The method based on transient heat transfer model is adopted to simulate electro-slag remelting process. The calculated results of the model show that the process is in the quasi-steady state, and the shape of pool re...The method based on transient heat transfer model is adopted to simulate electro-slag remelting process. The calculated results of the model show that the process is in the quasi-steady state, and the shape of pool remains unchanged when the height of ingot is approximately 2.5-3 times the thickness of slab ingot. The change in the shape of pool is found to be strongly dependent on the pattern of melting rate, and hence, the power input; the depth of the molten pool increases with the increase in melting speed. It is concluded that a transient heat transfer model has to be used to obtain reliable input information for the entire, operatina time.展开更多
Shrinkage porosity defect is often found in an air cooled jumbo steel ingot, which will influence the quality of the final rolled plates. In practical production, some rolled plates are frequently rejected due to the ...Shrinkage porosity defect is often found in an air cooled jumbo steel ingot, which will influence the quality of the final rolled plates. In practical production, some rolled plates are frequently rejected due to the serious shrinkage porosity of the ingot. To improve the quality of the ingot, a new cooling method, gradient cooling process （in which the upper part of the ingot is air cooled and the lower part is spray cooled） was put forward in this study. The solidification behaviors for a 60 t jumbo slab ingot under gradient cooling condition were simulated using the ProCast software, and the results were compared with those of an ingot by air cooling condition. The solidifying tendency, temperature field and distribution of shrinkage porosities in the ingot under different cooling conditions were analyzed. Simulation results show that under gradient cooling condition the solidification of the slab ingot progresses in an upward manner along the vertical z axis and in a centripetal manner along the horizontal x and y axes. Gradient cooling can efficiently reduce shrinkage porosity of the jumbo slab ingot by optimizing the solidification sequence, and making the position of shrinkage porosity move from near the middle height of the ingot （under air cooling condition） towards the head of the ingot; and the secondary shrinkage is eliminated. In addition, the solidification time of the ingot under gradient cooling is 7.3 h in this simulation, which is 2.7 h faster than that under air cooling. A 60 t jumbo slab ingot was successfully produced under gradient cooling condition. The ingot was rolled to a plate with a thickness of 100 mm and length of 18,000 mm, and ultrasonic flaw detection was performed. Some porosity was found along the axis of the plate at 4,900 position of the defect is moved towards the head with the simulated result. - 6,000 mm from the head of the plate, indicating that the of the ingot. This distribution trend of the defect is consistent展开更多
The slag pool is a complex system which gathers electromagnetic field,thermal field and flow field in the process of electroslag remelting(ESR)for production of large slab ingots.In this manuscript,mathematic foundati...The slag pool is a complex system which gathers electromagnetic field,thermal field and flow field in the process of electroslag remelting(ESR)for production of large slab ingots.In this manuscript,mathematic foundation and boundary conditions of the numerical simulation for thermal field in the ESR process of large slab ingots were analyzed, and mathematic model of heat generation in the slag pool and the solidification in the metal molten pool were founded by using the finite element software ANSYS.According to the simulation results,it can be found that the temperature distribution in the process of ESR for production of large slab ingots with double electrode series is different from that in the electroslag furnace with a single electrode.The region of the biggest current density and the highest temperature in the electroslag furnace with a single electrode is below the electrode,while the same region in the process of ESR with the double electrode series for production of large slab ingots locates between the two electrodes.The depth of the metal pool and the temperature of the slag bath simulated by mathematical model were close to the measured value in the experimental process,which verifies the reliability of the simulation method and the model,and it will provide a theoretical basis for the quality control of large slab ingots in the process of ESR.展开更多
文摘The method based on transient heat transfer model is adopted to simulate electro-slag remelting process. The calculated results of the model show that the process is in the quasi-steady state, and the shape of pool remains unchanged when the height of ingot is approximately 2.5-3 times the thickness of slab ingot. The change in the shape of pool is found to be strongly dependent on the pattern of melting rate, and hence, the power input; the depth of the molten pool increases with the increase in melting speed. It is concluded that a transient heat transfer model has to be used to obtain reliable input information for the entire, operatina time.
基金supported by the Science and Technology Projects of Ministry of Education of P. R. China (The study on heat conducting and initial solidification shell of jumbo slab ingot under gradient cooling, Grant No. 20112120120003)
文摘Shrinkage porosity defect is often found in an air cooled jumbo steel ingot, which will influence the quality of the final rolled plates. In practical production, some rolled plates are frequently rejected due to the serious shrinkage porosity of the ingot. To improve the quality of the ingot, a new cooling method, gradient cooling process （in which the upper part of the ingot is air cooled and the lower part is spray cooled） was put forward in this study. The solidification behaviors for a 60 t jumbo slab ingot under gradient cooling condition were simulated using the ProCast software, and the results were compared with those of an ingot by air cooling condition. The solidifying tendency, temperature field and distribution of shrinkage porosities in the ingot under different cooling conditions were analyzed. Simulation results show that under gradient cooling condition the solidification of the slab ingot progresses in an upward manner along the vertical z axis and in a centripetal manner along the horizontal x and y axes. Gradient cooling can efficiently reduce shrinkage porosity of the jumbo slab ingot by optimizing the solidification sequence, and making the position of shrinkage porosity move from near the middle height of the ingot （under air cooling condition） towards the head of the ingot; and the secondary shrinkage is eliminated. In addition, the solidification time of the ingot under gradient cooling is 7.3 h in this simulation, which is 2.7 h faster than that under air cooling. A 60 t jumbo slab ingot was successfully produced under gradient cooling condition. The ingot was rolled to a plate with a thickness of 100 mm and length of 18,000 mm, and ultrasonic flaw detection was performed. Some porosity was found along the axis of the plate at 4,900 position of the defect is moved towards the head with the simulated result. - 6,000 mm from the head of the plate, indicating that the of the ingot. This distribution trend of the defect is consistent
基金Item Sponsored by Central University of basic scientific research expenses in the National Natural Science Foundation of China Youth Project (51104038) Basic scientific research expenses of young teachers'scientific research project (N100302006)
文摘The slag pool is a complex system which gathers electromagnetic field,thermal field and flow field in the process of electroslag remelting(ESR)for production of large slab ingots.In this manuscript,mathematic foundation and boundary conditions of the numerical simulation for thermal field in the ESR process of large slab ingots were analyzed, and mathematic model of heat generation in the slag pool and the solidification in the metal molten pool were founded by using the finite element software ANSYS.According to the simulation results,it can be found that the temperature distribution in the process of ESR for production of large slab ingots with double electrode series is different from that in the electroslag furnace with a single electrode.The region of the biggest current density and the highest temperature in the electroslag furnace with a single electrode is below the electrode,while the same region in the process of ESR with the double electrode series for production of large slab ingots locates between the two electrodes.The depth of the metal pool and the temperature of the slag bath simulated by mathematical model were close to the measured value in the experimental process,which verifies the reliability of the simulation method and the model,and it will provide a theoretical basis for the quality control of large slab ingots in the process of ESR.
