Research On The Shear And Heat Transfer During The Melt Treatment By The Slope Plate

In this paper, according to the technology of semisolid metals slurry preparation by the slope plate method, it was studied that the heat transfer and solidification of metals under the condition of flow shearing and vibration. The mechanical calculation model of dendrite on the slope plate surface under the condition of flow shearing and vibration was set up. The heat transfer law during the process of preparing the semisolid slurry by the slope plate method was analyzed. Main work and results are described as follows:(1) The flow types of the metallic melt along the slope plate included laminar flow and turbulent flow. When the casting height was not equal to Om, shearing stress of the melt first fell sharply and then leveled off with the flow length increasing in the laminar stage, and gradually increased with the increase of flow length in the turbulent stage. The shearing stress became larger when the melt was close to the plate surface. The bending stress of dendrite on the slope plate surface was the largest in the root. The bending stress of dendrite root on the slope plate surface increased with the increase of casting height and slope angle.(2) When the bending stress of dendrite root was greater than the critical strength or the adhesion strength with the plate surface, the dendrite could break and be free from the slope plate surface. In addition, Vibration could promote the shearing stress and bending stress of the dendrite in the laminar stage. But it had little effect on the bending stress of the dendrite in the turbulent stage.(3) The temperature boundary layer thickness of the melt on the slope plate first increased quickly and then tended to be stable with the increase of flow length. The average heat transfer coefficient between the plate and the melt increased with the slope angle and casting height increasing. The temperature boundary layer thickness under the condition of vibration was smaller than that without vibration.(4) When there was no vibration, the average heat transfer coefficient between the plate and the melt first fell sharply, then leveled off with the increase of the flow length. The average heat transfer coefficient increased gradually with the increase of slope angle and casting height. In addition, vibration could promote the average heat transfer coefficient between the plate and the melt.(5) When there was no vibration, the cooling rate of melt increased gradually with the increase of the flow length. and it was divided into three stages:non-cooling stage, laminar cooling stage and turbulent cooling stage. The cooling rate increased gradually with the increase of flow length in laminar and turbulent cooling stage. In addition, vibration could promote the cooling rate of the melt, and increased steadily with the flow length increasing.