Defects characterization of welded specimens by transmission electron microscopy

Austenitic Type 304L stainless steel (SS) and martensitic Alloy EP-823 have been identified as candidate structural materials to contain spallation arget for transmutation of nuclear waste. Welded specimens consisting of either or both materials have been evaluated by transmission electron icroscopy (TEM) to determine the dislocation density near the heat-affected-zone (HAZ) and the base material. The results indicate that the verage dislocation density determined from the TEM micrographs taken at different locations was much higher near HAZ compared to that of he base material. Further, the estimated dislocation density was higher on the Alloy EP-823 side of the weld than that of the Type 304L SS side ossibly due to the faster rate of solidification of the martensitic alloy. Higher dislocation density is an indication of enhanced residual stress esulting from the welding operation. 2007 Published by Elsevier B.V.