The influences of the dissimilarity in the roll speeds on the microstructure, texture and mechanical properties of 7075 aluminum plates produced via combined continuous casting and rolling(CCCR) process were investiga...The influences of the dissimilarity in the roll speeds on the microstructure, texture and mechanical properties of 7075 aluminum plates produced via combined continuous casting and rolling(CCCR) process were investigated. Several experiments were conducted with three different upper/lower roll rotational speed ratios(ω/ω0, ω is the upper roll rotational speed and ω0 is the lower roll rotational speed), namely 1:1, 1:1.2 and 1:1.4. It was found that the greatest dissimilarity in the roll speed(ω/ω0=1:1.4) improved the yield strength and ultimate tensile strength of 7075 Al plate in the rolling direction by 41.5% and 21.9%, respectively. Moreover, at a roll speed ratio of ω/ω0=1:1.4, the average grain size was decreased by 36% whereas the mean hardness of the transverse cross-section of the finally rolled plate was increased by about 9.2%. Texture studies also revealed that the more the difference in the roll speeds was, the greater the isotropy and the hardness of the final product were. Nevertheless, conducting CCCR operation with different roll speeds resulted in about 6% reduction in the elongation of the deformed plate.展开更多
A modified horizontal continuous casting process under the electromagnetic field was proposed for preparing AA3003/ AA4045 clad composite hollow billets. To investigate the effect of electromagnetic field on this proc...A modified horizontal continuous casting process under the electromagnetic field was proposed for preparing AA3003/ AA4045 clad composite hollow billets. To investigate the effect of electromagnetic field on this process, a comprehensive three-dimensional model was developed. Two cases with and without electromagnetic field were compared using the simulations. When rotating electromagnetic stirring is applied, the flow pattern of fluid melt is greatly modified; the mushy zone becomes much wider, the temperature profile becomes more uniform, and the solid fraction decreases for both the external and internal alloy melt layers. These modifications are beneficial for the formation of a bimetal interface and fine and uniform grain structure of the clad composite hollow billet. Experiments conducted using the same electrical and casting parameters as the simulations verify that under the electromagnetic field the microstructure of the clad composite hollow billet becomes fine and the diffusion of the elements at the interface is promoted.展开更多
Columnar-grained QSn6. 5-0. 1 alloy slabs with a width of 70 mm and thickness of 10 mm were fabricated by heating-cooling combined mold（ HCCM） horizontal continuous casting. The effects of process parameters on soli...Columnar-grained QSn6. 5-0. 1 alloy slabs with a width of 70 mm and thickness of 10 mm were fabricated by heating-cooling combined mold（ HCCM） horizontal continuous casting. The effects of process parameters on solidification microstructure,surface quality,composition segregation and mechanical properties were studied. The results showed that the slabs with good surface quality,excellent mechanical properties and no obvious segregation could be prepared at the melt casting temperature of 1 250 ℃,the heating-mold temperature of 1 150- 1 200℃,the cooling water flow rate of 600 L / h and the casting speed of 20- 80 mm / min. The slabs had the yield strength of 124- 155 MPa,the elongation rate of 46. 6%- 56. 3% and the surface roughness of 0. 22- 0. 55μm,which enabled them to be directly processed without subsequent milling surface. The ratio of Sn content in the surface to that in the core was 0. 83- 1. 10,with an average value close to 1. 0,and not obviously influenced by process parameters. When the casting speed increased from 20 to 80 mm / min,the grain size changed little if the other process parameters were the same. When the heating-mold temperature increased from 1 150 to 1 200℃,the grain size was obviously refined and became more uniform if the casting speed was the same. Within the range of the casting speed at which the columnar grain structure could be obtained,the columnar grain size was mainly influenced by the heating-mold temperature.展开更多
A new composite material consisting of lxxx aluminum alloy and 7xxx aluminum alloy was produced by semi-continuous casting. Macrostructure, microstructure, composition distribution and hardness distribution of composi...A new composite material consisting of lxxx aluminum alloy and 7xxx aluminum alloy was produced by semi-continuous casting. Macrostructure, microstructure, composition distribution and hardness distribution of composite interface were analyzed. Macrostructure shows that composite interface is planar and clean with little evidence of porosity; microstructure shows that composite interface is a kind of metallurgical bonding; composition and hardness distributions have a good corresponding relationship. At the same time, the mechanical property of composite interface was measured, the tensile strength is 71 MPa, the shearing strength is 62 MPa and the bending strength is 142.5 MPa, which can also show that composite interface is a kind of metallurgical bonding. Temperature distribution of composite interface was obtained by measuring temperatures near composite interface in lxxx aluminum alloy.展开更多
文摘The influences of the dissimilarity in the roll speeds on the microstructure, texture and mechanical properties of 7075 aluminum plates produced via combined continuous casting and rolling(CCCR) process were investigated. Several experiments were conducted with three different upper/lower roll rotational speed ratios(ω/ω0, ω is the upper roll rotational speed and ω0 is the lower roll rotational speed), namely 1:1, 1:1.2 and 1:1.4. It was found that the greatest dissimilarity in the roll speed(ω/ω0=1:1.4) improved the yield strength and ultimate tensile strength of 7075 Al plate in the rolling direction by 41.5% and 21.9%, respectively. Moreover, at a roll speed ratio of ω/ω0=1:1.4, the average grain size was decreased by 36% whereas the mean hardness of the transverse cross-section of the finally rolled plate was increased by about 9.2%. Texture studies also revealed that the more the difference in the roll speeds was, the greater the isotropy and the hardness of the final product were. Nevertheless, conducting CCCR operation with different roll speeds resulted in about 6% reduction in the elongation of the deformed plate.
