Beijing FSW Technology Co.

Chaoyang, China

Beijing FSW Technology Co.

Chaoyang, China

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Cao J.Y.,Shanghai JiaoTong University | Wang M.,Shanghai JiaoTong University | Kong L.,Shanghai JiaoTong University | Zhao H.X.,Beijing FSW Technology Co. | Chai P.,Beijing FSW Technology Co.
Materials Characterization | Year: 2017

The evolution of microstructure, texture and mechanical properties during refill friction stir spot welding (RFSSW) of 6061-T6 alloy was investigated in the present paper. The Electron backscattering diffraction results revealed that a significant volume of A/-A, and B/-B component of shear textures was formed in the weld. The sleeve inner wall governed the formation of shear texture beneath the sleeve and pin. Whereas, the shear texture at the sleeve periphery was associated with the material flow when material was discharged from the bottom of the thread on the rotating sleeve. The microstructure evolution in the RFSSW of 6061-T6 alloy was dominated by continue recrystallization. However, the grain boundary bulging and presence of cube texture indicated that the discontinue recrystallization also participate in the grain evolution. The tensile shear strength had a negative correlation with the hook height. © 2017 Elsevier Inc.


Xu X.,Tianjin University of Technology | Yang X.,Tianjin University of Technology | Zhou G.,Tianjin University of Technology | Tong J.,Beijing FSW Technology Ltd Company
Materials and Design | Year: 2012

Microstructural features and fatigue properties of friction stir lap-welded joints for AA6061-T6 alloy are investigated and the influences of single pass welding (SPW) or double pass welding (DPW), hooking defects and fatigue stress ratio on the fatigue properties are analyzed. It is found that the fatigue strengths of FSW lap-welded joints are obviously lower than that of the fusion lap-welded joints of IIW FAT22 and only approximately correspond and close to the IIW FAT12 design curve. The higher fatigue stress ratio R will lead to the decrease of the fatigue strength of lap-welded joints. The existence of hooking defects is the key factor to reduce the fatigue strengths. Fatigue cracks always initiate at the tip of hooking defect in the RS of SPW and AS of DPW joints respectively. The severity of hooking defects and the quality of lap-welds could not be improved by the DPW process as compared with the SPW process. The fatigue strength Δσm and Δσk (R=0.1) of DPW joints will be 21.26% and 17.88% lower than that of SPW joints respectively. The fracture of lap-welded joints exhibits multiple crack initiations from the tips of the hooking locations, and the crack propagation shows some brittle fracture and is mainly characterized by the fatigue striations. The locations of crack initiation and the amount of secondary cracks in DPW joints are more than that of in the SPW joints which leading to the lower fatigue properties. The ductile fracture mode is obviously shown in the final fracture zone with deep-hole type dimples in the SPW joints but shallow-hole type dimples in the DPW joints. © 2011 Elsevier Ltd.


Wang L.,Shanghai JiaoTong University | Qu J.,Shanghai JiaoTong University | Chen L.,Shanghai JiaoTong University | Meng Q.,Beijing FSW Technology Co. | And 4 more authors.
Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science | Year: 2015

Friction-stir processing (FSP) is used to prepare Ti-35Nb-2Ta-3Zr alloys via different processing routes. Dislocation walls and tangles, deformation-induced α″ martensite, and deformation-induced ω phase are observed. The dominant deformation mechanisms are altered from deformation-induced α″ martensitic transformation and dislocation walls to twinning upon increasing the FSP passes. A reverse deformation-induced ω to β transformation and de-twinning process are observed together with grain refinement to the nanoscale. Meanwhile, compressive distortions along [0001]ω direction are favorable for the transformation from ω to β. © 2015 The Minerals, Metals & Materials Society and ASM International


Dong J.,Beijing Institute of Technology | Dong J.,Beijing FSW Technology Co. | Nie X.,Hubei Sanjiang Aerospace Hongyang Electromechanical Co. | Yan J.,Hubei Sanjiang Aerospace Hongyang Electromechanical Co. | And 4 more authors.
Hanjie Xuebao/Transactions of the China Welding Institution | Year: 2013

