmetric ro...The influence of asymmetric reduction rolling (ARR) on the microstructure, texture and mechanical properties of AZ91 was investigated. The microstructural characteristics of the AZ91 sheet processed by symmetric roiling (SR) were the twins, intersection of twins and dynamic recrystalization (DRX) grains around the coarse grains and within the twins. However, the amount of twins and DRX grains in ARRed AZ91 was much smaller than that in SRed AZ91. The SRed AZ91 after annealing exhibited fine DRX grains and some coarse grains with a size of ~ 100 pro. The grains in ARRed AZ91 after annealing were much finer and more homogeneous than those in SRed AZ91 after annealing. The intensity of basal texture of ARRed AZ91 after annealing was lower than that of SRed AZ91 rolling after annealing. The average Schmid factor of ARRed AZ91 is 0.34, which is higher than that of SRed AZ91. The yield strength and ultimate tensile strength of the ARRed AZ91 sheet were inCreased to 16.1% and 31.8% compared to SRed AZ91 sheet, from 155 to 180 MPa, and from 220 to 290 MPa, respectively. The improvement of mechanical properties in ARRed AZ91 after annealing was attributed to much finer, more homogeneous DRX grains and weaker basal texture.展开更多
文摘Numerical analysis of keyhole shape and keyhole establishment time is of great significance for selection and optimization of the process parameters in keyhole plasma arc welding. In this paper, a three-dimensional transient model is developed to analyze the evolutions of keyhole shape and keyhole establishment time in continuous current plasma arc welding process. Firstly, a combined volumetric heat source model is used to simulate the transient variation of temperature field. And then the surface deformation equation is adopted to calculate dynamic features of the keyhole shape and keyhole establishment time inside weld pool, in which the force action on weld pool surface is considered. Experiment is cond^ted to validate the numerical simulation results. The predicted keyhole size and keyhole establishment time are in agreement with the experimental measurement. And the calculated fusion zone geometry is consistent with the measured one.
基金Funded by the National Natural Science Foundation of China(No.51271046)the Liaoning Science and Technology Joint Fund(Nos.2020-YKLH-26 and 2021-YKLH-19)+3 种基金the Liaoning Science and Technology Projects(No.20180550724)the Foundation of Liaoning Key Laboratory of Chemical Additive Synthesis and Separation(No.ZJNK2109)the Doctoral Business and Innovation Launching Plan of Ying Kou City(No.QB-2019-10)the HighLevel Talent Research Startup Foundation of Yingkou Institute of Technology(Nos.YJRC202008 and YJRC202009)。
文摘To study the influence of texture on Hall-Petch slope,the Hall-Petch relationships of two hot-extruded AZ31 alloys(A117 and A189)were determined by the measurement of yield strength at room temperature.To determine the real texture difference,the texture changes were facilitated by the variation of extrusion ratio and demonstrated by the actual grain orientation distributions.The A117 alloys exhibited higher Hall-Petch slope in comparison of A187 in the condition of tension and compression,because A117 alloys had lower volume fraction of grains in the range of basal pole 75°-90°.The Hall-Petch slope differences for both alloys were analyzed and discussed by boundary obstacle against deformation propagation in grains with various orientation.Due to the higher volume fraction of grains in the range of basal pole 75°-90°in A189,the effect of hindering dislocation slip or twinning propagation by grains boundary was weaker than of A117.
