In continuous casting production,droplet characteristics are important parameters for evaluating the nozzle atomization quality,and have a significant impact on the secondary cooling effect and the slab quality.In ord...In continuous casting production,droplet characteristics are important parameters for evaluating the nozzle atomization quality,and have a significant impact on the secondary cooling effect and the slab quality.In order to study the behavior of atomized droplets after reaching the slab surface and to optimize the spray cooling effect,the influence of droplet diameter and droplet velocity on the migration behavior of droplets in the secondary cooling zone was analyzed by FLUENT software.Results show that the droplets in the spray zone and on the slab surface are mainly concentrated in the center,thus,the liquid volume fraction in the center is higher than that of either side.As the droplet diameter increases,the region of high liquid volume fraction on the slab surface becomes wider,and the liquid phase distribution in the slab width direction becomes uneven.Although increasing the droplet velocity at the nozzle exit has little effect on droplet diffusion in the spray zone,the distribution becomes more uneven due to more liquid reaches the slab surface per unit time.A prediction formula of the maximum water flow rate on the slab surface for specific droplet characteristics was proposed based on dimensionless analysis and validated by simulated data.A nozzle spacing of 210 mm was recommended under the working conditions in this study,which ensures effective coverage of the spray water over the slab surface and enhances the distribution uniformity of water flow rate in the transverse direction.展开更多
Cooling heat flux effect in both primary and secondary cooling zone has been studied in semi-continuous casting of copper billet. Sufficient cooling is essential to reduce casting defects and to get high productivity,...Cooling heat flux effect in both primary and secondary cooling zone has been studied in semi-continuous casting of copper billet. Sufficient cooling is essential to reduce casting defects and to get high productivity, however low rate of solidification is aimed in order to get coarser grain size and softer metal for less losses in extrusion. A three-dimensional numerical model has been developed including solidification behavior of copper through mushy zone. At steady state and constant casting speed, solid shell thickness is monitored during the reduction of cooling rate at mould region to avoid breaking out. Heat flux intensity at mould plays important role not only in the formation of solid shell thickness. But, pool length and mushy zone thickness can be significantly increased by decreasing primary cooling intensity. Increase intensity of secondary cooling zone for two particular cases of primary cooling is tested. First case is tested at mould inlet water temperature of 38°C, and second case at water temperature of 63°C. Results showed that the combination of increasing secondary cooling intensity and reduction of primary cooling intensity can increase pool length and mushy zone thickness. Also, it is shown that, secondary cooling intensity can be magnified by up to 1.5 times for cooling water temperature of 63°C to get pool length close to that of water temperature of 38°C.展开更多
<正>This study analyzes the factors of influence on 0~# continuous caster in No.1 Steelmaking Plant of Xinjiang Bayi Iron & Steel Corporation(hereinafter referred to as Basteel).Diameter of tundish upper noz...<正>This study analyzes the factors of influence on 0~# continuous caster in No.1 Steelmaking Plant of Xinjiang Bayi Iron & Steel Corporation(hereinafter referred to as Basteel).Diameter of tundish upper nozzle is small,and the molten steel leakage accidents have been greatly manifolded in the high casting speed.In order to increase yield of 0~# continuouse caster in No.1 Steelmaking Plant of Xinjiang Bayi Iron & Steel Corporation,and a series of amelioration measure was put forward.Through enlarging diameter of tundish upper nozzle(fromφ21 mm toφ21.5 mm ),after the water distribution of the secondary cooling was optimized.Based on stabilizing the quality,improving the average casting speed and work rate of the caster,the capacity of the billet continuous caster was improved.A better results was gained;the average casting speed had been increased from 3.04 m/min to 3.21 m/min.Production of the caster had been improved from 1 005 179.926 t in 2008 to 1 040 853.075 t in 2009.Quality of the concasting billets and production had also been stabilized.展开更多
A coupled cellular automaton-finite element model was developed to simulate the solidification behavior and structure of 38CrMoAl large round bloom,in which mold electromagnetic stirring+final electromagnetic stirring...A coupled cellular automaton-finite element model was developed to simulate the solidification behavior and structure of 38CrMoAl large round bloom,in which mold electromagnetic stirring+final electromagnetic stirring was taken into consideration,under different superheat,casting speeds,and secondary cooling water flow.Industrial trials for infrared temperature measurement and macro etch experiments of the post-test round bloom samples were used to verify the simulated solidification structure and temperature field.The simulation results show that superheat and secondary cooling water flow have little influence on the surface temperature,center temperature,and center solid fraction while casting speed has a more obvious influence on solidification behavior.With the increase in the casting speed of 0.02 m min^(-1),the solidification position is prolonged by about 1.64 m.With the increasing specific water ratio by 0.02 L kg^(-1) each,the surface temperature of the secondary cooling zones decreases by about 18℃,and the solidification position shortens by about 0.11 m.As the superheat increases from 10 to 40℃,the ratio of the equiaxed crystal zone decreases from 35.98% to 23.98%.The casting speed and secondary cooling water flow increase the equiaxed crystal ratios of the large round bloom,but neither is significant,both being about 2%.展开更多
