According to the previous experimental analysis, the next plan is proposed: accelerate the discharge of carbon in the white mold and reduce the impact of slag inclusion on lost steam steel casting crack. Process requirements: slagging before tapping and secondary slagging in ladle shall be cleaned. The surface of the ladle is covered with refractory asbestos, which plays the role of slag collection and thermal insulation. Special personnel are assigned to stop slag during casting.
Condition: the model is 14~16kg/m3 density foam, open open riser casting (including solid casting and shell casting).
The fourth batch of lost steam steel casting: open riser full mold casting. On December 11, 2015, three boilers a, B and C. Molten steel carbon distribution still goes to the lower limit. The carbon content before tapping is 0.23%, 0.23% and 0.25% respectively. The test method is the same as above. The data are as follows:
Conclusion: the trend of carbon content is still increasing from the core to the surface. But the range is small. The maximum carbon increase is about 0.04%. All sample components are qualified.
The fifth batch of lost steam steel casting: open riser empty shell casting, three furnaces a, B and C on December 20, 2015. Carbon shall be distributed according to the centerline. The carbon content before tapping is 0.28%, 0.27% and 0.25% respectively. The test method is the same as above. The data are as follows:
Conclusion: the carbon content is evenly distributed, and the fluctuation of trace carbon content is related to the burning degree of the foam. The carburization phenomenon was solved and all samples were qualified.
In the second stage, after low steam steel casting annealing, the machining is easy and the hardness is qualified. After quenching and tempering treatment, there was no lost steam steel casting crack, and the hardness value was in a reasonable range. Several lost steam steel casting were damaged, and no internal defects were found.