The kinetics of nitrogen dissolution in levitation and arc-melted Fe-C-Mn filler metals

Purpose: The influence of melting method on the kinetics of nitrogen absorption by Fe-C-Mn filler metals has been analysed. The industrial heats of the Fe-C-Mn (SpG1) type welding filler metals were selected for own researches. Design/methodology/approach: The research of the nitrogen absorption kinetics was carried out in the levitation and TIG arc-melting conditions in the Ar+N₂ atmosphere. The conditions of experiments were made possibly close to those existing in a molten metal drop in the welding processes. Findings: Based on the models of nitrogen absorption during levitation and arc melting of Fe-C-Mn filler metals, the time-dependent changes of nitrogen content were determined as well as the mass transfer coefficients b and the rates of nitrogen absorption. Nitrogen absorption rate decreases along with the increase of oxygen content in the Fe-C-Mn filler metals arc-melted in the Ar+N₂ atmosphere. Research limitations/implications: Investigation of the Fe-C-Mn complex alloys with the specified amount of impurities makes the detailed analysis of the elementary stages of nitrogen dissolution more difficult, yet brings the experiment conditions closer to those occurring in the actual welding processes. Practical implications: Recognizing the mechanisms of nitrogen absorption under arc and non-arc melting to make possible the control of nitrogen level in the welds. Originality/value: Obtained results explain the influence of oxygen and melting conditions on kinetics of nitrogen dissolution in Fe-C-Mn alloys.