The research on numerical simulation for combinative process of SPF/DB is carried out in this paper. The contacting problem of sheets is analyzed by using the penalty method. In order to solve the contact problem of d...The research on numerical simulation for combinative process of SPF/DB is carried out in this paper. The contacting problem of sheets is analyzed by using the penalty method. In order to solve the contact problem of different parts of the sheet, a new algorithm for contacting judgment is proposed. According to the relation of the distance vector and the vector of contacting element area, and the condition of contact, it can be judged whether or not a node on the slave surface and the corresponding master surface are in the state of SPF/DB. The Mindlin shell element is employed to simulate SPF/DB process of an asymmetry double-cell cup of Ti-6Al-4V to examine the efficiency of the new algorithm using ARVIP-3D. The results of the numerical simulation are in good agreement with experimental results.展开更多
Superplastic forming and diffusion bonding (SPF/DB) is a well-established process for the manufacture of components almost exclusively from Ti-6AI-4V sheet material. The sandwich structure of Ti-6AI-4V alloy is invest...Superplastic forming and diffusion bonding (SPF/DB) is a well-established process for the manufacture of components almost exclusively from Ti-6AI-4V sheet material. The sandwich structure of Ti-6AI-4V alloy is investigated. The effects of the microstructure on the SPF/DB process were discussed. The microstructure at the interfaces and the distribution of thickness were researched.展开更多
The probability, main effect factors and diffusion theory of structural superplastic diffusion bonding of W6Mo5Cr4V2/45 steel have been observed and analyzed by means of tensile test at the room temperature, scanning ...The probability, main effect factors and diffusion theory of structural superplastic diffusion bonding of W6Mo5Cr4V2/45 steel have been observed and analyzed by means of tensile test at the room temperature, scanning electron microscope and microhardness test. Results show that after fine graining treatment and short time superplastic pressing formation under the conditions of superplastic temperature and strain rate, W6Mo5Cr4V2/45 specimens can achieve solid state diffusion bonding and the property of welded area is the same as the other parts in the specimen. The diffusion path of carbon element is intergranular and of dislocation.展开更多
The superplasticity of Ti_3Al intermetallic compounds has been investigated in this paper.The Ti-14Al-21Nb ternary alloy showed 477% elongation at the strain rate of 1.49×10^(-5) s^(-1) and 950℃.The elongation o...The superplasticity of Ti_3Al intermetallic compounds has been investigated in this paper.The Ti-14Al-21Nb ternary alloy showed 477% elongation at the strain rate of 1.49×10^(-5) s^(-1) and 950℃.The elongation of Ti-14Al-21 Nb-3Mo-1V quinary alloy approached to 573% at the strain rate of 4.52×10^(-5) s^(-1) and the same temperature,and it was found that the elongation value in- creased to 1096.4%as temperature was raised up to 980℃ at the same strain rate.Ti_3Al base al- loys were bonded by diffusion bonding technology and good joints were created,the simulated specimens were performed by SPF/DB process.展开更多
The superplasticity and diffusion bonding of IN718 superalloy were studied in this article. The strain rate sensitivity index m was obtained at different temperatures and various initial strain rates using the tensile...The superplasticity and diffusion bonding of IN718 superalloy were studied in this article. The strain rate sensitivity index m was obtained at different temperatures and various initial strain rates using the tensile speed mutation method; m reached its maximum value 0.53 at an initial strain rate of 1×10^-4s^-1 at 1253K. The diffusion bonding parameters, including the bonding temperature T, pressure p, and time t, affected the mechanism of joints. When the bonded specimen with 25μm thick nickel foil interlayer was tensile at room temperature, the shear fracture of the joints with nickel foil interlayer took place at the IN718 part. Microstructure study was carried out with the bonded samples. The microstructure shows an excellent bonding at the interfaces. The optimum parameters for the diffusion bonding are： T = 1273-1323K, p = 20-30MPa, t = 45-60min.展开更多
The elevated temperature tensile experiments have been carried out on the magnesium alloy and results indicate that the magnesium alloy has excellent superplastic property. Gleebe 1500 testing machine was used in t...The elevated temperature tensile experiments have been carried out on the magnesium alloy and results indicate that the magnesium alloy has excellent superplastic property. Gleebe 1500 testing machine was used in the diffusion bonding experiment on the superplastic magnesium alloy. Then, the shear strength of the joints under different conditions is obtained through shear testing and the optimum processing parameters for the diffusion bonding are achieved. By metallurgical microscope and scanning electron microscope (SEM), it is revealed that the micromechanism of diffusion bonding is the slide of grain boundaries caused by the growth of grains and atom diffusion of the superplastic magnesium alloy.展开更多
