Nanoscale chromium carbides induced abnormal hardness in dissimilar metal welds

Abstract

This study showed that high-density nano-precipitates, which have not been observed before, formed in the carbon-enriched zone located 20\u2009µm away from the fusion boundary of the dissimilar metal welds of Alloy 52M and A508 steel. The nano-precipitate, which was named as CrCx in this study, was in a rodlike shape and shorter than 30\u2009nm. The atoms of CrCx were arranged as a face-centered cubic (FCC) crystal. The CrCx precipitates have a lattice parameter of 4.08 Å and a cube-on-cube orientation relationship with the austenitic matrix of Alloy 52M. The results will be of great benefit to the development of advanced dissimilar metal welds and new Ni-based alloys serviceable in a harsh environment.