Ni-based superalloys are one of the most important materials employed in high-temperature applications within the aerospace and nuclear energy industries and in gas turbines due to their excellent corrosion,radiation,...Ni-based superalloys are one of the most important materials employed in high-temperature applications within the aerospace and nuclear energy industries and in gas turbines due to their excellent corrosion,radiation,fatigue resistance,and high-temperature strength.Linear friction welding(LFW)is a new joining technology with near-net-forming characteristics that can be used for the manu-facture and repair of a wide range of aerospace components.This paper reviews published works on LFW of Ni-based superalloys with the aim of understanding the characteristics of frictional heat generation and extrusion deformation,microstructures,mechanical proper-ties,flash morphology,residual stresses,creep,and fatigue of Ni-based superalloy weldments produced with LFW to enable future optim-um utilization of the LFW process.展开更多
A dynamometer was designed and manufactured to measure the joining force in the linear friction welding process.The error percentages of the dynamometer in the upset(x)and vibration(y)directions were 0.9% and 0.75%,re...A dynamometer was designed and manufactured to measure the joining force in the linear friction welding process.The error percentages of the dynamometer in the upset(x)and vibration(y)directions were 0.9% and 0.75%,respectively.The cross-sensitivity range of the dynamometer was 1.2%—3.3% in the two directions.The precision level satisfies the requirements of the dynamometer test.The joining force of the TC17 and TC11 heterogeneous titanium alloys in the linear friction welding process was used to test the manufactured dynamometer.The test results showed that the upset force was large,but the vibration force showed a smaller change in TC11 during the linear friction welding process.In addition,the upset and vibration forces of the linear friction welding were greater with a short welding time than those with a long welding time.展开更多
TC17 titanium alloy which usually used on the fan and compressor disk were selected.Microstructure and mechanical property of joint were investigated.Microstructure character of different part of joint was analyzed al...TC17 titanium alloy which usually used on the fan and compressor disk were selected.Microstructure and mechanical property of joint were investigated.Microstructure character of different part of joint was analyzed also.Results showed that the joints included three zones,base metal(BM),thermal mechanical affected zone(TMAZ)and weld zone(WZ).The microstructure of joint middle part was equiaxial grains,but the bottom part was the elongated grains.Dynamic recrystallation happened at the weld zone.Tensile test result showed that joint tensile strength equal to that of the TC17 base metal.The average hardness value of the HAZ was 486 HV which was higher than that in the BM and WZ.展开更多
The continuous growth in the manufacture of aerospace components such as blisks has led to an increase in the application of different hybrid materials fabricating methods,and thus the requirements for joining and str...The continuous growth in the manufacture of aerospace components such as blisks has led to an increase in the application of different hybrid materials fabricating methods,and thus the requirements for joining and strengthening of dissimilar welds.According to this goal,selective laser melted(SLM)Inconel718 was joined with forged AD730^(TM)Nickel-based superalloy through linear friction welding(LFW)in this study.Microstructure variation,specifically with respect to secondary phases precipitation was investigated.The microhardness and strengthening mechanisms of the weldment were also studied.The precipitation(volume fraction and size of particles)at different regions of both sides of the weld line was characterized.Close to the weld line,the dissolution ofγ’/γ"and Laves phases and grain refinement occurred which reveals the effects of both compression strain and high temperature on recrystallization and high degree of elemental diffusion in the weld zone(WZ).It is shown that the size,volume fraction,and shape of secondary phases increased and changed(from spherical to long-striped for Laves particles)as we went from the WZ toward the base metal.However,the measured microhardness indicated that the strength of AD730^(TM)alloy depends significantly on the grain size,while strength in SLM Inconel 718 was dominated by shape(or size)and the presence of secondary phases(γ’/γ"and Laves).展开更多
Micro-pore is a very common material defect. In the present paper, the temperature fields of medium carbon steel joints with and without micro-pore defect during linear friction welding (LFW) were investigated by us...Micro-pore is a very common material defect. In the present paper, the temperature fields of medium carbon steel joints with and without micro-pore defect during linear friction welding (LFW) were investigated by using finite element method. The effect of micro-pore defect on the axial shortening of joints during LFW was examined. The x- and y-direction displacements of micro-pore during the LFW process were also studied. In addition, the shape of micro-pore after LFW was observed. The heat conducted from the weld inteace to the specimen interior. The fluctuation range of the temperature curves for the joint with micro-pore is larger than that without micro-pore. Position of micro-pore changes with the change of the friction time. The circular shape of micro-pore becomes oval after welding.展开更多
