Nitrogen Absorption in Molten Stainless Steel During Immersion Nitrogen Blowing

Nitrogen solubility in molten stainless steel of AISI 304,316 and 420 has been investigated by immersion nitrogen blowing through an immersed alumina nozzle with 3mm in I.D.The effects of temperature and nitrogen partial pressure on the nitrogen solubility has also been investigated.Nitrogen solubility at different temperatures and nitrogen pressure for these three grades of steel have been given.The model of nitrogen solubility was validated.Results show that(1) Saturated solubility of nitrogen for AISI 304 at 100 kPa of nitrogen partial pressure and at 1 540℃ and 1 580℃ are 0.234% and 0.206% respectively.The values for AISI 316 at 100 kPa of nitrogen partial pressure and at 1 500℃,1 540℃ and 1 580℃ are respectively 0.22%、0.2% and 0.17wt%.The values for AISI 420 at 100 kPa of nitrogen partial pressure and at 1 510℃ and 1 540℃ are 0.14% and 0.13wt% respectively.The saturated solubility of nitrogen decreases with temperature.(2) Saturated solubility of nitrogen for AISI 316 at 1 540℃ and at nitrogen partial pressure of 20 kPa,40 kPa,60 kPa,80 kPa and 100 kPa are 0.10%、0.14%、0.16%、0.18% and 0.20wt% respectively.Saturated solubility of nitrogen is in direct proportion to the square root of nitrogen partial pressure.