コールドクルーシブル浮揚溶解による極低リンステンレス鋼の溶製
2002 年 88 巻 7 号 p. 413-418
詳細
2002 年 88 巻 7 号 p. 413-418
For the purpose of creating super-low phosphorus stainless steel with high corrosion resistance, dephosphorization behavior of SUS316L stainless steel was experimentally studied by using Ca-CaF2 flux in a cold crucible levitation melting process.
Dephosphorization, which proceeded immediately after flux addition, was more effective in lower temperature and depended upon the amount of Ca in Ca-CaF2 flux. And also rephosphorization phenomena were observed when the Ca concentration in molten metal decreased by vaporization of Ca in both molten metal and flux.
In this reductional dephosphorization process, the relation between P and Ca concentrations in molten stainless steel just after dephosphorizing treatment by Ca-CaF2 flux addition, is described as following equation,
[%P]2[%Ca]3 = 6.6× 10-11.
The mechanism of dephosphorization and rephosphorization were discussed based on the analyzed P and Ca contents in molten metals.
As a result, by the present dephosphorization process for a commercial stainless steel with 0.025% P, the super-low phosphorus stainless steel with phosphorus concentration below 0.0002% P was attained.
