The effects of the inter-annealing process on the microstructure,plane stress fracture toughness,and tensile properties of an AA7075 cladding sheet were investigated using optical microscopy,scanning electron microsco...The effects of the inter-annealing process on the microstructure,plane stress fracture toughness,and tensile properties of an AA7075 cladding sheet were investigated using optical microscopy,scanning electron microscopy,electron backscattered diffraction,transmission electron microscopy,and mechanical property tests.The results indicate that the plane stress fracture toughness of AA7075-T6 cladding sheet can be greatly improved.The plane stress fracture toughness for the longitudinal-transverse(L-T)and transverse-longitudinal(T-L)directions were 117.7 and 94.8 MPa·m^(1/2),respectively,after intermediate annealing at 380°C.This represents an increase of 23.9 MPa·m^(1/2)in the L-T direction and 22.6 MPa·m^(1/2) in the T-L direction compared with the AA7075-T6 cladding sheet without intermediate annealing.Moreover,the tensile strength remains similar under different conditions.Microstructure analysis indicates that intermediate annealing before heat treatment can result in long sub-grains,few recrystallized grain boundaries,and small size precipitates in AA7075-T6 cladding sheets.展开更多
Bulge is a defect that causes geometrical inaccuracy and premature failure in the innovative incremental sheet forming (ISF) process. This study has two-fold objectives:(1) knowing the bulging behavior of a Cu clad tr...Bulge is a defect that causes geometrical inaccuracy and premature failure in the innovative incremental sheet forming (ISF) process. This study has two-fold objectives:(1) knowing the bulging behavior of a Cu clad tri-layered steel sheet as a function of forming conditions, and (2) analyzing the bending effect on bulging in an attempt to identify the associated mechanism. A series of ISF tests and bending analysis are performed to realize these objectives. From the cause-effect analysis, it is found that bulge formation in the layered sheet is sensitive to forming conditions in a way that bulging can be minimized utilizing annealed material and performing ISF with larger tool diameter and step size. The bending under tension analysis reveals that the formation of bulge is an outgrowth of bending moment that the forming tool applies on the sheet during ISF. Furthermore, the magnitude of bending moment depending upon the forming conditions varies from 0.046 to 10.24 N·m/m and causes a corresponding change in the mean bulge height from 0.07 to 0.91 mm. The bending moment governs bulging in layered sheet through a linear law. These findings lead to a conclusion that the bulge defect can be overcome by controlling the bending moment and the formula proposed can be helpful in this regards.展开更多
The law of microstructure evolution and mechanical properties of hot roll bonded Cu/Mo/Cu clad sheets were systematically investigated and the theoretical prediction model of the coefficient of thermal expansion(CTE)o...The law of microstructure evolution and mechanical properties of hot roll bonded Cu/Mo/Cu clad sheets were systematically investigated and the theoretical prediction model of the coefficient of thermal expansion(CTE)of Cu/Mo/Cu clad sheets was established successfully.The results show that the deformation of Cu and Mo layers was gradually coherent with an increase in rolling reduction and temperature and excellent interface bonding was achieved under the condition of a large rolling reduction.The development of the microstructure and texture through the thickness of Cu and Mo layers was inhomogeneous.This phenomenon can be attributed to the friction between the roller and sheet surface and the uncoordinated deformation between Cu and Mo.The tensile strength of the clad sheets increased with increasing rolling reduction and the elongation was gradually decreased.The CTE of Cu/Mo/Cu clad sheets was related to the volume fraction of Mo.The finite element method can simulate the deformation and stress distribution during the thermal expansion process.The simulation result indicates that the terminal face of the clad sheets was sunken inward.展开更多
Electromagnetic field is an available online method to increase bonding strength of clad sheet manufactured by horizontal twin-roll casting （HTRC）. In this paper, an electric current pulse （ECP） and a complex fie...Electromagnetic field is an available online method to increase bonding strength of clad sheet manufactured by horizontal twin-roll casting （HTRC）. In this paper, an electric current pulse （ECP） and a complex field （static magnetic field （SMF） together with ECP） are exerted during HTRC of steel/aluminum clad sheet. The produced clad sheet has good appearance, and no visible defects exist at the bonding interface. The inter-diffusion zone at Fe/A1 interface in ECP and SMF＋ECP sheets is 3 and 4 μm, respectively, and the latter increases slightly compared with that in non-field sheet. The average peel strengths （APS） of ECP and SMF＋ECP sheet are 14 and 21 N/mm, respectively, which increase by 2 and 9 N/mm compared with 12 N/mm of non-field sheet. The APS increment in SMF＋ECP sheet is resulted from the increment of interface bonding spots and the enhancement of inter-diffusion zone width.展开更多
Bonding together two or more materials with different properties to obtain a new material with better properties has been a long-standing concept and practice in human history. One example that is relevant all around ...Bonding together two or more materials with different properties to obtain a new material with better properties has been a long-standing concept and practice in human history. One example that is relevant all around the world is making a sharp and break-resistant knife with a hard steel edge and tough steel on the back of the blade. Until 1868, the volume of composite steels manufactured was quite small and productivity was low.展开更多
基金the National Key R&D Program of China(Nos.2023YFB3710401,2022YFB3504401)the National Natural Science Foundation of China(Nos.52271094,U1708251)+1 种基金the Key Research and Development Program of Liaoning,China(No.2020JH2/10700003)Qingyuan City Science and Technology Plan Project(No.2023YFJH003),China.