The superplastic forming and application of GH4169 superalloy are studied. It is shown that for the typical superplastic forming strain rates of 10- 3 s 1 to 10- 4 s -1, the available engineering strains of the fine-g...The superplastic forming and application of GH4169 superalloy are studied. It is shown that for the typical superplastic forming strain rates of 10- 3 s 1 to 10- 4 s -1, the available engineering strains of the fine-grain GH4169 superalloy are always higher than 250% within wide temperature scopes (920 -980℃), and the maximum elongation to failure obtained is 513%. Dynamic grain growth is presented during superplastic deforming for the alloy, and the grain becomes larger with the increase of the strain. A GH4169 fuel manifold of an aerocraft is superplastically formed, and the superplastically formed GH4169 mainfold is tested by 30 MPa hydraulic pressure for 10 min. So some GH4169 alloy complex components can be superplastically formed in the aerospace industry to decrease the costs of fabricating these components.展开更多
The effect of main technological parameters of diffusion bonding for titanium alloy, such as temperature,pressure and time,on joint strength was studied. A threedimensional curved surface among'joint strength and ...The effect of main technological parameters of diffusion bonding for titanium alloy, such as temperature,pressure and time,on joint strength was studied. A threedimensional curved surface among'joint strength and temperature,pressure,time was drawn. It can be used for selecting reasonable technological parameters.In order to have an overall understanding of the effeCt of technological parameters on the quality of bonded interfaces,the observation of fracture appearance by SEM was also carried out.展开更多
Diffusion bonding of supcrplastic Al alloy LC4,with prior surface treatment of organic solution protecting coating after electroplishing and stainless steel wool brushing,was performed by Gleeble test machine under co...Diffusion bonding of supcrplastic Al alloy LC4,with prior surface treatment of organic solution protecting coating after electroplishing and stainless steel wool brushing,was performed by Gleeble test machine under conditions ranged 490—530 ℃,1.0—3.0 MPa. 30—180 min and vacuum of 1.0×10^(-3) Pa.The joints were examined to have similar strength and microstructure to the base metal Discussion was made on the effect of superplastic treatment on bonding.The micromechanism for diffusion bonding of super- plastic metal was suggested as the migration of original bond interfaces caused by atomic diffusion and grain growth. Experimental results for the alloy as quench-aged state were presented to compare with the superplastic one.展开更多
Superplastic forming is a practical method to manufacture complex-shaped parts of titanium alloys with large deformation.Laminated parts of dissimilar titanium alloys fabricated by superplastic forming can achieve exc...Superplastic forming is a practical method to manufacture complex-shaped parts of titanium alloys with large deformation.Laminated parts of dissimilar titanium alloys fabricated by superplastic forming can achieve excellent performance by combining the advantages of components.This work displays the superplastic tension behavior and microstructural evolution of dissimilar TC4/SP700 laminate prepared by the diffusion bonding process.Two titanium alloys can achieve metallurgical bonding at parameters of 800℃/1 h/5 MPa.Except for dynamic recrystallization and grain growth behaviors upon superplastic tension,stress-induced phase transformation plays an important role inαtoβphase transformation apart from the elevated temperature.The superplastic deformation can be attributed to the grain boundary sliding accommodated multiplex motion of dislocations.In addition,the retained strengths of all dissimilar TC4/SP700 laminates after superplastic deformation with different strain rates and temperatures range from 807 to 890 MPa.展开更多
The superplastic deformation diffusion bonding of 00Cr25Ni7Mo3N duplex stainless steel was performed on a hot simulator. The microstructure of the bonding interface was characterized by scanning electron microscopy （...The superplastic deformation diffusion bonding of 00Cr25Ni7Mo3N duplex stainless steel was performed on a hot simulator. The microstructure of the bonding interface was characterized by scanning electron microscopy （SEM） and electron backscatter diffraction （EBSD）. The mechanical properties of the specimen were investigated by a shear strength test. The results indicated that the shear strength was improved with the increase of superplastic deformation reduction. When the deformation reduction was up to 50%, the shear strength of the specimen achieved 417 Mpa, approaching to that of the base metal. In addtion, the superplastic diffusion bonding technique was not very sensitive to surface roughness levels. When the surface roughness of the bonding specimen surpassed 0.416 pan （level G2）, the shear strength achieved at least 381 MPa.展开更多
