| 摘要 |
<P>PROBLEM TO BE SOLVED: To stably perform smelting of steel with a calcium content of 0.0005 mass% or less using an RH vacuum degassing apparatus without controlling the calcium content of metal or alloy iron for adjustment of molten steel components. <P>SOLUTION: The method for smelting low-calcium steel with a calcium content of 0.0005 mass% or less is provided. When the molten steel component is adjusted by adding metal or alloy iron for component adjustment to molten steel 3 after Al deoxidation which recirculates between a vacuum chamber 5 and a ladle 2 in an RH vacuum degassing apparatus 1, required recirculation time t<SB POS="POST">0</SB>from the final addition time of the metal or the alloy iron for component adjustment is obtained from the following formula (1) where the target calcium concentration C<SB POS="POST">T</SB>is set to be the maximum value of the calcium concentration of the low-calcium steel, the object to be smelted. The required recirculation time t<SB POS="POST">0</SB>obtained is secured, and the molten steel is recirculated within not more than 60 seconds from the required recirculation time t<SB POS="POST">0</SB>, and then the smelting is finished. (1): t<SB POS="POST">0</SB>=ln[(C<SB POS="POST">o</SB>+ΣYai×Rai×Wai×10<SP POS="POST">4</SP>/W)/C<SB POS="POST">T</SB>]/[1×10<SP POS="POST">-7</SP>×G<SP POS="POST">0.5</SP>×A<SP POS="POST">0.5</SP>×Q×ln(1.4×1012/P)]. <P>COPYRIGHT: (C)2013,JPO&INPIT |
