Research on Key Technologies of 38CrMoAl Steel Produced by BOF-LF-RH-CC Process

Abstract

Nozzle blockage is easy to take place in continuous casting process when producing 38CrMoAl steel due to high content of aluminum ([Al]=0.7%~1.1%). Slag-steel reaction will lead to large transformation for composition of molten steel and performance of slag on the condition of traditional high content of SiO2 in slag. And it will reduce the cleanliness of steel as well. The control target of refining slag and tundish powder has been gotten through the analysis of refining & continuous casting characteristics of high aluminum steel. Based on this, the content of Si and Al in molten steel can be controlled accurately, and the cleanliness of steel has gone to a higher level. Moreover, mold powder with high basicity and vitrification ensures the stability of slag after sorbing Al2O3 inclusions in theory. Continuous casting can be carried out successfully with the control of inclusion morphology through slag washing during tapping. Industrial practice shows that Si content is 0.25%~0.40%, Al content is 0.80%~1.00%, S content is below 0.004% and T[O] is below 0.0015% in steel products. Moreover, casting bloom with good surface quality is achieved, and the rate of bloom without cleaning is as high as 100%. With all these countermeasures, 38CrMoAl steel can be continuously cast for more than 6 heats.