Nitrogen pressure during melting can be a basis for the most general classification of steels alloyed by nitrogen. Nitrogen steels are made under normal pressure, and high‐nitrogen steels are made under pressure, being higher atmospheric in special units. Nitrogen, as well as carbon, strengthens and increases the thermal stability of austenite. The smaller size of the nitrogen ion compared with carbon results in smaller nitrides, lower surface energy and higher strengthening effect, and the ability to increase both the strength and corrosion resistance of austenite. Herein, the mechanisms of the influence of nitrogen on the properties of steel, the thermodynamics and kinetics of alloying with nitrogen, the critical concentration of nitrogen, and the influence of nitrogen on the properties of steels are considered. Examples of nitrogen and high‐nitrogen steels, including weld joints, steels with special properties, such as corrosion‐resistant steels in bioactive environments, bactericidal steel, and steels alloyed by C + N, are given.
Nitrogen and AlN solubility in Fe-Mn-Al-N, Fe-Mn-Al-C-N and Fe-Mn-Al-Ni-C-N alloys is calculated using the methods of interaction parameters and up-to-date thermodynamic data. The obtained values of balanced nitrogen solubility in these alloys are rather close to the convergence values obtained for liquid metal according to Thermo-Calc data base. Polythermic sections of the phase diagrams of these alloys are calculated and balanced residual values of dissolved nitrogen are determined for the liquidus and solidus temperatures; these temperatures are lower than nitrogen purity limited values, achieved by the modern technologies (0.0030%) for the most investigated alloys. It is possible to obtain up to 0.010% of dissolved nitrogen in the melts Fe-20%Mn-5%Al and Fe-25%Mn-5%Al at the temperatures of steel melting and alloying by nitrogen (1550-1600 °C), while in presence of carbon and with aluminium content more than 5% this value becomes lower than nitrogen purity limited value. Nitrogen content in a solid solution depends strongly on Al and C content. If Al content is 5 %, the maximal nitrogen content in a solid solution Fe-20%Mn-Al can be equal to 9.3•10-4 % at the solidus temperature. This value does not correspond to possibilities of the up-todate industrial technologies. Thereby, AlN nitrides will form in liquid metal at micro-alloying of the steels of Fe-Mn-Al-Ni-C system by nitrogen, before and during crystallization. At the temperature lower 1100 °C, practically complete whole nitrogen is presented in the form of aluminium nitrides. It is displayed experimentally that complete nitrogen content in these alloys has effect on their strength (σ max) at hot deformation towards its elevation. In the case of warm and cold deformation, the tendency of lowering of alloys strength with increase of nitrogen content in these alloys is observed.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.