Formation and growth of complex precipitates in 316L austenitic steel during long-term annealing experiments

Transmission electron microscopy as well as corresponding analytical techniques, such as energy dispersive X-ray analysis, electron energy loss spectroscopy, and elemental mapping via Gatan imaging filter, have been used to study the growth sequence of complex precipitates with a TiN core formed in a commercial 316L(N) austenitic steel after creep experiments at 600 C. It was found that the TiN precipitates, which originally exist in the asdelivered steel, serve as nucleation sites for intermetallic and Cr-containing carbide precipitates. The evolution of precipitate formation and growth was analyzed based on undeformed sample screw heads after 84, 164, 5,481, 41,000, and 85,000 h annealing.