Processing Characteristics of Seamless Steel Pipe Fine Casting
1. Since the shortening of the fine casting of seamless steel pipes greatly surpasses of cast iron, in order to avoid the shortcomings of shrinkage cavities and shrinkage porosity of seamless steel pipes, risers, chilled iron and subsidies are used in the casting process to complete sequential condensation.
In order to avoid shrinkage, shrinkage, porosity, and cracks in seamless steel pipe castings, seamless steel pipes with uniform wall thickness should be made to avoid sharp and right-angle structures. Sawdust is added to the casting sand and coke is added to the core. , And the use of hollow cores and oil sand cores to improve the concession and air permeability of sand molds or cores.
2. Due to the poor fluidity of molten steel, in order to avoid the lack of cold casting of seamless steel pipe castings, the wall thickness of the steel castings should not be less than 8mm; use dry casting or hot casting; appropriate casting temperature, generally 1520°~ 1600°C, due to the high pouring temperature, the high degree of superheat of the molten steel and the long time for liquidity, the fluidity can be improved. However, if the pouring temperature is too high, the seamless steel pipe will cause defects such as coarse grains, hot cracks, pores and sand sticking. Therefore, the pouring temperature of fine castings with small, thin walls and messy shapes about the melting point temperature of steel is 150℃.