By monitoring the line voltage and current of the driving motor during linear friction welding ( LFW) of GH4169 superalloy, the frictional power of the rubbing interface between two components to be joined was detec...By monitoring the line voltage and current of the driving motor during linear friction welding ( LFW) of GH4169 superalloy, the frictional power of the rubbing interface between two components to be joined was detected. The data was recorded by a data acquisition card and processed by the LabVIEW software. By analyzing the evolution of frictional power, the joint formation mechanism was discussed. The curves of the measured basic variables (frictional power, axial shortening, interfacial temperature and axial pressure) reflected the characteristics of the LFW process and offered an effective way for welding parameter optimization.展开更多
Abstract Transient stress and strain fields of dissimilar titanium alloys (TCll and TC17 ) joint during linear friction welding ( LFW) were investigated by a two-dimensional model with ABAQUS/Explicit. The results...Abstract Transient stress and strain fields of dissimilar titanium alloys (TCll and TC17 ) joint during linear friction welding ( LFW) were investigated by a two-dimensional model with ABAQUS/Explicit. The results showed that in the X-axis, the maximum compressive stress of 850 MPa occurred in the center zone of friction interface , and the maximum tensile stress of 190 MPa distributed at the flash; in the Y-axis, the maximum compressive stress of 1 261 MPa located at the junction region between the welding fixture and edge of the specimen, and the maximum tensile stress of 320 MPa distributed in the connecting portion between the flash and edge of the specimen. In addition, areas of plastic strain increased gradually during welding process. In the X-axis, tensile strain mainly existed at the heads of the specimens; in the Y-axis, compressive strain mainly occurred at the heads of the specimens.展开更多
By the 3D coupled thermo-mechanical finite element model of linear friction welding of TC4 titanium alloy, the relation between the temperature and the flashes is researched. The numerical simulation results show that...By the 3D coupled thermo-mechanical finite element model of linear friction welding of TC4 titanium alloy, the relation between the temperature and the flashes is researched. The numerical simulation results show that the flashes with the wrinkles appear only when the temperature of material in the friction surface is high enough. The flashes, which are made up of material with high temperature, are squeezed out of the component. The appearance of flashes makes the temperature of material in the friction susface slowly increase or even decrease. Compared with the oscillation frequency and the oscillation amplitude, the friction pressure' s increase can mare easily attain the flashes with the bigger dimensionz.展开更多
Linear friction welding (LFW) is a solid state process for joining metals together. While this process was developed originaUy for titanium alloys (e. g. blisks ) , over the past decade a number of materials were ...Linear friction welding (LFW) is a solid state process for joining metals together. While this process was developed originaUy for titanium alloys (e. g. blisks ) , over the past decade a number of materials were found to be weldable with LFW. In this review, the current status of understanding and development of LFW are presented. Particular emphasis has been given to the modeling of the LFW process. Finally, opportunities for further research and development of LFW are identified.展开更多
The linear friction welding process of Ti6Al4 V was modeled and computed ,for obtaining the residual stresses. Temperature, stress and strain fields were simulated, based on which, the residual stresses were also cah...The linear friction welding process of Ti6Al4 V was modeled and computed ,for obtaining the residual stresses. Temperature, stress and strain fields were simulated, based on which, the residual stresses were also cah'ulated. Simulated resttlts showed that the longitudinal residual stresses were tensile stresses at the bonding interface, and decreased rapidly with the increase of the distance from the bonding interface until turned into compressive stresses. The compressive stresses decreased slowly as the distance increased, and approached to zero finally. The distribution of the transverse residual stresses was similar to that of the longitudinal residual stresses, but showed much smaller values. The residual stresses in one linear friction weld were measured by an X-ray diffrnctometer. The average valwe of errors between computed and measured results was 14. 5 %.展开更多
