• duplex stainless steel;
  • aging;
  • precipitation;
  • microstructure


The precipitation and evolution of secondary phases in aged UNS S82441 Duplex Stainless Steel was investigated with morphological observation. The coexistence of nitrides, carbides and sigma and chi phase was found during the initial aging stages. In the initial aging stages, the granular σ and χ phases grow and coalesce according to Ostwald ripening. The intermetallic particles near the austenite/ferrite interfaces tend to grow compared to those in the inner grain. The relationships between aging time and microstructure evolution of this alloy were discussed in detail. After aging, the chromium-depleted zones near the austenite/ferrite interfaces transform to the secondary austenite, while the chromium-depleted zones near the ferrite/ferrite interfaces are replenished with chromium from the matrix.