Effects of Upward Continuous Casting Parameters on Solidification Behavior of Oxygen-free Copper Billets
The theoretical model of temperature field calculation for ϕ30 mm oxygen-free copper billet was estab-lished,and influence of the upward continuous casting parameters on the microstructure of as-cast oxygen-free copper billet was analyzed by CA-FE method.The results indicate that with the constant cooling intensity and temperature,the solidification position of liquid copper inside the mold moves towards the outlet and the cavitation depth is increased with the continuous increase of the drawing speed,leading to the continuous increase of the outlet temperature,while the relation between the drawing speed and outlet temperature meets the quadratic function.When the cooling intensity and drawing speed are constant,the level height of liquid copper in the mold is increased and solidification position moves upward with the increase of casting temperature,while the cavitation depth has little change.The CA-FE simu-lation results reveal that solidification structure almost consist of a quantity number of coarse columnar crystals under low traction speed with drawing speed as variable,and the columnar grains grow along the drawing direction.With increasing in drawing speed,a fine crystal zone appears on the surface,and the columnar crystals become slender with increasing in amounts,while the angle between columnar crystals and the traction direction is decreased.With the drawing speed increasing to 5.5 mm/s,a small amount of equiaxed crystals appear in the core.With the increase of casting temperature,the quantities,size and growth direction of columnar crystals remain stable with casting tempera-ture as variable,while equiaxed crystals in the core are decreased,which are gradually replaced by columnar crystals.
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