The microstructures and lap-shear behaviors of friction stir lap linear welded as-extruded 6061 Al alloy to as-cast Mg–3.0Nd–0.2Zn–0.7Zr(wt.%)(NZ30K)alloy joints were examined.Various tool rotation and travel speed...The microstructures and lap-shear behaviors of friction stir lap linear welded as-extruded 6061 Al alloy to as-cast Mg–3.0Nd–0.2Zn–0.7Zr(wt.%)(NZ30K)alloy joints were examined.Various tool rotation and travel speeds were adopted to prepare the joints.The analysis of temperature field indicates that the peak temperature for each sample can reach 450℃,which exceeds the eutectic reaction temperatures of 437℃ and 450℃ according to the binary phase diagram of Al–Mg system.The fierce intermixing can be found at the interface between Al and Mg alloys,forming the intermetallic of Al_(3)Mg_(2).Welds with the rotation speed of 900 rpm and travel speed of 120 mm/min display the highest tensile shear failure load of about 2.24 kN.The value was increased by 13%after the sample was heat treated at 400℃ for 0.5 h.展开更多
The Ti17(a+β)-Ti17(β)dual alloy-dual property blisk produced using Linear Friction Welding(LFW)is considered as high-performance component in advanced aeroengine.However,up to now,microstructure evolution and relati...The Ti17(a+β)-Ti17(β)dual alloy-dual property blisk produced using Linear Friction Welding(LFW)is considered as high-performance component in advanced aeroengine.However,up to now,microstructure evolution and relationship between microstructure and micro mechanical properties of LFWed Ti17(a+β)/Ti17(β)dissimilar joint have not been thoroughly revealed.In this work,complex analyses of the phase transformation mechanisms of the joint are conducted,and phase transformations in individual zones are correlated to their microhardness and nanohardness.Results reveal that a dissolution occurs under high temperatures encountered during LFW,which reduces microhardness of the joint to that of Ti17(a+β)and Ti17(β).In ThermoMechanically Affected Zone of Ti17(a+β)(TMAZ-(a+β))side joint,a large number of nanocrystalline a phases form with different orientations.This microstructure strengthens significantly by fine grains which balances partial softening effect of a dissolution,and increases nanohardness of a phase and microhardness of TMAZ-(a+β).Superlattice metastableβphase precipitates from metastableβin Weld Zone(WZ)during quick cooling following welding,because of short-range diffusion migration of solute atoms,especiallyβstabilizing elements Mo and Cr.The precipitation of the superlattice metastableβphase results in precipitation strengthening,which in turn increases nanohardness of metastableβand microhardness in WZ.展开更多
Numerical simulation and experimental research on Linear Friction Welding(LFW) for GH4169 superalloy were carried out. Based on the joint microstructure and mechanical properties,a suitable welding process was determi...Numerical simulation and experimental research on Linear Friction Welding(LFW) for GH4169 superalloy were carried out. Based on the joint microstructure and mechanical properties,a suitable welding process was determined, which provided an important theoretical basis for the manufacture and repair of aeroengine components such as the superalloy blisk. The results show that the joint strain rate gradually increases with the increase of welding frequency, and the deformation resistance of the thermoplastic metal increases in the welding process, resulting in the interface thermoplastic metal not being extruded in time to form a flash, so the joint shortening amount gradually decreases. The thermoplastic metal in the center of the welding surface is kept at high welding temperature for a long time, resulting in the decrease of the joint strength. The microhardness of the joint shows a “W” distribution perpendicular to the weld, and most of the joints break in the Thermo-Mechanically Affected Zone(TMAZ) with high tensile strength and low elongation.When the welding area is increased without changing the aspect ratio of the welding surface, the interface peak temperature increases gradually, and the joint shortening amount decreases with the increase of the welding interface size.展开更多
Linear friction welding (LFW), as a solid state joining process, has been developed to manufacture and repair blisks in aeroengines. The residual stresses after welding may greatly influence the performance of the w...Linear friction welding (LFW), as a solid state joining process, has been developed to manufacture and repair blisks in aeroengines. The residual stresses after welding may greatly influence the performance of the welded components. In this paper, the distribution of residual stresses in Ti6Al4V joints after LFW was inves- tigated with numerical simulations. The effects of applied forging pressure and temperature field at the end of the oscillating stages on the residual stresses within the joints were investigated. The results show that, the residual tensile stresses at the welded interface in the y-direction are the largest, while the largest compressive stresses being present at the flash root in the z-direction. Furthermore, the forging pressure and temperature field at the end of the oscillating stages strongly affect the magnitude of the residual stresses. The larger forging pressure produced lower residual stresses in the weld plane in all three directions (x-, y-, and z-directions). Larger variance, a, which decides the Gaussian distribution of the temperature field, also yields lower residual stresses. There is good agreement between simulation results and experimental data.展开更多
基金supported by the National Natural Science Foundation of China(Nos.52074228,52305420,and 51875470)the China Postdoctoral Science Foundation(No.2023M742830)the Xi’an Beilin District Science and Technology Planning Project,China(No.GX2349).
