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How to prevent defects in the steel casting process

by Guest28110545  |  6 years ago

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Steel casting is used in alomst all the industrial sectors,therefore,it has a wide range,such as pump casting parts,machine tool castings,construction machinery castings,mining machinery castings and so on.

The mechanical properties of the cast steel is higher than cast iron,but the casting properties of it is worse than cast iron.Because the melting point of cast steel is higher, liquid steel is easily oxidated,hard to flow and shrink seriously,so it’s volume shrinkage is 10-14% and linear shrinkage is 1.8-2.5%.To prevent steel cast to produce defect,such as short run,cold shut,sinkhole,shrinkage porosity,flaw,burnt-on sand and so on,the process measures which is more complex then cast iron must be taken.

1,Because steel liquid has bad mobility,in order to prevent steel cast cold shut and short run,the thickness of steel cast is not less than 8mm;Gating system is strived for a simple and sectional dimension is biger than cast iron;Dry mold or hot mold is used;We should increasing pouring temperature,which is always 1520-1600℃,because of the high pouring temperature, Liquid steel superheat is large and there is long time to remain liquid,so liquidity can be improved.But too high pouring temperature will cause the defect,such as coarse grains,hot cracking, porosity adhering sand and so on.Generally,for small, thin wall and complex casting,the pouring temperature is about the melting temperature of the steel+150℃;For big,thick wall casting,the pouring temperature is about 100℃ higher than it’s melting temperature.

2, Due to the shrinkage of casting steel is more than iron,to prevent sinkhole,shrinkage porosity,it is almost used the measures,such as dead head,cold iron,subsidy and so on,so that realize sequential solidification.

The steel cast has high melting point and it’s pouring temperature is high,too.It is easily to produce metal penetration defect when molten steel and the mold material interactes under high temperature.So artificial quartz should be used as casting mould and brush in the casting surface by quartz powder or zircon sand powder coating system.In order to reduce the gas and improve steel liquid’s mobility and the strength of mould,most of the steel casting is casted with dry or fast dry type,such as sodium silicate sand mold used CO2 to harden.

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 Tags: Casting, defects, prevent, process, steel

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