Investigation of the influence of electric spark discharge on the features of dissolution of gaseous nitrogen in iron-carbon melt

Nitrogen is known as a promising alloying material for special steels with specified properties. It improves service properties, in particular, strength and hardness. Among the existing methods of nitrogen steel alloying, the most common is the use of nitrided ferroalloys. The production, transportation and storage of such ferroalloys have a significant negative impact on the environment. An alternative to this method of introducing nitrogen into an iron-carbon melt is the use of gaseous nitrogen. However, the solubility of nitrogen from the molecular state in liquid iron is extremely limited. It is known that an electric discharge can split a molecule into atoms or form ions. There is very little information on the influence of electric discharges with different characteristics on the absorption of nitrogen by an iron-carbon melt. This is especially true of a spark discharge. The influence of the gas flow and the distance between the electrodes on the spark electric discharge were studied. Rational conditions for nitrogen blowing with activation by a spark electric discharge with single-streamer and a multi-streamer option were obtained. Using a high-temperature study, the effect of a spark-type electric discharge on the efficiency of the nitrogen absorption process by an iron-carbon melt in comparison with conventional nitrogen blowing was studied. It was established that electrical activation of the nitrogen flow allowed to increase its dissolution degree: an average increase in the nitrogen content in the metal after purging by 19.1% in the case of one-streamer discharge application and by 36.2% in the case of multi-streamer discharge application to the nitrogen gas flow compared to the purging option under similar conditions without an electric discharge. The formation of an ion current of positive and negative particles in a nitrogen flow was noted. Accordingly, it is possible to assume the increase in nitrogen solubility at electrical spark discharge activation is due to the active interaction of positively and negatively charged particles with the iron base of the melt.