Effect of double-layer-shell sand mold on the residual stress of casting and itself crack tendency

Controlling the solidification of metals is the most essential to prevent defects and realize required quality and mechanical properties of castings. However, the conventional sand mold structure is generally dense and thick, which makes it difficult to accurately control the solidification process of castings. The hollow sand molds prepared by 3D printing technology provide the possibility to adopt measures to control the cooling of castings, but the crack on the mold itself is a new problem. Here, a kind of double-layer-shell structure of hollow sand mold is designed. It is proved that it can effectively reduce the crack tendency of the hollow sand mold, the residual stress of the casting decreases as well. Both experiment and numerical simulation results unveil the mechanism.