In this work, we describe the precipitation behavior of cold-worked titanium-stabilized Type 316 stainless steel irradiated with neutrons in the temperature range of 464 to 596°C. The samples were cut from a Rapsodie fuel pin cladding and were examined by transmission electron microscopy and energy dispersive X-ray micro-analysis.
The microstructure is characterized by the precipitation of G and eta phases in the temperature range of 464 to 521°C, and TiC and Laves phases above 590°C. The results also emphasize the important effect of dose rate on the precipitation, and particularly on the chemical composition of the Laves phases. The most striking feature is the appearance above 546°C of thin platelets whose diffraction characteristics are coherent with the hexagonal Ni3Ti phase. The formation of a high density of these planar may partly explain the low swelling of cold-worked titanium-stabilized Type 316 stainless steel above 540°C.