Based on current theories of diffusion and creep cavity closure at high temperature, a theoretical analysis of phase transformation diffusion bonding for T8/T8 eutectoid steel is carried out. The diffusion bonding is ...Based on current theories of diffusion and creep cavity closure at high temperature, a theoretical analysis of phase transformation diffusion bonding for T8/T8 eutectoid steel is carried out. The diffusion bonding is mainly described as two-stage process: Ⅰ The interfacial cavity with shape change from diamond to cylinder.Ⅱ The radius of the cylindrical cavity are reduced and eliminated gradually. A new theoretical model is established for the process of transformation superplastic diffusion bonding (TSDB) on the basis of a theoretical model for isothermal superplastic diffusion. The model can predict the bonding quality which is affected by technological parameters, such as limit cycling temperature, the compressive stress, the numbers of thermal cycles and temperature cycling through the phase transformation in the thermal cycling and so on. Results show that the maximum temperature, the compressive stress, the numbers of thermal cycles and the rate of temperature changing speed in the thermal cycling have an important influence on TSDB process. Meanwhile, reasonable technological parameters chosen from theoretical analysis is in good agreement with those obtained from experimental results.展开更多
文摘The research on numerical simulation for combinative process of SPF/DB is carried out in this paper. The contacting problem of sheets is analyzed by using the penalty method. In order to solve the contact problem of different parts of the sheet, a new algorithm for contacting judgment is proposed. According to the relation of the distance vector and the vector of contacting element area, and the condition of contact, it can be judged whether or not a node on the slave surface and the corresponding master surface are in the state of SPF/DB. The Mindlin shell element is employed to simulate SPF/DB process of an asymmetry double-cell cup of Ti-6Al-4V to examine the efficiency of the new algorithm using ARVIP-3D. The results of the numerical simulation are in good agreement with experimental results.
文摘Superplastic forming and diffusion bonding (SPF/DB) is a well-established process for the manufacture of components almost exclusively from Ti-6AI-4V sheet material. The sandwich structure of Ti-6AI-4V alloy is investigated. The effects of the microstructure on the SPF/DB process were discussed. The microstructure at the interfaces and the distribution of thickness were researched.
文摘The probability, main effect factors and diffusion theory of structural superplastic diffusion bonding of W6Mo5Cr4V2/45 steel have been observed and analyzed by means of tensile test at the room temperature, scanning electron microscope and microhardness test. Results show that after fine graining treatment and short time superplastic pressing formation under the conditions of superplastic temperature and strain rate, W6Mo5Cr4V2/45 specimens can achieve solid state diffusion bonding and the property of welded area is the same as the other parts in the specimen. The diffusion path of carbon element is intergranular and of dislocation.
文摘The superplasticity of Ti_3Al intermetallic compounds has been investigated in this paper.The Ti-14Al-21Nb ternary alloy showed 477% elongation at the strain rate of 1.49×10^(-5) s^(-1) and 950℃.The elongation of Ti-14Al-21 Nb-3Mo-1V quinary alloy approached to 573% at the strain rate of 4.52×10^(-5) s^(-1) and the same temperature,and it was found that the elongation value in- creased to 1096.4%as temperature was raised up to 980℃ at the same strain rate.Ti_3Al base al- loys were bonded by diffusion bonding technology and good joints were created,the simulated specimens were performed by SPF/DB process.
文摘The superplasticity and diffusion bonding of IN718 superalloy were studied in this article. The strain rate sensitivity index m was obtained at different temperatures and various initial strain rates using the tensile speed mutation method; m reached its maximum value 0.53 at an initial strain rate of 1×10^-4s^-1 at 1253K. The diffusion bonding parameters, including the bonding temperature T, pressure p, and time t, affected the mechanism of joints. When the bonded specimen with 25μm thick nickel foil interlayer was tensile at room temperature, the shear fracture of the joints with nickel foil interlayer took place at the IN718 part. Microstructure study was carried out with the bonded samples. The microstructure shows an excellent bonding at the interfaces. The optimum parameters for the diffusion bonding are： T = 1273-1323K, p = 20-30MPa, t = 45-60min.
文摘The elevated temperature tensile experiments have been carried out on the magnesium alloy and results indicate that the magnesium alloy has excellent superplastic property. Gleebe 1500 testing machine was used in the diffusion bonding experiment on the superplastic magnesium alloy. Then, the shear strength of the joints under different conditions is obtained through shear testing and the optimum processing parameters for the diffusion bonding are achieved. By metallurgical microscope and scanning electron microscope (SEM), it is revealed that the micromechanism of diffusion bonding is the slide of grain boundaries caused by the growth of grains and atom diffusion of the superplastic magnesium alloy.
