Structure

Abstract

The structure of steels with a high content of carbon + nitrogen is analysed in the following sequence: atomic interactions → atomic distribution → thermodynamic stability of solid solutions → properties of dislocations → impact on mechanical properties. A crucial point of this analysis is the effect of alloying with carbon + nitrogen on the electron structure, namely on the ratio between the free and localized electrons in the external electron shell of the atoms, which is responsible for the crystal structure and the compliancy of metals and alloys to the mechanical loading. It is shown that alloying of steels with carbon + nitrogen significantly increases the concentration of free electrons, which assists short-range atomic ordering in the solid solution, improves their nanoscale chemical homogeneity and provides a higher stability to phase transformations and precipitates. The concentration of free electrons also controls the stacking fault energy, i.e. the dislocation splitting, which is important for mechanical properties. The nature of structural changes by loading, namely cold work hardening, effects of subzero temperatures, strain rate and cyclic loading is discussed paying due attention to the effect of carbon + nitrogen on the interatomic bonds.KeywordsFree ElectronPlanar SlipStack Fault EnergyAustenitic SteelInterstitial AtomThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.