文摘Ni-based superalloys are one of the most important materials employed in high-temperature applications within the aerospace and nuclear energy industries and in gas turbines due to their excellent corrosion,radiation,fatigue resistance,and high-temperature strength.Linear friction welding(LFW)is a new joining technology with near-net-forming characteristics that can be used for the manu-facture and repair of a wide range of aerospace components.This paper reviews published works on LFW of Ni-based superalloys with the aim of understanding the characteristics of frictional heat generation and extrusion deformation,microstructures,mechanical proper-ties,flash morphology,residual stresses,creep,and fatigue of Ni-based superalloy weldments produced with LFW to enable future optim-um utilization of the LFW process.
基金supported by the National Natural Science Foundation of China (Nos.51175255 , 51305199)the Excellent Young Talents Fund Key Project of the Anhui Higher Education Institutions of China (No. 2013SQRL089ZD)the Starting Foundation for Talents from HuangShan University of China (No.2013xkjq003)
文摘A dynamometer was designed and manufactured to measure the joining force in the linear friction welding process.The error percentages of the dynamometer in the upset(x)and vibration(y)directions were 0.9% and 0.75%,respectively.The cross-sensitivity range of the dynamometer was 1.2%—3.3% in the two directions.The precision level satisfies the requirements of the dynamometer test.The joining force of the TC17 and TC11 heterogeneous titanium alloys in the linear friction welding process was used to test the manufactured dynamometer.The test results showed that the upset force was large,but the vibration force showed a smaller change in TC11 during the linear friction welding process.In addition,the upset and vibration forces of the linear friction welding were greater with a short welding time than those with a long welding time.
文摘TC17 titanium alloy which usually used on the fan and compressor disk were selected.Microstructure and mechanical property of joint were investigated.Microstructure character of different part of joint was analyzed also.Results showed that the joints included three zones,base metal(BM),thermal mechanical affected zone(TMAZ)and weld zone(WZ).The microstructure of joint middle part was equiaxial grains,but the bottom part was the elongated grains.Dynamic recrystallation happened at the weld zone.Tensile test result showed that joint tensile strength equal to that of the TC17 base metal.The average hardness value of the HAZ was 486 HV which was higher than that in the BM and WZ.
基金The authors gratefully acknowledge the support from the Natural Sciences and Engineering Research Council of Canada(NSERC)2018–03889 through a Discovery Grant.Thanks to Mr.Adrien Lieurey(IMT-Mines Albi ICA-site Albi)for his involvement and fabrication of SLM parts.They would also like to express their gratitude to Aubert&Duval Co.,Dr.Alexandre Devaux,and Prof.Cormier for providing forged AD730™samples and discussions on the definition of the scope of the project.Special thanks to TWI Ltd.for carrying out the LFW of the samples.
文摘The continuous growth in the manufacture of aerospace components such as blisks has led to an increase in the application of different hybrid materials fabricating methods,and thus the requirements for joining and strengthening of dissimilar welds.According to this goal,selective laser melted(SLM)Inconel718 was joined with forged AD730^(TM)Nickel-based superalloy through linear friction welding(LFW)in this study.Microstructure variation,specifically with respect to secondary phases precipitation was investigated.The microhardness and strengthening mechanisms of the weldment were also studied.The precipitation(volume fraction and size of particles)at different regions of both sides of the weld line was characterized.Close to the weld line,the dissolution ofγ’/γ"and Laves phases and grain refinement occurred which reveals the effects of both compression strain and high temperature on recrystallization and high degree of elemental diffusion in the weld zone(WZ).It is shown that the size,volume fraction,and shape of secondary phases increased and changed(from spherical to long-striped for Laves particles)as we went from the WZ toward the base metal.However,the measured microhardness indicated that the strength of AD730^(TM)alloy depends significantly on the grain size,while strength in SLM Inconel 718 was dominated by shape(or size)and the presence of secondary phases(γ’/γ"and Laves).
基金The authors would like to appreeiate the National Natural Science Foundation of China (51005180), the Fok Ying-Tong Educalion Fuundalion for Young Teachers in the Higher Education Institutions of China (131052) , the Fundamental Research Fund of NPU(JC201233) , and the 111 Project of China (B08040).
文摘Micro-pore is a very common material defect. In the present paper, the temperature fields of medium carbon steel joints with and without micro-pore defect during linear friction welding (LFW) were investigated by using finite element method. The effect of micro-pore defect on the axial shortening of joints during LFW was examined. The x- and y-direction displacements of micro-pore during the LFW process were also studied. In addition, the shape of micro-pore after LFW was observed. The heat conducted from the weld inteace to the specimen interior. The fluctuation range of the temperature curves for the joint with micro-pore is larger than that without micro-pore. Position of micro-pore changes with the change of the friction time. The circular shape of micro-pore becomes oval after welding.
