In dry storage,spent fuel is typically stored in casks constructed from neutron absorbing materials(NAMs).The(B_(4)C+Al_(2)O_(3))/Al composite,which incorporates in-situ amorphous Al_(2)O_(3)(am-Al_(2)O_(3))formed on ...In dry storage,spent fuel is typically stored in casks constructed from neutron absorbing materials(NAMs).The(B_(4)C+Al_(2)O_(3))/Al composite,which incorporates in-situ amorphous Al_(2)O_(3)(am-Al_(2)O_(3))formed on fine aluminum powder as a reinforcing phase,can serve as an integrated structural and functional NAM for dry storage applications.Welding is crucial in the fabrication of these casks.In this study,friction stir welding was performed on(B_(4)C+Al_(2)O_(3))/Al composite sheets at a welding speed of 50 mm/min and rotation rates ranging from 500 to 1000 r/min.The microstructure of the weld joints was analyzed,and the intrinsic relationship between fracture behavior and microstructure was elucidated.Results showed that defect-free joints were achieved at rotation rates of 500 and 750 r/min,while tunnel defects were observed at 1000 r/min.The ultimate tensile strength of the joint welded at 500 r/min was 205.7 MPa,with a strength efficiency of 82%.Microstructural analysis revealed that the grains within the nugget zones(NZs)coarsened and the Al_(2)O_(3)network was disrupted due to the welding thermo-mechanical effect,resulting in softening within the NZs.Fracture locations for all three joints were consistently observed at the NZ boundary on the advancing side(AS).Finite element simulations confirmed that cracks propagated along the NZ boundary on the AS,where stress concentration occurred during tensile testing.展开更多
3-mm-thick 5083Al-H19 rolled plates were friction stir welded(FSW) at tool rotation rates of 800 and200 rpm with and without additional water cooling. With decreasing the rotation rate and applying water cooling, soft...3-mm-thick 5083Al-H19 rolled plates were friction stir welded(FSW) at tool rotation rates of 800 and200 rpm with and without additional water cooling. With decreasing the rotation rate and applying water cooling, softening in the FSW joint was significantly reduced. At a low rotation rate of 200 rpm with additional water cooling, almost no obvious softening was observed in the FSW joint, and therefore a FSW5083Al-H19 joint with nearly equal strength to the base material(BM) was obtained. Furthermore, the grains in the nugget zone were considerably refined with reducing the heat input and ultrafine equiaxed grains of about 800 nm were obtained in the lowest heat input condition. This work provides an effective method to achieve high property FSW joints of precipitate-hardened and work-hardened Al alloys.展开更多
基金support of the National Natural Science Foundation of China(Grant Nos.52171056 and 52203385)the Joint Funds of the National Natural Science Foundation of China(Grant Nos.U2341255 and U22A20114)+1 种基金the Young Elite Scientists Sponsorship Program by CAST(Grant No.YESS20220225)the IMR Innovation Fund(Grant No.2021-ZD02).
文摘In dry storage,spent fuel is typically stored in casks constructed from neutron absorbing materials(NAMs).The(B_(4)C+Al_(2)O_(3))/Al composite,which incorporates in-situ amorphous Al_(2)O_(3)(am-Al_(2)O_(3))formed on fine aluminum powder as a reinforcing phase,can serve as an integrated structural and functional NAM for dry storage applications.Welding is crucial in the fabrication of these casks.In this study,friction stir welding was performed on(B_(4)C+Al_(2)O_(3))/Al composite sheets at a welding speed of 50 mm/min and rotation rates ranging from 500 to 1000 r/min.The microstructure of the weld joints was analyzed,and the intrinsic relationship between fracture behavior and microstructure was elucidated.Results showed that defect-free joints were achieved at rotation rates of 500 and 750 r/min,while tunnel defects were observed at 1000 r/min.The ultimate tensile strength of the joint welded at 500 r/min was 205.7 MPa,with a strength efficiency of 82%.Microstructural analysis revealed that the grains within the nugget zones(NZs)coarsened and the Al_(2)O_(3)network was disrupted due to the welding thermo-mechanical effect,resulting in softening within the NZs.Fracture locations for all three joints were consistently observed at the NZ boundary on the advancing side(AS).Finite element simulations confirmed that cracks propagated along the NZ boundary on the AS,where stress concentration occurred during tensile testing.
基金supported by the National Natural Science Foundation of China under grant Nos. 51301178 and 51331008
文摘3-mm-thick 5083Al-H19 rolled plates were friction stir welded(FSW) at tool rotation rates of 800 and200 rpm with and without additional water cooling. With decreasing the rotation rate and applying water cooling, softening in the FSW joint was significantly reduced. At a low rotation rate of 200 rpm with additional water cooling, almost no obvious softening was observed in the FSW joint, and therefore a FSW5083Al-H19 joint with nearly equal strength to the base material(BM) was obtained. Furthermore, the grains in the nugget zone were considerably refined with reducing the heat input and ultrafine equiaxed grains of about 800 nm were obtained in the lowest heat input condition. This work provides an effective method to achieve high property FSW joints of precipitate-hardened and work-hardened Al alloys.
