Parameters affecting dephosphorization of stainless steel

University essay from KTH/Materialvetenskap

Abstract: A literary study has been made to find parameters affecting dephosphorization of stainless steel. Ways to lower phosphorus content without major loss of chromium in order to decrease the production costs of Sandvik AB’s stainless steel. The study was conducted with respect to oxidizing dephosphorization and parameters affecting dephosphorization are carbon and chromium content, temperature and slag properties. It was revealed that higher carbon content and basicity is beneficial to the dephosphorization process. However, the choice of temperature, chromium content and flux were dependant on which way dephosphorization was approached. A method of refining chromium in slag using an electric arc furnace (EAF) was also discovered. This made it possible to extract 97% of all chromium in slag. The conclusions are that in order for Sandvik to successfully remove phosphorus, scrap metal with higher carbon content should be used, together with a basic CaO slag with constituents of e g Li2O3 and CaF2. A deslagging step can be added to the argon oxygen decarburizer (AOD) process in order to remove the phosphorus bound to the slag, before decarburization.

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