Large amount of nitrogen addition into an austenitic stainless steel can improve the
mechanical properties and corrosion resistance remarkably as far as the nitrogen is in solid solution.
However, once the nitrogen precipitates as nitride, it results in deteriorations in the properties of the
high nitrogen austenitic stain steel. During welding, a high nitrogen austenitic stainless steel is
ready to precipitate rapidly immense amounts of chromium nitride in the heat affected zone (HAZ),
as intergranular or cellular morphologies at or from grain boundaries into grain interiors. The nitride
precipitation reduces seriously the local mechanical properties and corrosion resistance. The present
authors have demonstrated that a thermomechanical-processing as grain boundary engineering
(GBE) inhibited intergranular chromium carbide precipitation in the HAZ of a type 304 austenitic
stainless steel during welding and improved the intergranular corrosion resistance drastically. In the
present study, the thermomechanical-processing was applied to a high nitrogen austenitic stainless
steel containing 1 mass% nitrogen to suppress the nitride precipitation at or from grain boundaries
in the HAZ during welding by GBE. GBE increases the frequency of coincidence site lattice (CSL)
boundaries in the material so as to improve the intergranular properties, because of strong resistance
of CSL boundaries to intergranular deteriorations. The optimum parameters in the
thermomechanical-processing brought a very high frequency of CSL boundaries in the high
nitrogen austenitic stainless steel. The GBE suppressed the intergranular and cellular nitride
precipitation in the HAZ of the high nitrogen austenitic stainless steel during welding.
Cavitation erosion behavior of high‑nitrogen austenitic stainless steel: Effect and design of grain-boundary characteristics