Common defects of 99.9% aluminum ingot used in remelting are:
①Stomata. The main reason is that the casting temperature is too high, there is more gas in the aluminum liquid, there are many air holes (pinholes) on the surface of the aluminum ingot, the surface is dark, and thermal cracks occur in severe cases.
② Slag inclusion. The main reason is that first, the slag is not clean, causing slag inclusion on the surface; second, the temperature of the aluminum liquid is too low, causing slag inclusion inside.
③Ripple and flash. The main reason is that the operation is not precise, the aluminum ingot is too large, or the casting machine is not running smoothly.
④ Crack. The cold crack is mainly caused by the casting temperature being too low, which makes the aluminum ingot crystal not dense, causing looseness and even cracks. Hot cracks are caused by high casting temperature. ⑤ Segregation of ingredients. Mainly caused by uneven stirring during casting of the alloy.