Dissimilar metal joining between 5A02 aluminum alloy and H62 brass sheets was conducted by gas tungsten arc welding with Zn-15% Al and Al-12% Si flux-cored filler wires. The microstructure in the weld and distribution...Dissimilar metal joining between 5A02 aluminum alloy and H62 brass sheets was conducted by gas tungsten arc welding with Zn-15% Al and Al-12% Si flux-cored filler wires. The microstructure in the weld and distribution of major alloying elements in the intelfacial layer were examined, and the tensile strength of the resultant joints was measured. Pores appeared in the weld made with Zn-15% Al flax-cored filler wire, the interracial layer mainly consisted of AlCu phase, and the specimens fractured through the weld with tensile strength of 129 MPa. When Al-12% Si flux-cored filler wire was used, Cu diffused into the weld and Al2 Cu phase formed, and the specimens fractured along the interfacial layer with tensile strength of 122 MPa.展开更多
Micro welding of dissimilar metals can meet many performance requirements for modern engineering structures. In this experiment, laser micro welding of copper-aluminum dissimilar metals was conducted with an HWLW-300A...Micro welding of dissimilar metals can meet many performance requirements for modern engineering structures. In this experiment, laser micro welding of copper-aluminum dissimilar metals was conducted with an HWLW-300A energy negative feedback Nd:YAG pulse laser. By using the overlap welding method with copper on aluminum, with the laser energy being distributed unevenly, good weld joints were obtained. In this paper, the welding mechanism was analyzed from aspects such as welding temperature and the specific heat capacity of the solid metal. Existing defects were identified, and a feasible improvement scheme was proposed.展开更多
Joining Mg to Al is challenging because of the deterioration of mechanical properties caused by the formation of intermetallic compounds(IMCs) at the Mg/Al interface. This study aims to improve the mechanical properti...Joining Mg to Al is challenging because of the deterioration of mechanical properties caused by the formation of intermetallic compounds(IMCs) at the Mg/Al interface. This study aims to improve the mechanical properties of welded samples by preventing the fracture location at the Mg/Al interface. Friction stir welding was performed to join Mg to Al at different rotational and travel speeds. The microstructure of the welded samples showed the IMCs layers containing Al12Mg17(γ) and Al3Mg2(β) at the welding zone with a thickness(< 3.5 μm). Mechanical properties were mainly affected by the thickness of the IMCs, which was governed by welding parameters. The highest tensile strength was obtained at 600 r/min and 40 mm/min with a welding efficiency of 80%. The specimens could fracture along the boundary at the thermo-mechanically affected zone in the Mg side of the welded joint.展开更多
This paper mainly concentrated on the feasibility of friction stir welding of dissimilar metal of aluminum alloy to copper (I2) and a preliminary analysis of welding parameters influencing on the microstructures and...This paper mainly concentrated on the feasibility of friction stir welding of dissimilar metal of aluminum alloy to copper (I2) and a preliminary analysis of welding parameters influencing on the microstructures and properties of joint was carried out. The results indicated that the thickness of workpiece played an important role in the welding parameters which could succeed in the friction stir welding of dissimilar metal of copper to aluminum alloy, and the parameters were proved to be a narrow choice. The interfacial region between copper and aluminum in the dissimilar joint was not uniformly mixed, constituted with part of incomplete mixing zone, complete mixing zone, dispersion zone and the most region' s boundary was obvious. Meantime a kind banded structure with inhomogeneous width was formed. The intermetallic compounds generated during friction stir welding in the interfacial region were mainly CugAl4, Al2Cu etc, and their hardness was higher than oihers.展开更多