基金The work is supported by the National Natural Science Foundation of China (51005180) , the Fok Ying-Tong Education Foundation for Young Teachers in the Higher Education Institutions of China (131052) and Fundamental Research Fund of Northwestern Polytechnical University (JC201233).
文摘By monitoring the line voltage and current of the driving motor during linear friction welding ( LFW) of GH4169 superalloy, the frictional power of the rubbing interface between two components to be joined was detected. The data was recorded by a data acquisition card and processed by the LabVIEW software. By analyzing the evolution of frictional power, the joint formation mechanism was discussed. The curves of the measured basic variables (frictional power, axial shortening, interfacial temperature and axial pressure) reflected the characteristics of the LFW process and offered an effective way for welding parameter optimization.
文摘Abstract Transient stress and strain fields of dissimilar titanium alloys (TCll and TC17 ) joint during linear friction welding ( LFW) were investigated by a two-dimensional model with ABAQUS/Explicit. The results showed that in the X-axis, the maximum compressive stress of 850 MPa occurred in the center zone of friction interface , and the maximum tensile stress of 190 MPa distributed at the flash; in the Y-axis, the maximum compressive stress of 1 261 MPa located at the junction region between the welding fixture and edge of the specimen, and the maximum tensile stress of 320 MPa distributed in the connecting portion between the flash and edge of the specimen. In addition, areas of plastic strain increased gradually during welding process. In the X-axis, tensile strain mainly existed at the heads of the specimens; in the Y-axis, compressive strain mainly occurred at the heads of the specimens.
文摘By the 3D coupled thermo-mechanical finite element model of linear friction welding of TC4 titanium alloy, the relation between the temperature and the flashes is researched. The numerical simulation results show that the flashes with the wrinkles appear only when the temperature of material in the friction surface is high enough. The flashes, which are made up of material with high temperature, are squeezed out of the component. The appearance of flashes makes the temperature of material in the friction susface slowly increase or even decrease. Compared with the oscillation frequency and the oscillation amplitude, the friction pressure' s increase can mare easily attain the flashes with the bigger dimensionz.
基金The work is supported by the National Natural Science Foundation of China (51005180), the Fok Ying-Tong Education Foundation for Young Teachers in the Higher Education Institutions of China ( 131052 ) , the Fundamental Research Funds for the Central Universities (3102014JC02010404), the Fundamental Research Fund of NPU (JC201233), and the 111 Project of China (B08040).
文摘Linear friction welding (LFW) is a solid state process for joining metals together. While this process was developed originaUy for titanium alloys (e. g. blisks ) , over the past decade a number of materials were found to be weldable with LFW. In this review, the current status of understanding and development of LFW are presented. Particular emphasis has been given to the modeling of the LFW process. Finally, opportunities for further research and development of LFW are identified.
文摘The linear friction welding process of Ti6Al4 V was modeled and computed ,for obtaining the residual stresses. Temperature, stress and strain fields were simulated, based on which, the residual stresses were also cah'ulated. Simulated resttlts showed that the longitudinal residual stresses were tensile stresses at the bonding interface, and decreased rapidly with the increase of the distance from the bonding interface until turned into compressive stresses. The compressive stresses decreased slowly as the distance increased, and approached to zero finally. The distribution of the transverse residual stresses was similar to that of the longitudinal residual stresses, but showed much smaller values. The residual stresses in one linear friction weld were measured by an X-ray diffrnctometer. The average valwe of errors between computed and measured results was 14. 5 %.
基金National Science Foundation of China(No.51401125)Shanghai Pujiang Program(No.15PJ1403200)+1 种基金The Special Fund of Jiangsu Province for the Transformation of Scientific and Technological Achievements(BA2016039)Program of Shanghai Subject Chief Scientists(No.14XD1425000).
文摘The microstructures and lap-shear behaviors of friction stir lap linear welded as-extruded 6061 Al alloy to as-cast Mg–3.0Nd–0.2Zn–0.7Zr(wt.%)(NZ30K)alloy joints were examined.Various tool rotation and travel speeds were adopted to prepare the joints.The analysis of temperature field indicates that the peak temperature for each sample can reach 450℃,which exceeds the eutectic reaction temperatures of 437℃ and 450℃ according to the binary phase diagram of Al–Mg system.The fierce intermixing can be found at the interface between Al and Mg alloys,forming the intermetallic of Al_(3)Mg_(2).Welds with the rotation speed of 900 rpm and travel speed of 120 mm/min display the highest tensile shear failure load of about 2.24 kN.The value was increased by 13%after the sample was heat treated at 400℃ for 0.5 h.
