Procedure Of Production Of The Thin-Wall Casting With Feeder Wire Process

Wire Feeding technology has many advantages such as more returns addition, low cost, easier control of residual magnesium, less slag quality and so on. But in the production of thin wall nodular iron castings, it has the defaults that the white structure and hard spots can easily be formed, deteriorating the mechanical properties.This paper analyzed the forming causes of white structure. The base iron with very low sulphur content and high RE makes the white structure. In the thin wall nodular iron castings, the best RE/S is 1~3. The thin wall nodular iron castings will fracture with much more carbon forming, when the RE/S is above 8.This paper studied the effects of sulphur in base iron and residual RE on microstructure of thin wall nodular iron castings. The base iron with very low sulphur content makes the chilling tendency to be intensive; the carbon qualities increase with sulphur decreasing in base iron. In the test, the max carbon qualities is 70%, the min is 3%, the average is the 35% with 0.001%~0.005% sulphur content in the base iron. The carbon qualities increase with residual RE increasing. In the test, with 0.010%~0.015% residual RE content, the carbon qualities is the lowest, the max carbon qualities is 5%. In the production of thin wall nodular iron castings, the good method of solving white fracture is increasing sulphur in base iron, the content of sulphur should be kept in the range 0.010%~0.025%.The white fracture tendency of thin wall nodular iron casting still has relation with storing time of base molten iron, inoculation method, cored wire injection qualities, wire feeding rate and pouring time and so on. In procedure controlling, we adopted increasing carbon in furnace and 3 times inoculation method. The best cored wire injection qualities is 10~12m in the 600 kg molten iron. The best wire feeding rate is 12m/min. The pouring time of one ladle is in 8 min.