To explore the complex thermal-mechanical-chemical behavior in the solid-liquid cast-roll bonding(SLCRB) of Cu/Al cladding strip, numerical simulations were conducted from both macro and micro scales. In macro-scale, ...To explore the complex thermal-mechanical-chemical behavior in the solid-liquid cast-roll bonding(SLCRB) of Cu/Al cladding strip, numerical simulations were conducted from both macro and micro scales. In macro-scale, with birth and death element method, a thermo-mechanical coupled finite element model(FEM) was set up to explore the temperature and contact pressure distribution at the Cu/Al bonding interface in the SLCRB process. Taking these macro-scale simulation results as boundary conditions, we simulated the atom diffusion law of the bonding interface by molecular dynamics(MD) in micro-scale. The results indicate that the temperature in Cu/Al bonding interface deceases from 700 to 320 ℃ from the entrance to the exit of caster, and the peak of contact pressure reaches up to 140 MPa. The interfacial diffusion thickness depends on temperature and rolling reduction, higher temperature results in larger thickness, and the rolling reduction below kiss point leads to significant elongation deformation of cladding strip which yields more newborn interface with fresh metal and make the diffusion layer thinner. The surface roughness of Cu strip was found to be benefit to atoms diffusion in the Cu/Al bonding interface. Meanwhile, combined with the SEM-EDS observation on the microstructure and composition in the bonding interface of the experimental samples acquired from the castrolling bite, it is revealed that the rolling reduction and severe elongation deformation in the solid-solid contact zone below kiss point guarantee the satisfactory metallurgical bonding with thin and smooth diffusion layer. The bonding mechanisms of reactive diffusion, mechanical interlocking and crack bonding are proved to coexist in the SLCRB process.展开更多
The 304 stainless steel strips were deposited one layer on carbon steel base metal by electroslag strip cladding (ESC) and submerged arc cladding (SAC), respectively. The solidification microstrueture of ESC metal...The 304 stainless steel strips were deposited one layer on carbon steel base metal by electroslag strip cladding (ESC) and submerged arc cladding (SAC), respectively. The solidification microstrueture of ESC metal was analyzed by the optical microscopy, scanning electron microscope and energy dispersive spectroscopy. The corrosion resistance studies of strip cladding metals were carried out in 10% oxalic acid electrolytic etching test. The results showed that the cladding metal obtained by ESC presented low content of C, high content of Cr and enough alloying element of Ni in the chemical composition. The transition zone of ESC with small width was almost parallel with the base metal, leading to a lower dilution. There are three types of solidification modes ( A→AF→FA ) occurred in the ESC metal due to the decrease of cooling rate and degree of dilution from the transition zone to the top of ESC metal. As a result, the microstructure of ESC metal exhibited mainly austenite with a small amount of ferrite, contributing to achievement of better corrosion resistance.展开更多
为了实现热连轧精轧机组负荷分配的在线优化设定,提出一种轧制力成比例负荷分配的新算法CLAD算法(change load ratio by adjusting draft).其要点是通过调整压下量的偏差来使当前轧制力与目标轧制力的偏差最小化.根据轧制力成比例原则...为了实现热连轧精轧机组负荷分配的在线优化设定,提出一种轧制力成比例负荷分配的新算法CLAD算法(change load ratio by adjusting draft).其要点是通过调整压下量的偏差来使当前轧制力与目标轧制力的偏差最小化.根据轧制力成比例原则建立非线性方程组,结合假设条件,将系数矩阵简化为对角阵,经数学推导给出了新算法的迭代公式和收敛条件.提出一种经验插值法确定初始值,使得负荷分配迭代计算能快速收敛.对宝钢典型轧制案例的模拟计算验证了新算法具有计算速度快、收敛性好等优点,可用于在线计算.展开更多
Taking advantage of the progress of roll-bonding technology, the integrity of the material technology, and the development of the production and examination facilities of all the main carbon steels, stainless steels a...Taking advantage of the progress of roll-bonding technology, the integrity of the material technology, and the development of the production and examination facilities of all the main carbon steels, stainless steels and specialty alloys in Baosteel, the cladded flat new products, which combined both properties of base material and clad material ,have been developed and produced in large quantities. The product categories includes heavy plates with high alloy content and homogeneous distribution in thickness and carbon steel plates cladded with all kinds of stainless steels ,nickel alloys ,and titanium alloys. The double-sided and single-sided cladding hot roiled strips and cold rolled sheets were also commercially produced. Due to the combined properties of both the cladding material and backing material, all products show obvious improvement in properties when compared with solid material. The comparability with the existing production process and equipment laid a very solid foundation for high productivity.展开更多
The effect of cold-rolling, by both a series of small passes and single-pass with different deformations as well as the subsequent annealing, on the interfacial structures and properties of A500(AlSn8Pb2Si2.5Cu0.8Cr...The effect of cold-rolling, by both a series of small passes and single-pass with different deformations as well as the subsequent annealing, on the interfacial structures and properties of A500(AlSn8Pb2Si2.5Cu0.8Cr0.2)/steel bimetal strip produced by liquid-solid roll cladding was investigated. Experimental results of the cold-rolling by a series of small passes show that the interfacial bonding strength increases slightly when the total deformation is less than 7.32% and then decreases gradually with the increase in deformation. Subsequent annealing has no effect on the interfacial structures and properties. The effect of cold-rolling by single-pass less than 33.2% deformation on the interfacial structures and properties is the same as that of multi-pass cold-rolling, whereas cold-rolling by single-pass more than 33.2% deformation followed by annealing at 350℃ for 2.5h can make the interfacial bonding strength increase to a great extent. Metallographic examination of the interface shows that there exist only transverse cracks within the interfacial layer and the clad strip does not split along the interface during cold-rolling if the thickness of interfacial layer is less than 45μm. The thick interfacial layer(>56μm), however, crumbles during cold-rolling, thus resulting in the splitting of the clad strip.展开更多
