Research on Cleanness of IF Steel Slab Produced in Unsteady Casting Process

In order to research the impact of unsteady casting process on IF steel slab,the cleanness of IF steel slab of unsteady casting conditions produced by the converter-RH-CC process was investigated by means of gas analysis,chemical composition analysis and big sample electrolysis of first slab,last slab and SEN-changing slab.The results show that TO,N,C content of the first slab rises along with the casting direction while Al and Ti content is just the opposite;average TO content of the whole first slab is 0.001 5% higher than other slabs,and N content 0.000 5% higher than other slabs,C content exceeds the criteria;the highest TO content of last slab and SEN-changing slab is 1.6 and 2.2 times average level of normal slabs,N content of last slab and SEN-changing slab fluctuation is 1.0-1.3 and 1.5-1.7 times average level of normal slabs,C content of last slab and SEN-changing slab fluctuation is 1.2-1.4 and 1.2-2.1 times average level of normal slabs,while other composition of last slab and SEN-changing slab has not very big fluctuation;content of large-sized inclusion of first slab is 34.37 mg/(10 kg) which is the highest,and then the last slab,and then the SEN-changing slab,ladle-casting-stop slab,content of large-sized inclusion of the normal slab is lower than 1.24 mg/(10 kg).