Effect of mold and core preheating temperature on corrosion resistance of casting Al-12Si alloy U-shaped cooling channel

Abstract

Temperature has an important impact on the corrosion resistance of mold with cooling channels prepared by casting method. The effect of preheating temperature of the mold and the carbon fiber core on the roughness and corrosion resistance of U-shaped cooling channels made of Al-12Si alloy was examined in depth. The experimental results suggest that as the preheating temperature increased from 273 K to 573 K, the roughness of the inner wall of the cooling channel reduced from 96.6 µ m to 77.0 µm. When the preheating temperature continued to increase to 723 K, the roughness increased to 85.3 µm. The wetting between the Al melt and the carbon fiber will reduce micro bubbles and waves on the channel wall as the preheating temperature rises, thereby reducing the roughness. However, with the further increase of preheating temperature, it will increase the solidification time of the Al melt. At this time, the carbon fiber and Al melt will take more time to react, which increases the roughness of the channel wall to a certain extent. The results of exfoliation corrosion show that the larger roughness will aggravate exfoliation corrosion. The prolongation of high temperature reaction time between the carbon fiber and the Al melt will lead to the segregation of Si, which is easy to cause intergranular corrosion. Therefore, reasonable preheating temperature has an important impact on the roughness and corrosion resistance of U-shaped cooling channels.