Production of Low Phosphorous Stainless Steel by the Reducing Dephosphorization Process

Abstract

In order to produce stainless steel with low phosphorous content below 0.01%, experiments were carried out to find optimum conditions for the dephosphorization by metallic Ca and CaC₂. The results are summarized as follows:
(1) Dephosphorization by metallic Ca should be done at temperatures below the boiling point of Ca and the composition of the steel has to be determined not to precipitate CaC₂.
(2) On the other hand, dephosphorization by CaC₂ is effective at high temperatures, where the composition of the steel has to be selected to keep the activity of carbon in the range 0.02-0.3 (at 1600°C).
(3) Based upon the experiments, a new process of mixing two melts, one of which is Cr free steel dephosphorized by conventional oxidizing method and the other is Cr containing steel dephosphorized by Ca or CaC₂, has been developed to attain P content less than 0.01%.