A steady three-dimensional fluid flow and solidification model was built based on CFD software by high-Reynolds-number and Lam-Bremhorst low-Reynolds-number k-ε model.During the simulation,the fixed-grid enthalpy-por...A steady three-dimensional fluid flow and solidification model was built based on CFD software by high-Reynolds-number and Lam-Bremhorst low-Reynolds-number k-ε model.During the simulation,the fixed-grid enthalpy-porosity technique was used to represent the solidification,and Darcy law was adopted to simulate the flow in mushy region.The prediction for steel flow and solidification was evaluated by the comparison of two turbulence models.It is found that both Lam-Bremhorst low-Reynolds-number and high-Reynolds-number k-ε models predict the same trend of the steel flow and temperature distribution.However,due to the effect of turbulent flow on heat transfer,the low-Reynolds-number turbulence model predicts longer penetration depth of molten steel in sub-mold region,less shell growth and higher shell surface temperature at the narrow face compared with standard k-ε model.展开更多
A steady three-dimensional fluid flow and solidification model was built based on CFD software by high-Reynolds-number and Lam-Bremhorst low-Reynolds-number k-ε model. During the simulation, the fixed-grid enthalpy-p...A steady three-dimensional fluid flow and solidification model was built based on CFD software by high-Reynolds-number and Lam-Bremhorst low-Reynolds-number k-ε model. During the simulation, the fixed-grid enthalpy-porosity technique was used to represent the solidification, and Darcy law was adopted to simulate the flow in mushy region. The prediction for steel flow and solidification was evaluated by the comparison of two turbulence models. It is found that both Lam-Bremhorst low-Reynolds-number and high-Reynolds-number k-ε models predict the same trend of the steel flow and temperature distribution. However, due to the effect of turbulent flow on heat transfer, the low-Reynolds-number turbulence model predicts longer penetration depth of molten steel in sub-mold region, less shell growth and higher shell surface temperature at the narrow face compared with standard k-ε model.展开更多
The triangular zone cracks in 2101 duplex stainless steel produced by the vertical continuous caster have troubled company A for a long time. To simulate the temperature and thermal stress distributions in the solidif...The triangular zone cracks in 2101 duplex stainless steel produced by the vertical continuous caster have troubled company A for a long time. To simulate the temperature and thermal stress distributions in the solidification process of 2101 duplex stainless steel produced by the vertical continuous caster, a two-dimensional viscoelastic-plastic thermomechanically coupled finite element model was established by the secondary development of the commercial nonlinear finite element analysis software MSC Marc. The results show that the thermal stress on the surface reaches a maximum at the exit of the mould, and the highest thermal stresses at the centre of the wide face and the narrow face are 75 and 115 MPa, respectively. Meanwhile, the internal temperature of slab is still higher than the solidus temperature, resulting in no thermal stress. The slab shows different high-temperature strengths and suffers from different stresses at different positions; thus, the risk of cracking also varies. At a location of 6-8 m from the meniscus, the temperature of the triangular zone is 1270-1360℃ and the corresponding permissible high-temperature strength is about 10-30 MPa, while the thermal stress at this time is 60 MPa, which is higher than the high-temperature strength. As a result, triangular zone cracks form easily.展开更多
High-efficiency production organization should be simple and "laminar". A one to one "laminar flow" operation mechanism is supposed to be accepted as a prerequisite to build high-efficiency clean s...High-efficiency production organization should be simple and "laminar". A one to one "laminar flow" operation mechanism is supposed to be accepted as a prerequisite to build high-efficiency clean steel "production platform". Concerning the fact that establishing a one to one "laminar flow" production pattern is impossible at Tangshan Iron and Steel Co., Ltd., "quasi-laminar flow" production pattern was evaluated. Result shows that rolling bar products of various specifications have great impact on the liquid steel supply model between BOF and CC. Considering the process matching issue of steelmaking-continuous casting-rolling process in bar production line, a "quasi-laminar flow" production pattern between BOF and CC was proposed according to different rolling specification in bar mills. Through analysis and research on current production pattern, combined with principles and strategy for BOF workshop control, and taking the plant layout into account, "quasi-laminar flow" production pattern was finally established. Moreover, Gantt chart of "quasi-laminar flow" production pattern was drawn. It is shown that the relative "order degree" of the "quasi-laminar flow" production pattern rises, which is conductive to production scheduling and ladle operation turnaround in comparison with "turbulence" production pattern. While a careful evaluation should be conducted due to the fluctuant temperature drop caused by the inevitable inserted heats and decreased operation rate of inserted BOF before adapting the production pattern.展开更多
文摘A steady three-dimensional fluid flow and solidification model was built based on CFD software by high-Reynolds-number and Lam-Bremhorst low-Reynolds-number k-ε model.During the simulation,the fixed-grid enthalpy-porosity technique was used to represent the solidification,and Darcy law was adopted to simulate the flow in mushy region.The prediction for steel flow and solidification was evaluated by the comparison of two turbulence models.It is found that both Lam-Bremhorst low-Reynolds-number and high-Reynolds-number k-ε models predict the same trend of the steel flow and temperature distribution.However,due to the effect of turbulent flow on heat transfer,the low-Reynolds-number turbulence model predicts longer penetration depth of molten steel in sub-mold region,less shell growth and higher shell surface temperature at the narrow face compared with standard k-ε model.
