Dephosphorization of stainless steel and high Cr-high Ni-high Mo alloys

Investigation was carried out about dephosphorization by both oxidizing and reducing of 10-20%Cr metals using several kinds of flux, such as Na2CO3-NaCl, K2CO3-KCl, CaO-CaF2, BaO-BaCl2, CaC2-CaF2 and CaCN2-CaF2. It was recognized that CaC2-20%CaF2 flux was adequate to dephosphorization of high Cr content molten metal, because higher Cr content was advantageous for dephosphorization and high degree of dephosphorization was obtained. Experiments of dephosphorization was carried out with CaC2-20% CaF2 flux and it was applied to high Cr, high Ni, high Mo commercial alloys. The results are summerrized as follows: 1) S, N and O contents in addition to P of the molten metals reduced after flux addition, and carbon increased. 2) The effects of alloying elements on dephosphorization are that Cr is advantageous, Ni is disadvantageous, and Mo, Si, Mn have little influence. 3) Because of rephosphorization, the slag after dephosphorization should be completely cut off. 4) The stink of the slag after dephosphorization can be extinguished by wasted nitricacid treatment. (author)