In-Situ Metallography ( Replica Method)

The regions susceptible to metallurgical degradations will be subjected to metallography examination and evaluation will be made on both optical as well Scanning Electron Microscopy. The recommendations derived are pragmatic and would ensure the utilization of full life cycle of the component.

Small area is polished by the portable grinder and polisher and made to mirror finish by employing various steps. The microstructures are prepared by applying suitable etching and subsequently transferred on a plastic tape by replication method. Replication is carried out to arrive at microstructure degradation of the components.

As corrosion damage is concentrated in narrowly limited zones or on uniform zones, replication is most suitable method of detecting these zones. Replica spots may be selected based on metallic thickness and oxide scale measurement and susceptible areas. In general, corrosive failures initiate mostly at surface of the components of complex component geometry associated with major branch connections selected for replica spots as these are vulnerable for corrosion damage.

Microstructures are being viewed under high powered microscopes in the laboratory and judgments are made for different damages mechanisms like to check the heat treatments/ amount of cold worked /carbide precipitation and presence of any ferrite content in the stainless-steel surfaces.