Weldability and microstructural analysis of nuclear grade austenitic stainless steels.

摘要

This study evaluated the hot ductility response, and hot cracking susceptibility (fusion zone solidification cracking and HAZ liquation cracking) of modified nuclear grade and standard austenitic stainless steels. Extensive microstructural characterization using state-of-the art analytical electron microscopy (TEM and STEM) as well as SEM (EDAX) and OLM was performed to correlate the material behavior with metallurgical characteristics. In addition, studies of the effect of Si, N, and rare earth elements on hot cracking susceptibility, significance of the ductility dip phenomena and backfilled solidification cracks were also performed. Furthermore, based on the metallurgical evaluation, the possible mechanisms involved in solidification cracking and HAZ liquation cracking of the modified alloys are proposed. Finally, the optimized chemical specifications and requirements for nuclear grade stainless steels are also suggested.