1. Since the shrinkage rate of stainless steel pipe fitting casting is much greater than that of cast iron, in order to prevent shrinkage cavities and shrinkage cavity defects in castings, risers, cold iron, subsidies and other measures are often used during the casting process to achieve sequential solidification.
2. In order to prevent shrinkage, shrinkage, pores and cracks in stainless steel pipe fittings, the wall thickness should be uniform, avoid sharp corners and right-angle structures, add sawdust to the casting sand, and add coke to the core. It is used for hollow sand cores and oil sand cores. To improve the flexibility and air permeability of sand molds or sand cores.
3. Due to the poor fluidity of molten steel, in order to prevent insufficient cold insulation and pouring of steel castings, the wall thickness of steel castings must not be less than 8mm; use dry pouring or hot pouring, and increase the pouring temperature appropriately, generally 1520~1600℃, because the pouring temperature High, the molten steel has a high degree of superheat, can remain liquid for a long time, and has better fluidity. improved. However, if the pouring temperature is too high, defects such as coarse grains, thermal cracks, pores, and sand sticking will occur. Therefore, for generally small, thin-walled, complex-shaped precision castings, the pouring temperature is approximately the melting point temperature of steel + 150C. The structure of the pouring system should be simple and the cross-sectional size should be larger than that of cast iron. Large, thick-walled castings should be poured at a higher temperature than cast iron. Its melting point is about 100°C higher.
