Abstract：In order to investigate the the cause of superficial network cementite defect in 12.5 mm specification 82B hot- rolled wire rob, the superficial microstructures of 82B hot- rolled wire rob were observed, the mass fraction of the superficial carbon was detected after milling the surface of billet, the mould fluxes without carbon were applied and the heating temperature of the billet was adjusted. Results showed that the mass fraction of carbon at different depth from the shallow layer of the billet was normal fluctuation when considering the solidification segregation, and there was on obvious surface recarburization. After milling the billet of 3.0- 5.0 mm from the shallow layer, the superficial network cementite defect also existed in 82B hot- rolled wire rob and had no decreasing trend. And after rolling the billets produced by the mould fluxes without carbon, the superficial network cementite in 82B hot- rolled wire rob still existed and had no decreasing trend neither. After adjusting the initial rolling temperature of the billet from 890- 910 to 960- 1 010 ℃, the superficial network cementite defect in 82B hot- rolled wire rob was not found any longer. Thus, it could be concluded that the reason for the superficial network cementite defect in 12.5 mm specification 82B hot- rolled wire rob produced in the factory was the incorrect heating temperature of the billet, rather than the surface recarburizing of the billet.
2018, Vol. 28 