Friction-stir welding (FSW) of 6082 aluminum alloy was welded by conventional FSW and bobbin-tool FSW. Microstructure and mechanical performance of the as-prepared joints samples were examined. Some inside-out onion rings can be observed in the cross section of bobbin-tool FSW joints samples in microstructure analysis. Microstructure of nugget and TMAZ are obviously different, which shows the evolution of the microstructure. The results indicate that the general mechanical properties of samples prepared by conventional FSW are better than that by bobbin-tool FSW. Sample prepared by bobbin-tool FSW has a finer average grain size than that by conventional FSW. The cavities in the fracture appearance of bobbin-tool FSW joint sample are shallower and there are some smooth platform which are similar to the quasi-cleavage crack near these cavities. While the deeper cavities can be observed in the fracture appearance of conventional FSW joint sample. The lowest hardness point of bobbin-tool AA 6082 FSW joint sample is located in the TMAZ, and hardness in the upper WNZ zone is the highest.


Dong C.,Beijing Institute of Technology | Dong C.,Beijing FSW Technology Co. | Dong J.,Beijing Institute of Technology | Dong J.,Beijing FSW Technology Co. | And 5 more authors.
Hanjie Xuebao/Transactions of the China Welding Institution | Year: 2012

Friction-stir welding (FSW) of 12-mm-thick plates of 6082 Al was conducted by bobbin-tool. Microstructure and potentiodynamic polarization behavior were examined by optical microscope and CHI660A three-electrode electrochemical workstation. The results indicated that the microstructure of the weld was remarkably reshaped under the condition of the stir-pin rotation speed 600 r/min, travel speed 300 mm/min and tilt angle 0° of the stirring tool. The equiaxed grain microstructures were formed due to dynamical recrystallization in the nugget zone. The corrosion test results showed that the pitting corrosion of base material was more severe than that of bobbin-tool FSW weld, and the corrosion morphology was much rough than that of bobbin-tool FSW weld. The corrosion potential of the weld was positive and higher than that of parent material. The corrosion current density of bobbin-tool FSW weld was lower than that of parent material.


Xu W.F.,Northwestern Polytechnical University | Liu J.H.,Northwestern Polytechnical University | Chen D.L.,Ryerson University | Luan G.H.,Beijing FSW Technology Ltd Company
International Journal of Advanced Manufacturing Technology | Year: 2014

Strain-controlled low-cycle fatigue tests and microstructural evaluation were performed on a friction stir welded 2219-T62 aluminum alloy with varying welding parameters and cooling conditions. Cyclic hardening of friction stir welded joints was appreciably stronger than that of the base material. The cyclic stress amplitude increased, and plastic strain amplitude and fatigue lifetime slightly decreased with increasing welding speed from 60 to 200 mm/min but were only weakly dependent of the rotational rate between 300 and 1,000 rpm with air cooling. Friction stir welded joints with water cooling had higher stress amplitude and fatigue life than that with air cooling. Fatigue failure of the joint occurred in the HAZ where the soft zone was present, with crack initiation from the specimen surface or near-surface defect and crack propagation characterized by typical fatigue striations. © 2014 Springer-Verlag London.


Xu W.,Northwestern Polytechnical University | Liu J.,Northwestern Polytechnical University | Chen D.,Ryerson University | Luan G.,Beijing FSW Technology Ltd Company | Yao J.,Shanghai Aerospace Equipments Manufacturer
Advanced Materials Research | Year: 2011

Microstructures, tensile properties and work hardening behavior of friction stir welded (FSWed) AA2219-T62 aluminum alloy (in its one-third bottom slice of a 20 mm thick plate) were evaluated at different strain rates. While the yield strength was lower in the FSWed joint than in the base metal, the ultimate tensile strength of the FSWed joint approached that of the base metal. In particular the FSW resulted in a significant improvement in the ductility of the alloy due to the prevention of premature failure caused by intergranular cracking along the second-phase boundary related to the presence of the network-like grain boundary phase in the base metal. While stage III and IV hardening occurred after yielding in both base metal and FSWed samples, the FSW led to stronger hardening capacity and higher strain hardening exponent and rate due to the enhanced dislocation storage capacity associated with the microstructural change after FSW. The fracture surface of the FSWed joint was mainly characterized by dimples and tearing ridges along with micropores. © (2011) Trans Tech Publications, Switzerland.