Dissimilar aluminum alloys AA2024-T365 and AA5083-H111 were welded by friction stir process. Welding parameters such as tool rotational speed (900, 1120 and 1400 rpm), weld speeds (16, 40 and 80 mm/min) and tool pin p...Dissimilar aluminum alloys AA2024-T365 and AA5083-H111 were welded by friction stir process. Welding parameters such as tool rotational speed (900, 1120 and 1400 rpm), weld speeds (16, 40 and 80 mm/min) and tool pin profiles (square, triangular and stepped) were used to weld many joints to study their effect on the mechanical properties of the joint. Also, different locations of the material were studied as other parameter. The mechanical properties were evaluated using tensile and hardness tests. The microstructure characterization of the processed alloys was carried out using optical microscopy. Macro and microstructures of parent and welded specimens indicated that the weld parameters have a significant effect on mechanical and microstructural properties of the welds. However, defect-free as well as higher strength was obtained at higher speed of 80 mm/min.展开更多
Dissimilar friction stir welding between 5052 Al alloy and AZ31 Mg alloy with the plate thickness of 6 mm was investigated.Sound weld was obtained at rotation speed of 600 r/min and welding speed of 40 mm/min.Compared...Dissimilar friction stir welding between 5052 Al alloy and AZ31 Mg alloy with the plate thickness of 6 mm was investigated.Sound weld was obtained at rotation speed of 600 r/min and welding speed of 40 mm/min.Compared with the base materials,the microstructure of the stir zone is greatly refined.Complex flow pattern characterized by intercalation lamellae is formed in the stir zone.Microhardness measurement of the dissimilar welds presents an uneven distribution due to the complicated microstructure of the weld,and the maximum value of microhardness in the stir zone is twice higher than that of the base materials. The tensile fracture position locates at the advancing side(aluminum side),where the hardness distribution of weld shows a sharp decrease from the stir zone to 5052 base material.展开更多
In the present work,the effect of process parameters on joining of AZ91 Mg alloy and Al6063 aluminum alloy sheets during friction stir welding(FSP)was studied.A successful joint was achieved at 1100 r.p.m.tool rotatio...In the present work,the effect of process parameters on joining of AZ91 Mg alloy and Al6063 aluminum alloy sheets during friction stir welding(FSP)was studied.A successful joint was achieved at 1100 r.p.m.tool rotational speed and 25 mm/min tool travel speed.Combination of tool rotational speed and tool travel speed has observed a profound effect on the material flow mechanisms at the nugget zone.From the microstructural studies,the joint formation was observed as mainly due to mechanical mixing of the materials.The level of metallurgical continuity at the nugget zone was observed as poor and a sharp interface at the joint was noticed.The microhardness measurements across the weld joint also revealed the lack of establishment of a perfect metallurgical bonding.X-ray diffraction analysis of weld zone showed presence of both magnesium and aluminum.Hence from the preliminary observations,it can be understood that the joining of AZ91 Mg alloy and Al6063 alloy can be achieved by FSP;however,complex issues in material mixing still need further investigations.展开更多
Mechanical properties and material mixing patterns of friction stir spot welded (FSSW) joints of dissimilar aluminum alloys were investigated.Two aluminum alloys typically used in automotive applications,5052-H32 and ...Mechanical properties and material mixing patterns of friction stir spot welded (FSSW) joints of dissimilar aluminum alloys were investigated.Two aluminum alloys typically used in automotive applications,5052-H32 and 6061-T6,were selected.During the experiment,the process parameters including the z-axis force and torque histories were measured as a function of the tool displacement.The mechanical properties were investigated by microhardness measurements of the joint,and the material mixing in the stir zone was investigated by EPMA.The experimental results illustrate different process parameter histories,material mixing in the stir zone and material properties including microhardness distributions for FSSW joints of dissimilar aluminum alloys,likely due to different mechanical behaviors of the selected aluminum alloys in the FSSW process temperature range.展开更多
Aluminium alloys generally present low weldability by traditional fusion welding process.Development of the friction stir welding(FSW)has provided an alternative improved way of producing aluminium joints in a faster ...Aluminium alloys generally present low weldability by traditional fusion welding process.Development of the friction stir welding(FSW)has provided an alternative improved way of producing aluminium joints in a faster and reliable manner.The quality of a weld joint is stalwartly influenced by process parameter used during welding.An approach to develop a mathematical model was studied for predicting and optimizing the process parameters of dissimilar aluminum alloy(AA6351 T6 AA5083 H111)joints by incorporating the FSW process parameters such as tool pin profile,tool rotational speed welding speed and axial force.The effects of the FSW process parameters on the ultimate tensile strength(UTS)of friction welded dissimilar joints were discussed.Optimization was carried out to maximize the UTS using response surface methodology(RSM)and the identified optimum FSW welding parameters were reported.展开更多