文摘A steady three-dimensional fluid flow and solidification model was built based on CFD software by high-Reynolds-number and Lam-Bremhorst low-Reynolds-number k-ε model. During the simulation, the fixed-grid enthalpy-porosity technique was used to represent the solidification, and Darcy law was adopted to simulate the flow in mushy region. The prediction for steel flow and solidification was evaluated by the comparison of two turbulence models. It is found that both Lam-Bremhorst low-Reynolds-number and high-Reynolds-number k-ε models predict the same trend of the steel flow and temperature distribution. However, due to the effect of turbulent flow on heat transfer, the low-Reynolds-number turbulence model predicts longer penetration depth of molten steel in sub-mold region, less shell growth and higher shell surface temperature at the narrow face compared with standard k-ε model.
文摘The triangular zone cracks in 2101 duplex stainless steel produced by the vertical continuous caster have troubled company A for a long time. To simulate the temperature and thermal stress distributions in the solidification process of 2101 duplex stainless steel produced by the vertical continuous caster, a two-dimensional viscoelastic-plastic thermomechanically coupled finite element model was established by the secondary development of the commercial nonlinear finite element analysis software MSC Marc. The results show that the thermal stress on the surface reaches a maximum at the exit of the mould, and the highest thermal stresses at the centre of the wide face and the narrow face are 75 and 115 MPa, respectively. Meanwhile, the internal temperature of slab is still higher than the solidus temperature, resulting in no thermal stress. The slab shows different high-temperature strengths and suffers from different stresses at different positions; thus, the risk of cracking also varies. At a location of 6-8 m from the meniscus, the temperature of the triangular zone is 1270-1360℃ and the corresponding permissible high-temperature strength is about 10-30 MPa, while the thermal stress at this time is 60 MPa, which is higher than the high-temperature strength. As a result, triangular zone cracks form easily.
文摘High-efficiency production organization should be simple and "laminar". A one to one "laminar flow" operation mechanism is supposed to be accepted as a prerequisite to build high-efficiency clean steel "production platform". Concerning the fact that establishing a one to one "laminar flow" production pattern is impossible at Tangshan Iron and Steel Co., Ltd., "quasi-laminar flow" production pattern was evaluated. Result shows that rolling bar products of various specifications have great impact on the liquid steel supply model between BOF and CC. Considering the process matching issue of steelmaking-continuous casting-rolling process in bar production line, a "quasi-laminar flow" production pattern between BOF and CC was proposed according to different rolling specification in bar mills. Through analysis and research on current production pattern, combined with principles and strategy for BOF workshop control, and taking the plant layout into account, "quasi-laminar flow" production pattern was finally established. Moreover, Gantt chart of "quasi-laminar flow" production pattern was drawn. It is shown that the relative "order degree" of the "quasi-laminar flow" production pattern rises, which is conductive to production scheduling and ladle operation turnaround in comparison with "turbulence" production pattern. While a careful evaluation should be conducted due to the fluctuant temperature drop caused by the inevitable inserted heats and decreased operation rate of inserted BOF before adapting the production pattern.
