At the late stage of continuous casting（CC）ladle teeming,sink vortex can suck the liquid slag into tundish,and cause negative influences on the cleanliness of molten steel.To address this issue,a twophase fluid mech...At the late stage of continuous casting（CC）ladle teeming,sink vortex can suck the liquid slag into tundish,and cause negative influences on the cleanliness of molten steel.To address this issue,a twophase fluid mechanical modeling method for ladle teeming was proposed.Firstly,a dynamic model for vortex suction process was built,and the profiles of vortex flow field were acquired.Then,based on the level set method（LSM）,a two-phase 3Dinterface coupling model for slag entrapment was built.Finally,in combination with high-order essentially non-oscillatory（ENO）and total variation diminishing（TVD）methods,a LSM-based numerical solution method was proposed to obtain the 3Dcoupling evolution regularities in vortex suction process.Numerical results show that the vortex with higher kinetic energy can form an expanded sandglass-shape region with larger slag fraction and lower rotating velocity;there is a pressure oscillation phenomenon at the vortex penetration state,which is caused by the energy shock of two-phase vortex penetration coupling.展开更多
Two kinds of argon shroud protection devices with two different basic structures were designed and investigated. Industrial experiments and numerical simulations were used to examine the protection effect, and the mec...Two kinds of argon shroud protection devices with two different basic structures were designed and investigated. Industrial experiments and numerical simulations were used to examine the protection effect, and the mechanism of air entrapment during the casting of steel ingots was analyzed. The influence of the structure of the argon shroud protection device on the protection effect was investigated. An argon shroud protection device mounted to the nozzle holder on the bottom of the ladle does not provide a good protection effect because air can easily flow into the teeming system and cause reoxidation of molten steel during teeming. By contrast, an argon shroud protection device seated on the top of the central trumpet provides an excellent protection effect, where air has little chance of flowing into the teeming system during casting. The feasibilities of the argon shroud protection devices are discussed.展开更多
Slag carry-over during the draining of molten steel from a teeming ladle is numerically studied here. Two-phase isothermal transient 3D Computational Fluid Dynamics simulations were employed to simulate the draining p...Slag carry-over during the draining of molten steel from a teeming ladle is numerically studied here. Two-phase isothermal transient 3D Computational Fluid Dynamics simulations were employed to simulate the draining process. Two nozzle diameters, two nozzle positions and three slag heights were considered. From mass balances, the slag carry-over in terms of mass flow rate was obtained for each of the above variables. Besides, the draining times of the teeming ladle were estimated from theoretical considerations and CDF simulations, and compared.展开更多
Steel teeming time is a very important parameter in the new slide gate system with electromagnetic induction （called electromagnetic steel teeming system）, and how to shorten this time is a key to realize applicatio...Steel teeming time is a very important parameter in the new slide gate system with electromagnetic induction （called electromagnetic steel teeming system）, and how to shorten this time is a key to realize application of the new system in continuous casting. The effects of power parameters, coil position, nozzle material and other factors on the steel teeming time were investigated by a self-designed electromagnetic steel teeming system in detail. The experimental results show that the relationship between power and steel teeming time is nonlinear. The coil position has great in- fluence on steel teeming time. And the upper nozzle with high permeability can reduce the teeming time. In addition, the steel teeming time becomes minimum when the size of the spherical cast iron particles is 2.0 ram. This research can provide technical references for the industrial application of the new electromagnetic steel teeming system.展开更多
An innovative process of clad teeming was proposed to prepare slab ingot,which featured a built-in cold core to inhibit solidification defects.A 20-kg clad ingot was prepared in the experiment,using a volume ratio of ...An innovative process of clad teeming was proposed to prepare slab ingot,which featured a built-in cold core to inhibit solidification defects.A 20-kg clad ingot was prepared in the experiment,using a volume ratio of solid core to molten steel of 1:13 and a preheating temperature of cold core of 573 K.Solidification microstructures of the clad ingot were analyzed by comparing with a reference ingot without cold core.Interfacial morphologies and mechanical properties of the clad ingot were studied before and after hot rolling.The effect of cold core on heat transfer and nucleation during the solidification in clad ingot was analyzed.Results show that the solidification microstructures in the clad ingot are refined and homogenized obviously.The grain size in the center of the reference ingot is 2–3 times greater than that of clad ingot,and there is almost no columnar grain in the clad ingot.The interfacial shear strength reaches 318 MPa,which shows excellent metallurgical bonding at the interface of cold core and molten steel.Tiny defects at the interface are eliminated,and interfacial shear strength reaches 426 MPa after hot rolling with a 68.4%total reduction ratio.The experiment and analysis of this process are expected to provide a new idea to prepare large ingots with refinement and homogeneity at a low cost.展开更多
基金supported by NSFC-Zhejiang Joint Fund for the Integration of Industrialization and Informatization(U1509212)National Natural Science Foundation of China(51375446)Zhejiang Provincial Natural Science Foundation for Distinguished Young Scientists(LR16E050001)
文摘At the late stage of continuous casting（CC）ladle teeming,sink vortex can suck the liquid slag into tundish,and cause negative influences on the cleanliness of molten steel.To address this issue,a twophase fluid mechanical modeling method for ladle teeming was proposed.Firstly,a dynamic model for vortex suction process was built,and the profiles of vortex flow field were acquired.Then,based on the level set method（LSM）,a two-phase 3Dinterface coupling model for slag entrapment was built.Finally,in combination with high-order essentially non-oscillatory（ENO）and total variation diminishing（TVD）methods,a LSM-based numerical solution method was proposed to obtain the 3Dcoupling evolution regularities in vortex suction process.Numerical results show that the vortex with higher kinetic energy can form an expanded sandglass-shape region with larger slag fraction and lower rotating velocity;there is a pressure oscillation phenomenon at the vortex penetration state,which is caused by the energy shock of two-phase vortex penetration coupling.
