1. Since the casting shrinkage of stainless steel pipe fittings is much higher than that of cast iron, to prevent shrinkage cavities and shrinkage defects in castings, measures such as risers, cold iron, and subsidies are mostly used in the casting process to achieve sequential solidification.
2. To prevent shrinkage cavity, shrinkage porosity, porosity and crack defects of stainless steel pipe fittings, the wall thickness should be uniform, sharp corners and right-angle structures should be avoided, sawdust should be added to the casting sand, coke should be added to the core, and the use of Hollow cores and oil sand cores are used to improve the concession and air permeability of sand molds or cores.
3. Due to the poor fluidity of molten steel, to prevent cold shut and insufficient pouring of steel castings, the wall thickness of steel castings should not be less than 8mm; dry casting or hot casting should be used, and the pouring temperature should be appropriately increased, generally 1520~1600 ℃, because the pouring temperature is high, the superheat of molten steel is large, and the liquid state can be kept for a long time, and the fluidity can be improved. However, if the pouring temperature is too high, it will cause defects such as coarse grains, hot cracks, pores, and sand sticking. Therefore, for small, thin-walled, and complex-shaped precision castings, the pouring temperature is about the melting point of steel + 150°C. The structure of the pouring system is as simple as possible, and the cross-sectional size is larger than that of cast iron; Its melting point is about 100°C higher.
Post time: May-10-2023