| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To reduce S, C, and Si in a high Ni-Fe alloy steel into an extremely low level through EF-LF-RH steps, and control a form of non-metallic inclusions into MnO-Al<SB>2</SB>O<SB>3</SB>-SiO<SB>2</SB>which is low-melting plastic spessartite, without producing Al<SB>2</SB>O<SB>3</SB>of non-metallic inclusions in a secondary refining step. <P>SOLUTION: This method for manufacturing the high Ni-Fe alloy steel containing Si≤0.03%, C≤0.006%, S≤30 ppm and O<SB>2</SB>≤60 ppm comprises the steps of: melting scrap and an alloy in an EF; using a slag of high basicity in a LF; refining, desulfurizing, and removing the slag of the high basicity in the steps of the LF to the end of RH, without using metal Al except impurities; charging a flux of low basicity containing Al<SB>2</SB>O<SB>3</SB>into the LF and replacing the previous slag with the resultant slag; adding Si into the LF in a deoxidation operation and finishing the step of the LF; blowing oxygen into molten steel in the RH to decarbonize and desiliconize the molten steel, while leaving Si in the molten steel during the decarbonization operation; deoxidizing the molten steel by charging Mn of high C and Si after having finished the decarbonization operation; promoting a deoxidation reaction in the molten steel and a reduction reaction of Al<SB>2</SB>O<SB>3</SB>after a period of stirring; and controlling the form of the non-metallic inclusions into MnO-Al<SB>2</SB>O<SB>3</SB>-SiO<SB>2</SB>of the spessartite. <P>COPYRIGHT: (C)2009,JPO&INPIT</p> |