基金Funded by the General Program of National Natural Science Foundation of China(Nos.51474189 and 51674222)the Excellent Youth Foundation of Hebei Scientific Committee,China(No.E2018203446)the Scientific Research Foundation of the Higher Education Institutions of Hebei Province,China(No.QN2015214)
文摘To explore the complex thermal-mechanical-chemical behavior in the solid-liquid cast-roll bonding(SLCRB) of Cu/Al cladding strip, numerical simulations were conducted from both macro and micro scales. In macro-scale, with birth and death element method, a thermo-mechanical coupled finite element model(FEM) was set up to explore the temperature and contact pressure distribution at the Cu/Al bonding interface in the SLCRB process. Taking these macro-scale simulation results as boundary conditions, we simulated the atom diffusion law of the bonding interface by molecular dynamics(MD) in micro-scale. The results indicate that the temperature in Cu/Al bonding interface deceases from 700 to 320 ℃ from the entrance to the exit of caster, and the peak of contact pressure reaches up to 140 MPa. The interfacial diffusion thickness depends on temperature and rolling reduction, higher temperature results in larger thickness, and the rolling reduction below kiss point leads to significant elongation deformation of cladding strip which yields more newborn interface with fresh metal and make the diffusion layer thinner. The surface roughness of Cu strip was found to be benefit to atoms diffusion in the Cu/Al bonding interface. Meanwhile, combined with the SEM-EDS observation on the microstructure and composition in the bonding interface of the experimental samples acquired from the castrolling bite, it is revealed that the rolling reduction and severe elongation deformation in the solid-solid contact zone below kiss point guarantee the satisfactory metallurgical bonding with thin and smooth diffusion layer. The bonding mechanisms of reactive diffusion, mechanical interlocking and crack bonding are proved to coexist in the SLCRB process.
基金sponsored by National Natural Science Foundation of China(Grant No.51101050)Fundamental Research Funds for the Central Universities(Grant No.2015B22614)Natural Science Foundation of Jiangsu Province of China(Grant No.BK20141156)
文摘The 304 stainless steel strips were deposited one layer on carbon steel base metal by electroslag strip cladding (ESC) and submerged arc cladding (SAC), respectively. The solidification microstrueture of ESC metal was analyzed by the optical microscopy, scanning electron microscope and energy dispersive spectroscopy. The corrosion resistance studies of strip cladding metals were carried out in 10% oxalic acid electrolytic etching test. The results showed that the cladding metal obtained by ESC presented low content of C, high content of Cr and enough alloying element of Ni in the chemical composition. The transition zone of ESC with small width was almost parallel with the base metal, leading to a lower dilution. There are three types of solidification modes ( A→AF→FA ) occurred in the ESC metal due to the decrease of cooling rate and degree of dilution from the transition zone to the top of ESC metal. As a result, the microstructure of ESC metal exhibited mainly austenite with a small amount of ferrite, contributing to achievement of better corrosion resistance.
文摘为了实现热连轧精轧机组负荷分配的在线优化设定,提出一种轧制力成比例负荷分配的新算法CLAD算法(change load ratio by adjusting draft).其要点是通过调整压下量的偏差来使当前轧制力与目标轧制力的偏差最小化.根据轧制力成比例原则建立非线性方程组,结合假设条件,将系数矩阵简化为对角阵,经数学推导给出了新算法的迭代公式和收敛条件.提出一种经验插值法确定初始值,使得负荷分配迭代计算能快速收敛.对宝钢典型轧制案例的模拟计算验证了新算法具有计算速度快、收敛性好等优点,可用于在线计算.
文摘Taking advantage of the progress of roll-bonding technology, the integrity of the material technology, and the development of the production and examination facilities of all the main carbon steels, stainless steels and specialty alloys in Baosteel, the cladded flat new products, which combined both properties of base material and clad material ,have been developed and produced in large quantities. The product categories includes heavy plates with high alloy content and homogeneous distribution in thickness and carbon steel plates cladded with all kinds of stainless steels ,nickel alloys ,and titanium alloys. The double-sided and single-sided cladding hot roiled strips and cold rolled sheets were also commercially produced. Due to the combined properties of both the cladding material and backing material, all products show obvious improvement in properties when compared with solid material. The comparability with the existing production process and equipment laid a very solid foundation for high productivity.
基金Project(2002AA334060) supported by the National High-Tech Research and Development Programof China
文摘The effect of cold-rolling, by both a series of small passes and single-pass with different deformations as well as the subsequent annealing, on the interfacial structures and properties of A500(AlSn8Pb2Si2.5Cu0.8Cr0.2)/steel bimetal strip produced by liquid-solid roll cladding was investigated. Experimental results of the cold-rolling by a series of small passes show that the interfacial bonding strength increases slightly when the total deformation is less than 7.32% and then decreases gradually with the increase in deformation. Subsequent annealing has no effect on the interfacial structures and properties. The effect of cold-rolling by single-pass less than 33.2% deformation on the interfacial structures and properties is the same as that of multi-pass cold-rolling, whereas cold-rolling by single-pass more than 33.2% deformation followed by annealing at 350℃ for 2.5h can make the interfacial bonding strength increase to a great extent. Metallographic examination of the interface shows that there exist only transverse cracks within the interfacial layer and the clad strip does not split along the interface during cold-rolling if the thickness of interfacial layer is less than 45μm. The thick interfacial layer(>56μm), however, crumbles during cold-rolling, thus resulting in the splitting of the clad strip.