Aluminium-copper hybrid parts, as a substitution to copper parts, result in weight and cost reduction, and are relevant in applications related to the electronic, heating and cooling sector. However, aluminium to copp...Aluminium-copper hybrid parts, as a substitution to copper parts, result in weight and cost reduction, and are relevant in applications related to the electronic, heating and cooling sector. However, aluminium to copper joined by thermal welding processes presents challenges in terms of achieving good joint quality. This is attributed to their dissimilar mechanical and thermal properties which result in large stress gradients during heating. This study investigated joining of aluminium to copper sheets by electromagnetic pulse welding, which is a solid-state process that uses electromagnetic forces for joining of dissimilar materials. Hybrid sheet welds were obtained for all parameters conditions, selected according to a Taguchi L18 design. The structural and mechanical characteristics were examined and related to the welding parameters by means of a Pareto analysis and response graphs. The welded zone started with a wavy interface with interfacial layers and defects and evolved to a flat interface without interfacial layers. The maximum transferable force depended on the minimum specimen thickness and the strength of the hybrid sheet weld. In case of aluminium sheet thickness reduction, the maximum transferable force was linearly correlated with the aluminium sheet thickness. High quality joints were obtained for no aluminium sheet thickness reduction and for a sheet weld strength which was at least as high as that of the base material. The most effective way to increase the transferable force was to lower the initial gap and to increase the free length, which resulted in no aluminium sheet thickness reduction. Alternatively, the use of a rounded spacer decreased the effect of the aluminium sheet thickness on the transferable force. An increase in weld width was achieved for an increase in capacitor charging energy and gap, whereas an increase in weld length was obtained for a decrease in gap. An increase in weld width did not necessarily result in an increase in the transferable force. In the regarded cases, a hybrid sheet with narrow weld width could therefore have higher quality.展开更多
Friction stir welding(FSW) was used to weld dissimilar Al-Mg-Si/Al-Zn-Mg aluminum alloys in this work.Influences of sheet configuration on microstructure and mechanical properties of the joints were mainly discussed...Friction stir welding(FSW) was used to weld dissimilar Al-Mg-Si/Al-Zn-Mg aluminum alloys in this work.Influences of sheet configuration on microstructure and mechanical properties of the joints were mainly discussed.Results showed that rather different joint cross sections were obtained when using different sheet configurations.Coarser β' phases can be observed at the heat affected zone(HAZ) of the Al-Mg-Si alloy side,which was the main factor affecting the tensile properties and the fatigue properties.Tensile strengths of the dissimilar Al-Mg-Si/Al-Zn-Mg joints using both configurations were higher than that of the Al-Mg-Si FSW joint.When the Al-Zn-Mg alloy was located at the advancing side(AS),the joints owned better fatigue properties due to the bridging effect of the big secondary phase particles.展开更多
Widespread use of aluminum alloys for the fabrication of car body parts is conditional to the use of appropriate welding methods,especially if dissimilar welding must be performed with automotive steel grades.Friction...Widespread use of aluminum alloys for the fabrication of car body parts is conditional to the use of appropriate welding methods,especially if dissimilar welding must be performed with automotive steel grades.Friction stir welding(FSW)is considered to be a reasonable solution to obtain sound aluminum-steel joints.In this context,this work studies the effects of tool position and force control in dissimilar friction stir welding of AA6061 aluminum alloy on DC05 low carbon steel in lap joint configuration,also assessing proper welding parameter settings.Naked eye and scanning electron microscopy(SEM)have been used to detect macroscopic and microscopic defects in joints,as well as to determine the type of intermixture between aluminum and steel.The joint strength of sound joints has been assessed by shear tension test.Results point out that tool force control allows for obtaining joints with better quality and strength in a wider range of process parameters.A process window has been determined for tool force conditions to have joints with adequate strength for automotive purposes.展开更多