文摘The superplastic forming and application of GH4169 superalloy are studied. It is shown that for the typical superplastic forming strain rates of 10- 3 s 1 to 10- 4 s -1, the available engineering strains of the fine-grain GH4169 superalloy are always higher than 250% within wide temperature scopes (920 -980℃), and the maximum elongation to failure obtained is 513%. Dynamic grain growth is presented during superplastic deforming for the alloy, and the grain becomes larger with the increase of the strain. A GH4169 fuel manifold of an aerocraft is superplastically formed, and the superplastically formed GH4169 mainfold is tested by 30 MPa hydraulic pressure for 10 min. So some GH4169 alloy complex components can be superplastically formed in the aerospace industry to decrease the costs of fabricating these components.
文摘The effect of main technological parameters of diffusion bonding for titanium alloy, such as temperature,pressure and time,on joint strength was studied. A threedimensional curved surface among'joint strength and temperature,pressure,time was drawn. It can be used for selecting reasonable technological parameters.In order to have an overall understanding of the effeCt of technological parameters on the quality of bonded interfaces,the observation of fracture appearance by SEM was also carried out.
文摘Diffusion bonding of supcrplastic Al alloy LC4,with prior surface treatment of organic solution protecting coating after electroplishing and stainless steel wool brushing,was performed by Gleeble test machine under conditions ranged 490—530 ℃,1.0—3.0 MPa. 30—180 min and vacuum of 1.0×10^(-3) Pa.The joints were examined to have similar strength and microstructure to the base metal Discussion was made on the effect of superplastic treatment on bonding.The micromechanism for diffusion bonding of super- plastic metal was suggested as the migration of original bond interfaces caused by atomic diffusion and grain growth. Experimental results for the alloy as quench-aged state were presented to compare with the superplastic one.
基金The authors gratefully appreciate financial support by the National Natural Science Foundation of China(No.51875350).
文摘Superplastic forming is a practical method to manufacture complex-shaped parts of titanium alloys with large deformation.Laminated parts of dissimilar titanium alloys fabricated by superplastic forming can achieve excellent performance by combining the advantages of components.This work displays the superplastic tension behavior and microstructural evolution of dissimilar TC4/SP700 laminate prepared by the diffusion bonding process.Two titanium alloys can achieve metallurgical bonding at parameters of 800℃/1 h/5 MPa.Except for dynamic recrystallization and grain growth behaviors upon superplastic tension,stress-induced phase transformation plays an important role inαtoβphase transformation apart from the elevated temperature.The superplastic deformation can be attributed to the grain boundary sliding accommodated multiplex motion of dislocations.In addition,the retained strengths of all dissimilar TC4/SP700 laminates after superplastic deformation with different strain rates and temperatures range from 807 to 890 MPa.
文摘The superplastic deformation diffusion bonding of 00Cr25Ni7Mo3N duplex stainless steel was performed on a hot simulator. The microstructure of the bonding interface was characterized by scanning electron microscopy （SEM） and electron backscatter diffraction （EBSD）. The mechanical properties of the specimen were investigated by a shear strength test. The results indicated that the shear strength was improved with the increase of superplastic deformation reduction. When the deformation reduction was up to 50%, the shear strength of the specimen achieved 417 Mpa, approaching to that of the base metal. In addtion, the superplastic diffusion bonding technique was not very sensitive to surface roughness levels. When the surface roughness of the bonding specimen surpassed 0.416 pan （level G2）, the shear strength achieved at least 381 MPa.
文摘Based on current theories of diffusion and creep cavity closure at high temperature, a theoretical analysis of phase transformation diffusion bonding for T8/T8 eutectoid steel is carried out. The diffusion bonding is mainly described as two-stage process: Ⅰ The interfacial cavity with shape change from diamond to cylinder.Ⅱ The radius of the cylindrical cavity are reduced and eliminated gradually. A new theoretical model is established for the process of transformation superplastic diffusion bonding (TSDB) on the basis of a theoretical model for isothermal superplastic diffusion. The model can predict the bonding quality which is affected by technological parameters, such as limit cycling temperature, the compressive stress, the numbers of thermal cycles and temperature cycling through the phase transformation in the thermal cycling and so on. Results show that the maximum temperature, the compressive stress, the numbers of thermal cycles and the rate of temperature changing speed in the thermal cycling have an important influence on TSDB process. Meanwhile, reasonable technological parameters chosen from theoretical analysis is in good agreement with those obtained from experimental results.
