Linear Segregation in Low-Pressure Casting ZL205A Alloy Fully Enveloped Castings and its Formation Mechanism

In ZL205A alloy fully enveloped castings, linear segregation has been observed to be a common fault that can cause significant harm to the mechanical properties of the castings. Numerical simulation and similar molding approaches were used to obtain fully enveloped low-pressure castings of ZL205A alloy with linear segregation. Using energy dispersive spectroscopy and scanning electron microscopy, the microstructure of the alloy was examined with the goal to look into the formation mechanism of linear segregation. Results show that when the pressurization pressure P3 = 2P2, the hindered factor epsilon = 0.129, and the sand core is a phenolic resin sand core, linear segregation takes place in fully enveloped low-pressure castings. In addition, the hindered factor of fully enveloped castings is related to the collapsibility of the sand core, the easier the sand core collapses, the higher the hindered factor. There is a significant risk of hot tearing in localized castings connected to the slit gating system. Melt with a high concentration of Cu in the slit gating to feed hot tearing under pressurization pressure. Linear segregation is formed, and the segregation phase is Al2Cu.