Cyclic deformation behavior of friction-stir-welded dissimilar AA2024-T351 to AA7075-T65 aluminum alloy joints was evaluated via stepwise tests at different strain rates,along with transmission electron microscopy exa...Cyclic deformation behavior of friction-stir-welded dissimilar AA2024-T351 to AA7075-T65 aluminum alloy joints was evaluated via stepwise tests at different strain rates,along with transmission electron microscopy examinations to characterize the precipitates required to assess internal stresses.Electron backscatter diffraction was employed to observe the inhomogeneous microstructures of the FSWed joints.Strain localization appeared in the heat affected zone(HAZ)of AA2024 side.After cyclic deformation of 500 cycles at a total strain amplitude of 0.5%,the strength of the dissimilar joints resumed basically to that of AA2024 base material.And the AA2024 HAZ was obviously hardened,which should be attributed to the introduced dislocations during cyclic deformation process.Cyclic hardening capacity of the joints increased with decreasing strain rate.展开更多
This study focuses on the bonding interface characteristics and mechanical properties of the bobbin tool friction stir welded dissimilar AA6056 and AA2219 aluminum alloy joints using diff erent welding speeds.Voids ar...This study focuses on the bonding interface characteristics and mechanical properties of the bobbin tool friction stir welded dissimilar AA6056 and AA2219 aluminum alloy joints using diff erent welding speeds.Voids arise solely in the stir zone at the AA2219 side.A distinct boundary with limited material mixing develops at the middle section of the bonding interface,while excellent material mixing with an irregularly jagged pattern forms at the top and bottom sections of the bonding interface.Increasing the welding speed,the material mixing is rarely changed at the middle section in comparison with the bottom section.Furthermore,a small diff erence between Guinier–Preston dissolution and Q phase precipitation leads to rare change of hardness in the heat aff ected zone(HAZ)at the AA6056 side.The increased hardness of the HAZ at the AA2219 side is attributed to avoidance of the dissolution ofθ’’phase precipitates.A maximum tensile strength of 181 MPa is obtained at 300 mm min-1.Fractures occur at the AA6056 side near the top and bottom surfaces and at the bonding interface in the middle section of the joints.The regions close to the top and bottom surfaces of the joints show a better ductility.展开更多
基金Acknowledgements This work was financially supported by the National Natural Science Foundation of China ( Grant No. 50904012 ) and Natural Science Foundation of Liaoning Province (Grant No. 20092152).
文摘Dissimilar metal joining between 5A02 aluminum alloy and H62 brass sheets was conducted by gas tungsten arc welding with Zn-15% Al and Al-12% Si flux-cored filler wires. The microstructure in the weld and distribution of major alloying elements in the intelfacial layer were examined, and the tensile strength of the resultant joints was measured. Pores appeared in the weld made with Zn-15% Al flax-cored filler wire, the interracial layer mainly consisted of AlCu phase, and the specimens fractured through the weld with tensile strength of 129 MPa. When Al-12% Si flux-cored filler wire was used, Cu diffused into the weld and Al2 Cu phase formed, and the specimens fractured along the interfacial layer with tensile strength of 122 MPa.
文摘Micro welding of dissimilar metals can meet many performance requirements for modern engineering structures. In this experiment, laser micro welding of copper-aluminum dissimilar metals was conducted with an HWLW-300A energy negative feedback Nd:YAG pulse laser. By using the overlap welding method with copper on aluminum, with the laser energy being distributed unevenly, good weld joints were obtained. In this paper, the welding mechanism was analyzed from aspects such as welding temperature and the specific heat capacity of the solid metal. Existing defects were identified, and a feasible improvement scheme was proposed.