基金supported by the National Science and Technology Major Project,China(No.2017-VII-0005-0098)the National Natural Science Foundation of China(No.52105400)+1 种基金the State Key Laboratory of Solidification Processing,China(No.2021-TS-07)the Innovation Foundation for Doctor Dissertation of Northwestern Polytechnical University,China(No.CX2023008)。
文摘The Ti17(a+β)-Ti17(β)dual alloy-dual property blisk produced using Linear Friction Welding(LFW)is considered as high-performance component in advanced aeroengine.However,up to now,microstructure evolution and relationship between microstructure and micro mechanical properties of LFWed Ti17(a+β)/Ti17(β)dissimilar joint have not been thoroughly revealed.In this work,complex analyses of the phase transformation mechanisms of the joint are conducted,and phase transformations in individual zones are correlated to their microhardness and nanohardness.Results reveal that a dissolution occurs under high temperatures encountered during LFW,which reduces microhardness of the joint to that of Ti17(a+β)and Ti17(β).In ThermoMechanically Affected Zone of Ti17(a+β)(TMAZ-(a+β))side joint,a large number of nanocrystalline a phases form with different orientations.This microstructure strengthens significantly by fine grains which balances partial softening effect of a dissolution,and increases nanohardness of a phase and microhardness of TMAZ-(a+β).Superlattice metastableβphase precipitates from metastableβin Weld Zone(WZ)during quick cooling following welding,because of short-range diffusion migration of solute atoms,especiallyβstabilizing elements Mo and Cr.The precipitation of the superlattice metastableβphase results in precipitation strengthening,which in turn increases nanohardness of metastableβand microhardness in WZ.
基金supported by the National Natural Science Foundation of China (Nos. 52305420, 52074228 and 51875470)the China Postdoctoral Science Foundation (No. 2023M742830)the Xi’an Beilin District Science and Technology Planning Project, China (No. GX2349)。
文摘Numerical simulation and experimental research on Linear Friction Welding(LFW) for GH4169 superalloy were carried out. Based on the joint microstructure and mechanical properties,a suitable welding process was determined, which provided an important theoretical basis for the manufacture and repair of aeroengine components such as the superalloy blisk. The results show that the joint strain rate gradually increases with the increase of welding frequency, and the deformation resistance of the thermoplastic metal increases in the welding process, resulting in the interface thermoplastic metal not being extruded in time to form a flash, so the joint shortening amount gradually decreases. The thermoplastic metal in the center of the welding surface is kept at high welding temperature for a long time, resulting in the decrease of the joint strength. The microhardness of the joint shows a “W” distribution perpendicular to the weld, and most of the joints break in the Thermo-Mechanically Affected Zone(TMAZ) with high tensile strength and low elongation.When the welding area is increased without changing the aspect ratio of the welding surface, the interface peak temperature increases gradually, and the joint shortening amount decreases with the increase of the welding interface size.
基金Acknowledgements The authors would like to acknowledge the financial support from the National Natural Science Foundation of China (Grant No. 51405389), the Fundamental Research Funds for the Central Universities (Grant No. 3102014JC02010404) and the Research Fund of the State Key Laboratory of Solidification Processing (Grant No. 122-QZ-2015).
文摘Linear friction welding (LFW), as a solid state joining process, has been developed to manufacture and repair blisks in aeroengines. The residual stresses after welding may greatly influence the performance of the welded components. In this paper, the distribution of residual stresses in Ti6Al4V joints after LFW was inves- tigated with numerical simulations. The effects of applied forging pressure and temperature field at the end of the oscillating stages on the residual stresses within the joints were investigated. The results show that, the residual tensile stresses at the welded interface in the y-direction are the largest, while the largest compressive stresses being present at the flash root in the z-direction. Furthermore, the forging pressure and temperature field at the end of the oscillating stages strongly affect the magnitude of the residual stresses. The larger forging pressure produced lower residual stresses in the weld plane in all three directions (x-, y-, and z-directions). Larger variance, a, which decides the Gaussian distribution of the temperature field, also yields lower residual stresses. There is good agreement between simulation results and experimental data.