Critical Redistribution of Nitrogen in the Austenitic Cr-Mn Steel under Severe Plastic Deformation

A narrow temperature range of changes in the mechanism and kinetics of structural-phase transformations during mechanical alloying under deformation in rotating Bridgman anvils was determined by the methods of Mossbauer spectroscopy, electron microscopy, and mechanical tests in the high-nitrogen chromium-manganese steel FeMn22Cr18N0.83. The experimentally established temperature region is characterized by a change in the direction of nitrogen redistribution-from an increase in the N content in the metal matrix during cold deformation to a decrease with an increase in the temperature and degree of severe plastic deformation. The change in the direction of nitrogen redistribution is due to the acceleration of the decomposition of a nitrogen-supersaturated solid solution of austenite with the formation of secondary nanocrystalline nitrides. The presence of a transition region for the mechanism of structural-phase transitions is manifested in the abnormal behavior of the mechanical properties of steel.

Automated summary

The study determined a narrow temperature range of changes in the mechanism and kinetics of structural-phase transformations during mechanical alloying in high-nitrogen chromium-manganese steel, leading to abnormal behavior of the mechanical properties of the steel. The direction of nitrogen redistribution was found to change due to the acceleration of the decomposition of nitrogen-supersaturated solid solution of austenite with the formation of secondary nanocrystalline nitrides.