基金Universiti Kebangsaan Malaysia for supporting this research project through the research funding (AP-2015-016)
文摘Joining Mg to Al is challenging because of the deterioration of mechanical properties caused by the formation of intermetallic compounds(IMCs) at the Mg/Al interface. This study aims to improve the mechanical properties of welded samples by preventing the fracture location at the Mg/Al interface. Friction stir welding was performed to join Mg to Al at different rotational and travel speeds. The microstructure of the welded samples showed the IMCs layers containing Al12Mg17(γ) and Al3Mg2(β) at the welding zone with a thickness(< 3.5 μm). Mechanical properties were mainly affected by the thickness of the IMCs, which was governed by welding parameters. The highest tensile strength was obtained at 600 r/min and 40 mm/min with a welding efficiency of 80%. The specimens could fracture along the boundary at the thermo-mechanically affected zone in the Mg side of the welded joint.
基金This project is supported by National Natural Science Foundation of China ( NSFC)(10577010)
文摘This paper mainly concentrated on the feasibility of friction stir welding of dissimilar metal of aluminum alloy to copper (I2) and a preliminary analysis of welding parameters influencing on the microstructures and properties of joint was carried out. The results indicated that the thickness of workpiece played an important role in the welding parameters which could succeed in the friction stir welding of dissimilar metal of copper to aluminum alloy, and the parameters were proved to be a narrow choice. The interfacial region between copper and aluminum in the dissimilar joint was not uniformly mixed, constituted with part of incomplete mixing zone, complete mixing zone, dispersion zone and the most region' s boundary was obvious. Meantime a kind banded structure with inhomogeneous width was formed. The intermetallic compounds generated during friction stir welding in the interfacial region were mainly CugAl4, Al2Cu etc, and their hardness was higher than oihers.
文摘Dissimilar aluminum alloys AA2024-T365 and AA5083-H111 were welded by friction stir process. Welding parameters such as tool rotational speed (900, 1120 and 1400 rpm), weld speeds (16, 40 and 80 mm/min) and tool pin profiles (square, triangular and stepped) were used to weld many joints to study their effect on the mechanical properties of the joint. Also, different locations of the material were studied as other parameter. The mechanical properties were evaluated using tensile and hardness tests. The microstructure characterization of the processed alloys was carried out using optical microscopy. Macro and microstructures of parent and welded specimens indicated that the weld parameters have a significant effect on mechanical and microstructural properties of the welds. However, defect-free as well as higher strength was obtained at higher speed of 80 mm/min.
基金Project(B01B7070270)supported by the Scientific Research Foundation for the Returned Overseas Chinese Scholars,State Education Ministry,China
文摘Dissimilar friction stir welding between 5052 Al alloy and AZ31 Mg alloy with the plate thickness of 6 mm was investigated.Sound weld was obtained at rotation speed of 600 r/min and welding speed of 40 mm/min.Compared with the base materials,the microstructure of the stir zone is greatly refined.Complex flow pattern characterized by intercalation lamellae is formed in the stir zone.Microhardness measurement of the dissimilar welds presents an uneven distribution due to the complicated microstructure of the weld,and the maximum value of microhardness in the stir zone is twice higher than that of the base materials. The tensile fracture position locates at the advancing side(aluminum side),where the hardness distribution of weld shows a sharp decrease from the stir zone to 5052 base material.
