Abstract:In order to study the law of hydrogen content variation of molten steel and the influence on flaw detection, the hydrogen content in LF refining process was measured by HYDRIS hydrogen analyzer. The results show that temperature raising period, Ca-treatment and soft blowing argon period are the main hydrogen increasing process, as the 83.33% increasing content are 64×10-4 and 46×10-4 respectively. The water in refining slag and submerged arc slag leaded to hydrogen content increasing in temperature raising period, while too fast wire-feeding speed leaded to hydrogen content increasing in Ca-treatment and soft blowing argon period. In addition, the desulfuration and alloying period was another important process for hydrogen increasing as the 16.67% increasing content was 0.22×10-6, and the inducement for this was long time of large blowing argon. The flaw detection qualification rate decreased gradually as the hydrogen content increased in molten steel and the flaw detection qualification rate can reach to 100% when hydrogen content was less than (3-4)×10-6.