Microstructural Study of High Energy Density Dissimilar Metal Welds

摘要

Electron microscopy analysis of two different CO sub 2 laser welded dissimilar metal combinations revealed the presence of minor constituents which could be attributed to terminal solidification events. In the case of the 15-5 PH/HP 9-4-20 welds, a NbC/austenite eutectic-type constituent was identified, which accounted for the observed fusion-zone hot cracks in these welds. The identity of the interdendritic constituent first observed optically by Patterson and Milewski sup 9 in 304L/625 GTA welds has been confirmed as Laves phase. It was further determined that this phase is enriched in Mo and Nb relative to the austenite matrix. (ERA citation 11:038296)