Numerical and experimental optimization of gating design, pouring parameters, and degassing for gravity-cast A356 aluminum tensile specimens

Gating-system design and pouring parameters are each known to shape aluminum casting quality, yet the two are rarely examined together in a single study. This study proposes an integrated numerical-experimental framework to optimize the gating design and process parameters for A356 aluminum tensile specimens conforming to JIS H5202, using Altair Inspire Cast simulation. Variations in pouring time, pouring temperature, mold preheat temperature, and degassing duration were evaluated to analyze temperature distribution, molten metal flow behavior, and defect formation. Simulation results reveal a stable temperature gradient from the sprue to the specimen tip, supporting gradual solidification without significant hot spots. An increase in pouring time reduces the temperature at the farthest flow point and raises the risk of misrun through heat loss, whereas a higher mold preheat temperature preserves melt fluidity and delays premature solidification. Microstructural analysis shows that, prior to degassing, the alloy exhibits a coarse dendritic α-Al matrix, acicular eutectic silicon, and pronounced gas porosity; after degassing, the microstructure becomes more homogeneous, with reduced secondary dendrite arm spacing and markedly lower porosity. The combined optimization of gating design, thermal parameters, and degassing improved filling stability, reduced casting defects, and increased the ultimate tensile strength to 242.7 MPa. Taken together, these results outline a workflow grounded in simulation and confirmed experimentally that other researchers and foundry practitioners can apply to raise A356 gravity-casting quality and throughput.