Xu W.F.,Northwestern Polytechnical University | Liu J.H.,Northwestern Polytechnical University | Chen D.L.,Ryerson University | Luan G.H.,Beijing FSW Technology Ltd Company | Yao J.S.,Shanghai Aerospace Equipments Manufacturer
Materials Science and Engineering A | Year: 2012

Microstructures, tensile properties and strain hardening behavior of a friction stir welded (FSWed) thick AA2219 aluminum alloy under optimized welding parameters and varying cooling conditions (air cooling and water cooling) were investigated with three slices (top, middle and bottom) through the plate thickness. While the yield strength was lower in the FSWed joints than in the base metal, the ultimate tensile strength of the FSWed joints with water cooling reached nearly that of the base metal. In particular, FSW resulted in a significant improvement in the ductility of the alloy due to the presence of recrystallized fine grains with fragmented and uniformly dispersed second-phase particles in the weld nugget zone. Water cooling resulted in both higher strength and ductility, but lower strain hardening capacity than that with air cooling during FSW. Compared with the middle and bottom slices, the top slice had a higher strength, but lower ductility and strain hardening capacity. While stages III and IV hardening occurred after yielding in both base metal and FSWed samples, the FSW led to higher hardening capacity and strain hardening rate and exponent mainly in the middle and bottom slices. The fracture surfaces after FSW exhibited more obvious ductile fracture characteristics with dimples and tearing ridges along with micropores. © 2012.


Fu R.,State Key Laboratory of Metastable Materials Science and Technology | Fu R.,Yanshan University | Xu H.,Yanshan University | Luan G.,Beijing FSW Technology Ltd Company | And 4 more authors.
Materials Characterization | Year: 2012

We characterized the microstructures on the top surface of friction-stir welding (FSW) joints of AA2524 aluminum alloys with Alclad. Types, distributions, dissolution and precipitation behaviors of the precipitates in different regions of the joints were investigated. The results show that the as-polished surface microstructures under the shoulder of the FSW tool exhibited "arc strip" feature. The Alclad on the outer surface of the plate was destroyed during FSW, and the residual Alclad was enriched in the retreating side of the FSW joint. The main precipitates in the FSW joint were composed of Guinier-Preston (GP) zones and θ′ (Al 2Cu), S′ (Al 2CuMg) and Fe-containing phases. In the heat-affected and thermal-mechanical-affected zones, coarsening occurred in some S′ phases. In the GP zone, some S″ phases were transformed into stable S′ or S phases. In the nugget zone, the density of the precipitates decreased due to the dissolution of some S′ or S phases back into the matrix during the weld-heating period, whereas during the weld-cooling period, the refined and dispersed unstable GP zones or S″ phases reprecipitated. © 2012 Elsevier Inc. All rights reserved.


Kang J.,Yanshan University | Fu R.-d.,State Key Laboratory of Metastable Materials Science and Technology | Fu R.-d.,Yanshan University | Luan G.-h.,Beijing FSW Technology Ltd Company | And 2 more authors.
Corrosion Science | Year: 2010

The surface corrosion behavior of an AA2024-T3 aluminium alloy sheet after friction stir welding was investigated by using an "in-situ observation" method. SEM observations showed that the density and degree of the pitting corrosion in the shoulder active zone were slightly larger compared to the other regions on the top surface. The origins of the pitting corrosion were in the regions between the S phase particles and the adjacent aluminium base. The effect of Al-Cu-Fe-Mn-(Si) intermetallic compounds on the pitting corrosion was attributed to their high self-corrosion potential which induced the anodic dissolution of the surrounding aluminium matrix. © 2009 Elsevier Ltd. All rights reserved.

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