Effect of Nitrogen on Weld Solidification Cracking Susceptibility of Fe-25%Cr-22%Ni-P-N Fully Austenitic Stainless Steels

The effect of nitrogen on weld solidification cracking susceptibility of Fe-25%Cr-22%Ni-P-N fully austenitic stainless steels was experimentally investigated. Maximum crack length in Trans-Varestraint test slightly increased with increasing nitrogen content. Moreover, nitrogen content also did not affect the cracking susceptibility in self-restraint type weld crack test. The observation of liquid Sn quenched microstructure revealed that the addition of nitrogen caused microstructural transition from cell to dendrite, decreasing microsegregation of chromium and phosphorus during solidification. We concluded that brittleness temperature range was not enlarged by nitrogen addition, because the increment related to microsegregation of nitrogen itself and the decrement related to the suppressed microsegregation of chromium and phosphorus canceled each other out.