How to smelt high-nitrogen steel (HNS) by blowing ammonia gas in AOD proceess

Recently, the development of high - nitrogen steel (HNS) alloys stand out as a remarkable technological achievement due to significant decrease of raw material costs such as the share of nickel in steel price. However, the date about metallurgy under pressure using low- priced nitrogen gas is insufficient to recover the "additional expenditures" for large-scale production of HNS. According to the technical regulation of AOD process, the coupling reaction of NH3 with O,S as surface activity element in liquid steel, NH3 + 3/2 [O] = [N] + 3/2 H2O and NH3 + 3/2[S]=[N]+3/2 H-2 S would be favorable to absorbing of nitrogen in liquid steel, because,of the metallurgical thermodynamics and the generation of activity nitrogen action. At the same time, blowing ammonia gas can remove the oxygen and sulfur impurity elements during the final period of AOD, which means cancellation of pre - deoxidization and pre - desulfurization with adding some ferro - alloys. Based on the experiments of HNS melting in laboratory, the nitrogen alloying kinetics and the control of hydrogen in the liquid steel under blowing ammonia condition were discussed.