基金Project(BK2003045) supported by the Natural Science Foundation of Jiangsu Province, China Project(03KJB430006) supported by the Natural Science Foundation of High School of Jiangsu Province
基金supported by the Natural Science Foundation of Jiangsu Province(Grant No.BK2012163)University Science Research Project of Jiangsu Province(Grant No.11KJB460003)
文摘The microstructure and tensile properties of Sn-9Zn solder under different cooling and aging condition were studied. During solidification,the distribution of Zn-rich phases and grain size in the microstructure of Sn-9Zn solder were decided by the cooling rate. The Zn-rich phase in Sn-9Zn solder under furnace cooling,air cooling and water cooling media was separately existed as coarsen dendritic and needle like shape,fine needle like shape and very fine rod-like shape,respectively. After aging,the coarsen dendritic was broken and the coarsen needle like Zn-rich phase was partly changed into fine distribution of Zn-rich phase for Sn-9Zn solder with furnace cooling,and the rod-like Zn phase in the Sn-9Zn solder under water cooling was changed to conglomerated Zn with needle shape. During tensile testing on Sn-9Zn solder,tensile strength and ductility reached the best with water cooling,but decreased with aging effect. Meanwhile,the ductility of solder with air cooling and the strength of solder with furnace cooling increased with aging. The fracture mode was ductile and was independent of cooling media and aging effect. The size and depth of dimples decreased from water,furnace to air cooling.After aging,number and size of dimples increased on the solder with furnace cooling and air cooling. The change on the size of dimples for the Sn-9Zn solder under different cooling condition and with aging effect was accordance to the tensile properties.
基金Project(35060905) supported by the Doctoral Foundation of Jiangsu University of Science and Technology
文摘Twin roll cast ZK60 alloy strip/sheet with final thickness of 0.5 mm was prepared,and effect of rolling temperature on microstructure and texture development was investigated using OM and XRD technique,microstructure and texture were measured on specimens subjected to rolling experiment at different rolling temperature,and macrotexture was also evaluated by X-ray diffraction method.In addition,the(1 010)and(0002) pole figures were measured,and the tensile test was performed to reveal the influence of rolling temperature on mechanical properties.The results show that the microstructure of ZK60 alloy sheet consisted of fibrous structure with elongated grains,and shear bands along the rolling direction after warm rolling.Dynamic recrystallization could be found during the warm rolling process at rolling temperature 350 °C and above.And many fine recrystallized grain could be observed in the shear bands area.It is a little difficult to see the recrystallized grain in the sheet warm rolled at 300 °C because of higher density of shear bands.The warm rolled ZK60 alloy sheet exhibited strong(0002) pole texture,the intensity of(0002) pole figure decreases with the increasing of rolling temperature and the basal pole tilted slightly to the transverse direction after warm rolling.
基金Project(51301077)supported by the National Natural Science Foundation,ChinaProject(BK20130470)supported by the Natural Science Foundation of Jiangsu Province,ChinaProject supported by Priority Academic Program Development of Jiangsu Higher Education Institutions,China
文摘AZ31 alloy sheet fabricated by rolling was processed by friction stir processing(FSP) with different passes. The effect of FSP on the microstructure and damping capacity of AZ31 alloy sheet was discussed. The fine and equiaxed grains were obtained in the stirred zone(SZ) for FSPed samples from 1 pass to 3 passes with the average grain size of 10.6, 10.4 and 13.6 μm, respectively. The damping peak P_1 was presented on the curves of temperature-dependent damping capacity for FSPed samples. The damping peak P_2 was restrained after FSP and the damping peak P_1 was a relaxation process. The FSPed samples(2-pass FSP and 3-pass FSP) obtained high damping capacity. The best damping valuesQ_0^(-1)(ε=10_(-4)) and damping values Q_H^(-1)(ε=10^(-3)) of the sample subjected to 3-pass FSP(0.0131 and 0.0496) increased by 33.7% and 157.0%, respectively.
文摘Partial transient liquid-phase bonding (PTLP bonding) of Si3N4 ceramic with Ti/Cu/Ti multi-interlayer is performed with changing the thickness of Ti foil. The influence of Ti foil thickness on interface structure and joint strength was discussed. The joint interface structures are investigated by scanning electron microscope (SEM) and energy dispersion spectroscopy(EDS). The results show that the maximum joint strength of 210 MPa is obtained at room temperature in the experiments. When joining temperature and time are not changed and the process of isothermal solidification is sufficient , interface structure, reaction layer thickness and isothermal solidification thickness change with the thickness of Ti foil.
文摘The three dimensiotud transient weld pool dynamics are numerically analyzed ,for Forcearc welding, which is a new gas metal arc welding technology to get deep fusion penetration with smaller angle sf V groove to enhance welding efficiency significantly. The influence of groove angle and preheatin,g temperature on heat and .fluid .flow is studied and compared to get an optimal welding parameter. Good agreement is shown between the predicted and experimental results, such as weld bead cross-section and thermal cycles. It can he seen that an apprpriate groove angle could be used to replace high preheating temperature to get inproced penetration and thermal cycles.