文摘In the present work,the effect of process parameters on joining of AZ91 Mg alloy and Al6063 aluminum alloy sheets during friction stir welding(FSP)was studied.A successful joint was achieved at 1100 r.p.m.tool rotational speed and 25 mm/min tool travel speed.Combination of tool rotational speed and tool travel speed has observed a profound effect on the material flow mechanisms at the nugget zone.From the microstructural studies,the joint formation was observed as mainly due to mechanical mixing of the materials.The level of metallurgical continuity at the nugget zone was observed as poor and a sharp interface at the joint was noticed.The microhardness measurements across the weld joint also revealed the lack of establishment of a perfect metallurgical bonding.X-ray diffraction analysis of weld zone showed presence of both magnesium and aluminum.Hence from the preliminary observations,it can be understood that the joining of AZ91 Mg alloy and Al6063 alloy can be achieved by FSP;however,complex issues in material mixing still need further investigations.
基金Project supported by Development Program of Local Science Park by the ULSAN Metropolitan City and the MESTProject supported by Basic Science Research Program,the National Research Foundation of Korea(2011-0026072)
文摘Mechanical properties and material mixing patterns of friction stir spot welded (FSSW) joints of dissimilar aluminum alloys were investigated.Two aluminum alloys typically used in automotive applications,5052-H32 and 6061-T6,were selected.During the experiment,the process parameters including the z-axis force and torque histories were measured as a function of the tool displacement.The mechanical properties were investigated by microhardness measurements of the joint,and the material mixing in the stir zone was investigated by EPMA.The experimental results illustrate different process parameter histories,material mixing in the stir zone and material properties including microhardness distributions for FSSW joints of dissimilar aluminum alloys,likely due to different mechanical behaviors of the selected aluminum alloys in the FSSW process temperature range.
文摘Aluminium alloys generally present low weldability by traditional fusion welding process.Development of the friction stir welding(FSW)has provided an alternative improved way of producing aluminium joints in a faster and reliable manner.The quality of a weld joint is stalwartly influenced by process parameter used during welding.An approach to develop a mathematical model was studied for predicting and optimizing the process parameters of dissimilar aluminum alloy(AA6351 T6 AA5083 H111)joints by incorporating the FSW process parameters such as tool pin profile,tool rotational speed welding speed and axial force.The effects of the FSW process parameters on the ultimate tensile strength(UTS)of friction welded dissimilar joints were discussed.Optimization was carried out to maximize the UTS using response surface methodology(RSM)and the identified optimum FSW welding parameters were reported.
文摘Aluminium-copper hybrid parts, as a substitution to copper parts, result in weight and cost reduction, and are relevant in applications related to the electronic, heating and cooling sector. However, aluminium to copper joined by thermal welding processes presents challenges in terms of achieving good joint quality. This is attributed to their dissimilar mechanical and thermal properties which result in large stress gradients during heating. This study investigated joining of aluminium to copper sheets by electromagnetic pulse welding, which is a solid-state process that uses electromagnetic forces for joining of dissimilar materials. Hybrid sheet welds were obtained for all parameters conditions, selected according to a Taguchi L18 design. The structural and mechanical characteristics were examined and related to the welding parameters by means of a Pareto analysis and response graphs. The welded zone started with a wavy interface with interfacial layers and defects and evolved to a flat interface without interfacial layers. The maximum transferable force depended on the minimum specimen thickness and the strength of the hybrid sheet weld. In case of aluminium sheet thickness reduction, the maximum transferable force was linearly correlated with the aluminium sheet thickness. High quality joints were obtained for no aluminium sheet thickness reduction and for a sheet weld strength which was at least as high as that of the base material. The most effective way to increase the transferable force was to lower the initial gap and to increase the free length, which resulted in no aluminium sheet thickness reduction. Alternatively, the use of a rounded spacer decreased the effect of the aluminium sheet thickness on the transferable force. An increase in weld width was achieved for an increase in capacitor charging energy and gap, whereas an increase in weld length was obtained for a decrease in gap. An increase in weld width did not necessarily result in an increase in the transferable force. In the regarded cases, a hybrid sheet with narrow weld width could therefore have higher quality.