基金supported by the National Natural Science Foundation of China(Grant No.51404018)the State Key Laboratory of Advanced Metallurgy Foundation(No.41614014)
文摘Two kinds of argon shroud protection devices with two different basic structures were designed and investigated. Industrial experiments and numerical simulations were used to examine the protection effect, and the mechanism of air entrapment during the casting of steel ingots was analyzed. The influence of the structure of the argon shroud protection device on the protection effect was investigated. An argon shroud protection device mounted to the nozzle holder on the bottom of the ladle does not provide a good protection effect because air can easily flow into the teeming system and cause reoxidation of molten steel during teeming. By contrast, an argon shroud protection device seated on the top of the central trumpet provides an excellent protection effect, where air has little chance of flowing into the teeming system during casting. The feasibilities of the argon shroud protection devices are discussed.
文摘Slag carry-over during the draining of molten steel from a teeming ladle is numerically studied here. Two-phase isothermal transient 3D Computational Fluid Dynamics simulations were employed to simulate the draining process. Two nozzle diameters, two nozzle positions and three slag heights were considered. From mass balances, the slag carry-over in terms of mass flow rate was obtained for each of the above variables. Besides, the draining times of the teeming ladle were estimated from theoretical considerations and CDF simulations, and compared.
基金Sponsored by Science and Techonlogy Program of Liaoning Province of China(2008221015)
文摘Steel teeming time is a very important parameter in the new slide gate system with electromagnetic induction （called electromagnetic steel teeming system）, and how to shorten this time is a key to realize application of the new system in continuous casting. The effects of power parameters, coil position, nozzle material and other factors on the steel teeming time were investigated by a self-designed electromagnetic steel teeming system in detail. The experimental results show that the relationship between power and steel teeming time is nonlinear. The coil position has great in- fluence on steel teeming time. And the upper nozzle with high permeability can reduce the teeming time. In addition, the steel teeming time becomes minimum when the size of the spherical cast iron particles is 2.0 ram. This research can provide technical references for the industrial application of the new electromagnetic steel teeming system.
基金This project was supported by National Natural Science Foundation of China(Grant Nos.51974156 and 51974153)Key Laboratory of Sea Industry Steel Ansteel(Grant No.SKLMEA-USTL-201702).
文摘An innovative process of clad teeming was proposed to prepare slab ingot,which featured a built-in cold core to inhibit solidification defects.A 20-kg clad ingot was prepared in the experiment,using a volume ratio of solid core to molten steel of 1:13 and a preheating temperature of cold core of 573 K.Solidification microstructures of the clad ingot were analyzed by comparing with a reference ingot without cold core.Interfacial morphologies and mechanical properties of the clad ingot were studied before and after hot rolling.The effect of cold core on heat transfer and nucleation during the solidification in clad ingot was analyzed.Results show that the solidification microstructures in the clad ingot are refined and homogenized obviously.The grain size in the center of the reference ingot is 2–3 times greater than that of clad ingot,and there is almost no columnar grain in the clad ingot.The interfacial shear strength reaches 318 MPa,which shows excellent metallurgical bonding at the interface of cold core and molten steel.Tiny defects at the interface are eliminated,and interfacial shear strength reaches 426 MPa after hot rolling with a 68.4%total reduction ratio.The experiment and analysis of this process are expected to provide a new idea to prepare large ingots with refinement and homogeneity at a low cost.