基金Projects(51274054,U1332115,51271042,51375070,51401044)supported by the National Natural Science Foundation of ChinaProject(313011)supported by the Key Grant Project of Ministry of Education of China+4 种基金Project(2013A16GX110)supported by the Science and Technology Planning Project of Dalian,ChinaProject(2014M551075)supported by the China Postdoctoral Science FoundationProject supported by the Fundamental Research Funds for the Central Universities,China
文摘A modified horizontal continuous casting process under the electromagnetic field was proposed for preparing AA3003/ AA4045 clad composite hollow billets. To investigate the effect of electromagnetic field on this process, a comprehensive three-dimensional model was developed. Two cases with and without electromagnetic field were compared using the simulations. When rotating electromagnetic stirring is applied, the flow pattern of fluid melt is greatly modified; the mushy zone becomes much wider, the temperature profile becomes more uniform, and the solid fraction decreases for both the external and internal alloy melt layers. These modifications are beneficial for the formation of a bimetal interface and fine and uniform grain structure of the clad composite hollow billet. Experiments conducted using the same electrical and casting parameters as the simulations verify that under the electromagnetic field the microstructure of the clad composite hollow billet becomes fine and the diffusion of the elements at the interface is promoted.
基金financial support from the National Key Technology Support Program of China(No.2011BAE23B03 )the National Natural Science Foundation of China(51504023)the China Scholarship Council Project(No.201506465055)
文摘Columnar-grained QSn6. 5-0. 1 alloy slabs with a width of 70 mm and thickness of 10 mm were fabricated by heating-cooling combined mold（ HCCM） horizontal continuous casting. The effects of process parameters on solidification microstructure,surface quality,composition segregation and mechanical properties were studied. The results showed that the slabs with good surface quality,excellent mechanical properties and no obvious segregation could be prepared at the melt casting temperature of 1 250 ℃,the heating-mold temperature of 1 150- 1 200℃,the cooling water flow rate of 600 L / h and the casting speed of 20- 80 mm / min. The slabs had the yield strength of 124- 155 MPa,the elongation rate of 46. 6%- 56. 3% and the surface roughness of 0. 22- 0. 55μm,which enabled them to be directly processed without subsequent milling surface. The ratio of Sn content in the surface to that in the core was 0. 83- 1. 10,with an average value close to 1. 0,and not obviously influenced by process parameters. When the casting speed increased from 20 to 80 mm / min,the grain size changed little if the other process parameters were the same. When the heating-mold temperature increased from 1 150 to 1 200℃,the grain size was obviously refined and became more uniform if the casting speed was the same. Within the range of the casting speed at which the columnar grain structure could be obtained,the columnar grain size was mainly influenced by the heating-mold temperature.
基金supported by Major State Basic Research Project of China (GrantNo.2005CB623707)
文摘A new composite material consisting of lxxx aluminum alloy and 7xxx aluminum alloy was produced by semi-continuous casting. Macrostructure, microstructure, composition distribution and hardness distribution of composite interface were analyzed. Macrostructure shows that composite interface is planar and clean with little evidence of porosity; microstructure shows that composite interface is a kind of metallurgical bonding; composition and hardness distributions have a good corresponding relationship. At the same time, the mechanical property of composite interface was measured, the tensile strength is 71 MPa, the shearing strength is 62 MPa and the bending strength is 142.5 MPa, which can also show that composite interface is a kind of metallurgical bonding. Temperature distribution of composite interface was obtained by measuring temperatures near composite interface in lxxx aluminum alloy.
