Research on the Influence of Casting Process on Hot tearing Tendency of 7050 Aluminum Alloy

The wide solidification range, low thermal conductivity, and high coefficient of thermal expansion of 7050 aluminum alloy result in significant temperature gradients within the casting during the solidification process, thereby increasing the material's susceptibility to hot tearing. This study employed a self-designed experimental platform to measure the solidification shrinkage stress and temperature variations of 7050 aluminum alloy castings. By altering the mold preheating temperature, length of casting, and implementing mold insulation, the hot tearing tendency of 7050 aluminum alloy under different casting processes was analyzed. The results indicate that preheating the mold to 300 °C or preheating it to 200 °C and maintaining that temperature can completely eliminate hot tearing in the casting. The length of the casting was directly proportional to its susceptibility to hot tearing; when the length reached 200mm, hot tearing in the casting led to complete fracture. Mold insulation significantly reduced the number of solidification shrinkage-induced stresses, thereby reducing the tendency for hot tearing. However, as the mold preheating temperature increased, the effectiveness of mold insulation diminished. An increase in length of casting led to an increase in the number of solidification shrinkage stress release cycles, indicating an escalating trend in hot tearing propagation.