文摘The effects of the inter-annealing process on the microstructure,plane stress fracture toughness,and tensile properties of an AA7075 cladding sheet were investigated using optical microscopy,scanning electron microscopy,electron backscattered diffraction,transmission electron microscopy,and mechanical property tests.The results indicate that the plane stress fracture toughness of AA7075-T6 cladding sheet can be greatly improved.The plane stress fracture toughness for the longitudinal-transverse(L-T)and transverse-longitudinal(T-L)directions were 117.7 and 94.8 MPa·m^(1/2),respectively,after intermediate annealing at 380°C.This represents an increase of 23.9 MPa·m^(1/2)in the L-T direction and 22.6 MPa·m^(1/2) in the T-L direction compared with the AA7075-T6 cladding sheet without intermediate annealing.Moreover,the tensile strength remains similar under different conditions.Microstructure analysis indicates that intermediate annealing before heat treatment can result in long sub-grains,few recrystallized grain boundaries,and small size precipitates in AA7075-T6 cladding sheets.
基金the financial help and technical support that King Abdulaziz University provided for this research work
文摘Bulge is a defect that causes geometrical inaccuracy and premature failure in the innovative incremental sheet forming (ISF) process. This study has two-fold objectives:(1) knowing the bulging behavior of a Cu clad tri-layered steel sheet as a function of forming conditions, and (2) analyzing the bending effect on bulging in an attempt to identify the associated mechanism. A series of ISF tests and bending analysis are performed to realize these objectives. From the cause-effect analysis, it is found that bulge formation in the layered sheet is sensitive to forming conditions in a way that bulging can be minimized utilizing annealed material and performing ISF with larger tool diameter and step size. The bending under tension analysis reveals that the formation of bulge is an outgrowth of bending moment that the forming tool applies on the sheet during ISF. Furthermore, the magnitude of bending moment depending upon the forming conditions varies from 0.046 to 10.24 N·m/m and causes a corresponding change in the mean bulge height from 0.07 to 0.91 mm. The bending moment governs bulging in layered sheet through a linear law. These findings lead to a conclusion that the bulge defect can be overcome by controlling the bending moment and the formula proposed can be helpful in this regards.
基金financial supports from the National Natural Science Foundation of China (No.51421001)the Fundamental Research Funds for the Central Universities,China (Nos.2019CDQY CL001,2019CDCGCL204,2020CDJDPT001)the Research Project of State Key Laboratory of Vehicle NVH and Safety Technology,China (No.NVHSKL-201706)。
文摘The law of microstructure evolution and mechanical properties of hot roll bonded Cu/Mo/Cu clad sheets were systematically investigated and the theoretical prediction model of the coefficient of thermal expansion(CTE)of Cu/Mo/Cu clad sheets was established successfully.The results show that the deformation of Cu and Mo layers was gradually coherent with an increase in rolling reduction and temperature and excellent interface bonding was achieved under the condition of a large rolling reduction.The development of the microstructure and texture through the thickness of Cu and Mo layers was inhomogeneous.This phenomenon can be attributed to the friction between the roller and sheet surface and the uncoordinated deformation between Cu and Mo.The tensile strength of the clad sheets increased with increasing rolling reduction and the elongation was gradually decreased.The CTE of Cu/Mo/Cu clad sheets was related to the volume fraction of Mo.The finite element method can simulate the deformation and stress distribution during the thermal expansion process.The simulation result indicates that the terminal face of the clad sheets was sunken inward.
基金supported by the Industry-Academia-Research projects of Guangdong province, P. R. China (Grant Nos. 2014B090903012, 2013B090200008 and 2013B090600015)
文摘Electromagnetic field is an available online method to increase bonding strength of clad sheet manufactured by horizontal twin-roll casting （HTRC）. In this paper, an electric current pulse （ECP） and a complex field （static magnetic field （SMF） together with ECP） are exerted during HTRC of steel/aluminum clad sheet. The produced clad sheet has good appearance, and no visible defects exist at the bonding interface. The inter-diffusion zone at Fe/A1 interface in ECP and SMF＋ECP sheets is 3 and 4 μm, respectively, and the latter increases slightly compared with that in non-field sheet. The average peel strengths （APS） of ECP and SMF＋ECP sheet are 14 and 21 N/mm, respectively, which increase by 2 and 9 N/mm compared with 12 N/mm of non-field sheet. The APS increment in SMF＋ECP sheet is resulted from the increment of interface bonding spots and the enhancement of inter-diffusion zone width.
文摘Bonding together two or more materials with different properties to obtain a new material with better properties has been a long-standing concept and practice in human history. One example that is relevant all around the world is making a sharp and break-resistant knife with a hard steel edge and tough steel on the back of the blade. Until 1868, the volume of composite steels manufactured was quite small and productivity was low.
