Cleanliness study of IF steel by holding in ladles after RH vacuum process

The influence of the holding time of molten steel in the ladle after RH vacuum process on the TO content and nonmetal inclusion content of interstitial-free(IF) steel in the tundish was studied to optimize the RH process parameters and improve the cleanliness of IF steel after RH treatment. Experimental results show that as the holding time increases,the TOand non-metal inclusion contents decrease at first and then increase. The TOcontent is basically steady below 30×10^-4% in the holding time range of 30 min to 40 min except for 4.76% of heats. It is suggested that under current process conditions,the steel mill should control the holding time between 30 min and 40 min.