基金supported by the International S&T Cooperation Program of China(ISTCP) under grant No.2012DFR50580
文摘Friction stir welding(FSW) was used to weld dissimilar Al-Mg-Si/Al-Zn-Mg aluminum alloys in this work.Influences of sheet configuration on microstructure and mechanical properties of the joints were mainly discussed.Results showed that rather different joint cross sections were obtained when using different sheet configurations.Coarser β' phases can be observed at the heat affected zone(HAZ) of the Al-Mg-Si alloy side,which was the main factor affecting the tensile properties and the fatigue properties.Tensile strengths of the dissimilar Al-Mg-Si/Al-Zn-Mg joints using both configurations were higher than that of the Al-Mg-Si FSW joint.When the Al-Zn-Mg alloy was located at the advancing side(AS),the joints owned better fatigue properties due to the bridging effect of the big secondary phase particles.
文摘Widespread use of aluminum alloys for the fabrication of car body parts is conditional to the use of appropriate welding methods,especially if dissimilar welding must be performed with automotive steel grades.Friction stir welding(FSW)is considered to be a reasonable solution to obtain sound aluminum-steel joints.In this context,this work studies the effects of tool position and force control in dissimilar friction stir welding of AA6061 aluminum alloy on DC05 low carbon steel in lap joint configuration,also assessing proper welding parameter settings.Naked eye and scanning electron microscopy(SEM)have been used to detect macroscopic and microscopic defects in joints,as well as to determine the type of intermixture between aluminum and steel.The joint strength of sound joints has been assessed by shear tension test.Results point out that tool force control allows for obtaining joints with better quality and strength in a wider range of process parameters.A process window has been determined for tool force conditions to have joints with adequate strength for automotive purposes.
基金financially supported by the National Natural Science Foundation of China(No.51574196)the Natural Sciences and Engineering Research Council of Canada(NSERC)in the form of an international research collaboration+3 种基金the financial support by Premier’s Research Excellence Award(PREA)NSERC-Discovery Accelerator Supplement(DAS)AwardCanada Foundation for Innovation(CFI)Ryerson Research Chair(RRC)program。
文摘Cyclic deformation behavior of friction-stir-welded dissimilar AA2024-T351 to AA7075-T65 aluminum alloy joints was evaluated via stepwise tests at different strain rates,along with transmission electron microscopy examinations to characterize the precipitates required to assess internal stresses.Electron backscatter diffraction was employed to observe the inhomogeneous microstructures of the FSWed joints.Strain localization appeared in the heat affected zone(HAZ)of AA2024 side.After cyclic deformation of 500 cycles at a total strain amplitude of 0.5%,the strength of the dissimilar joints resumed basically to that of AA2024 base material.And the AA2024 HAZ was obviously hardened,which should be attributed to the introduced dislocations during cyclic deformation process.Cyclic hardening capacity of the joints increased with decreasing strain rate.
基金the support provided by the China Scholarship Council(No.201806290070)the fund by the State Key Laboratory of Solidifi cation Processing in NWPU(No.2019-QZ-01)。
文摘This study focuses on the bonding interface characteristics and mechanical properties of the bobbin tool friction stir welded dissimilar AA6056 and AA2219 aluminum alloy joints using diff erent welding speeds.Voids arise solely in the stir zone at the AA2219 side.A distinct boundary with limited material mixing develops at the middle section of the bonding interface,while excellent material mixing with an irregularly jagged pattern forms at the top and bottom sections of the bonding interface.Increasing the welding speed,the material mixing is rarely changed at the middle section in comparison with the bottom section.Furthermore,a small diff erence between Guinier–Preston dissolution and Q phase precipitation leads to rare change of hardness in the heat aff ected zone(HAZ)at the AA6056 side.The increased hardness of the HAZ at the AA2219 side is attributed to avoidance of the dissolution ofθ’’phase precipitates.A maximum tensile strength of 181 MPa is obtained at 300 mm min-1.Fractures occur at the AA6056 side near the top and bottom surfaces and at the bonding interface in the middle section of the joints.The regions close to the top and bottom surfaces of the joints show a better ductility.