Abstract: In order to solve the problem of low qualification rate of inclusions in 40Cr10Si2Mo gas valve steel rolled by special steel factory. The following measures were taken: the evolution rule of the inclusions in the steel from refining to continuous casting was analyzed, and the existing process system was analyzed. On the basis of laboratory research, the continuous casting argon blowing process and the tundish covering fluxes were optimized. After the application of this technology, the qualified rate increased from 71 % to 97 % of the 40Cr10Si2Mo valve steel inclusions.

Key words: 40Cr10Si2Mo, gas valve steel, rolled inclusions rating, molten steel cleanliness