The casting properties of malleable cast iron are as follows:
1. Poor liquidity
The amount of c and Si of malleable cast iron is low, waste steel is large, and the ferric fluid mobility is poor, therefore, the molten iron is required to have a high furnace temperature and casting temperature (>1360 degrees Celsius) to prevent defects such as cold insulation, insufficient casting and slag inclusion.
2. High casting stress and liquid shrinkage
As the malleablle cast iron is all-white structure, no graphite is precipitated when solidified, making it shrink more than gray cast iron (body contraction is generally 5.3% to 6.0%, and linear contraction is about 1.8%). Therefore, it is easy to produce shrinkage cavity and porosity.High stress, easy to produce deformation and cracking defects.
3. High gas content
With the increase of the superheat temperature of iron solution, the air content increased. Under the same conditions, the air content of gray iron is higher than that of gray iron. Therefore, castings are prone to produce pores, especially subcutaneous pores.