基金The authors are grateful to the financial support provided by the National Natural Science Foundation of China under grant No. 51005106, Research Fund for the Doctoral Program of Jiangsu Uni- versity of Science and Technology under grant No. 35060902, A Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions.
文摘An intelligent fuzzy c-means system for process monitoring and recognition of process disturbances during short- circuiting gas metal arc welding (GMAW) is introduced in this paper. The raw measured and statistically test data of probability density distribution ( PDD ) and class frequency distribution ( CFD ) of welding electrical parameters are further processed into a 7-dimensional array which is designed to describe various welding conditions, and is employed as input vector of the intelligent fuzzy c-means system. The fuzzy c-means system is used to conduct process monitoring and automatic recognition. The correct recognition rate of 24 test data under 8 kinds of welding condition is 92%.
文摘A new type of semi-IPN gel electrolyte was prepared by thermal polymerization in this article.The cross-linked PEG200 (MXPEG) was prepared by condensation reaction in the presence of methacryloxypropyltrimethoxysilane (MAPTMS),the condensation product was then blent with PMMA and polymerized to form polymer blends with semi-IPN fabric.Differential scanning calorimetry and X-ray diffraction spectroscopy were used to investigate the thermal transition behavior of the polymer blends prepared.Ion-conducting behaviors and the electrochemical stability window for semi-IPN gel electrolyte were investigated by means ofimpedance spectroscopy and linear sweep voltammetry.The Arrhenius-type relationship was observed in the temperature dependence ofionic conductivity.All the properties shows that the prepared semi-IPN gel electrolyte possesses certain levels of electrolye salt and plasticizer were expected to have applications of gel polymer electrolyte for lithium polymer secondary batteries.
基金financially supported by the National Natural Science Foundation of China (No. 51271046)
文摘The improvement of mechanical properties of ZK60 processed by asymmetric reduction rolling (ARR) was investigated in this paper. The grain refinement and basal texture intensity decrease were attributed to the introduction of shear stress produced by ARR process. Compared to conventional symmetrical rolled (SR) ZK60 alloys, ARRed ZK60 exhibited finer, more homogeneous grains and higher mechanical properties. The intensity of basal texture of ARRed ZK60 after annealing was lower than that of SRed ZK60 after annealing. ZK60 sheet with good combination of strength and ductility could be obtained by ARR process. The yield strength (YS) and ultimate tensile strength (UTS) of the ARRed ZK60 sheet were increased 150% and 91.3%, compared to those of SRed ZK60 sheet, from 80 to 200 MPa and from 140 to 264 MPa, respectively. Simultaneously, the elongation to failure increased by 68.75% in the ARR sheet (27%) when compared to that of the SR sheet (16%).
基金financially supported by the National Natural Science Foundation of China(No.51271046)
文摘The influence of asymmetric reduction rolling (ARR) on the microstructure, texture and mechanical properties of AZ91 was investigated. The microstructural characteristics of the AZ91 sheet processed by symmetric roiling (SR) were the twins, intersection of twins and dynamic recrystalization (DRX) grains around the coarse grains and within the twins. However, the amount of twins and DRX grains in ARRed AZ91 was much smaller than that in SRed AZ91. The SRed AZ91 after annealing exhibited fine DRX grains and some coarse grains with a size of ~ 100 pro. The grains in ARRed AZ91 after annealing were much finer and more homogeneous than those in SRed AZ91 after annealing. The intensity of basal texture of ARRed AZ91 after annealing was lower than that of SRed AZ91 rolling after annealing. The average Schmid factor of ARRed AZ91 is 0.34, which is higher than that of SRed AZ91. The yield strength and ultimate tensile strength of the ARRed AZ91 sheet were inCreased to 16.1% and 31.8% compared to SRed AZ91 sheet, from 155 to 180 MPa, and from 220 to 290 MPa, respectively. The improvement of mechanical properties in ARRed AZ91 after annealing was attributed to much finer, more homogeneous DRX grains and weaker basal texture.