基金funded by the National Natural Science Foundation of China(Nos.51974213 and 52174324)。
文摘In continuous casting production,droplet characteristics are important parameters for evaluating the nozzle atomization quality,and have a significant impact on the secondary cooling effect and the slab quality.In order to study the behavior of atomized droplets after reaching the slab surface and to optimize the spray cooling effect,the influence of droplet diameter and droplet velocity on the migration behavior of droplets in the secondary cooling zone was analyzed by FLUENT software.Results show that the droplets in the spray zone and on the slab surface are mainly concentrated in the center,thus,the liquid volume fraction in the center is higher than that of either side.As the droplet diameter increases,the region of high liquid volume fraction on the slab surface becomes wider,and the liquid phase distribution in the slab width direction becomes uneven.Although increasing the droplet velocity at the nozzle exit has little effect on droplet diffusion in the spray zone,the distribution becomes more uneven due to more liquid reaches the slab surface per unit time.A prediction formula of the maximum water flow rate on the slab surface for specific droplet characteristics was proposed based on dimensionless analysis and validated by simulated data.A nozzle spacing of 210 mm was recommended under the working conditions in this study,which ensures effective coverage of the spray water over the slab surface and enhances the distribution uniformity of water flow rate in the transverse direction.
文摘Cooling heat flux effect in both primary and secondary cooling zone has been studied in semi-continuous casting of copper billet. Sufficient cooling is essential to reduce casting defects and to get high productivity, however low rate of solidification is aimed in order to get coarser grain size and softer metal for less losses in extrusion. A three-dimensional numerical model has been developed including solidification behavior of copper through mushy zone. At steady state and constant casting speed, solid shell thickness is monitored during the reduction of cooling rate at mould region to avoid breaking out. Heat flux intensity at mould plays important role not only in the formation of solid shell thickness. But, pool length and mushy zone thickness can be significantly increased by decreasing primary cooling intensity. Increase intensity of secondary cooling zone for two particular cases of primary cooling is tested. First case is tested at mould inlet water temperature of 38°C, and second case at water temperature of 63°C. Results showed that the combination of increasing secondary cooling intensity and reduction of primary cooling intensity can increase pool length and mushy zone thickness. Also, it is shown that, secondary cooling intensity can be magnified by up to 1.5 times for cooling water temperature of 63°C to get pool length close to that of water temperature of 38°C.
文摘<正>This study analyzes the factors of influence on 0~# continuous caster in No.1 Steelmaking Plant of Xinjiang Bayi Iron & Steel Corporation(hereinafter referred to as Basteel).Diameter of tundish upper nozzle is small,and the molten steel leakage accidents have been greatly manifolded in the high casting speed.In order to increase yield of 0~# continuouse caster in No.1 Steelmaking Plant of Xinjiang Bayi Iron & Steel Corporation,and a series of amelioration measure was put forward.Through enlarging diameter of tundish upper nozzle(fromφ21 mm toφ21.5 mm ),after the water distribution of the secondary cooling was optimized.Based on stabilizing the quality,improving the average casting speed and work rate of the caster,the capacity of the billet continuous caster was improved.A better results was gained;the average casting speed had been increased from 3.04 m/min to 3.21 m/min.Production of the caster had been improved from 1 005 179.926 t in 2008 to 1 040 853.075 t in 2009.Quality of the concasting billets and production had also been stabilized.
文摘A coupled cellular automaton-finite element model was developed to simulate the solidification behavior and structure of 38CrMoAl large round bloom,in which mold electromagnetic stirring+final electromagnetic stirring was taken into consideration,under different superheat,casting speeds,and secondary cooling water flow.Industrial trials for infrared temperature measurement and macro etch experiments of the post-test round bloom samples were used to verify the simulated solidification structure and temperature field.The simulation results show that superheat and secondary cooling water flow have little influence on the surface temperature,center temperature,and center solid fraction while casting speed has a more obvious influence on solidification behavior.With the increase in the casting speed of 0.02 m min^(-1),the solidification position is prolonged by about 1.64 m.With the increasing specific water ratio by 0.02 L kg^(-1) each,the surface temperature of the secondary cooling zones decreases by about 18℃,and the solidification position shortens by about 0.11 m.As the superheat increases from 10 to 40℃,the ratio of the equiaxed crystal zone decreases from 35.98% to 23.98%.The casting speed and secondary cooling water flow increase the equiaxed crystal ratios of the large round bloom,but neither is significant,both being about 2%.
