Debasis For Field metallography, identification of transformed phases or precipitating phases may be difficult. For laboratory microscopy of the field in-situ metallography replica may be possible - some times with special efforts. I am not sure if some work had been done on this to identify a phase by special etchant in field metallography (i.e., in-situ replica metallography). Special color identifying etchants, are specifically prepared and are used to know or identify precipitated phases in SS, PH grade SS, Ni alloy grades, Heat resistant grade material. These are identified from shape, size, type of precipitates . These are mostly used in laboratory optical metallography or for TEM studies to diagnoze and identify precipitating phases like NbC, TiC, Cr2N, sigma, special high temperature transformation oxide and nitride bearing precipitate effects in high temperature use materials like SS, heat resistant material, high alloy nickel materials, advanced materials used for high temperature use . Off hand- i do not remember the type of special etchants to be used for only diagnosing NbC. For some studies, we have used quite long years back and identified different precipitates in heat resistant and high nickel alloy materials. For your information: NbC precipitation in SS is beneficial and not detrimental to the log term use of SS material. Even after prolonged usage or short term NbC is not detrimental to SS. Thermal stabilizing anneal is a short term phenomenon. It is mostly restircted to a few hours only. NbC precipitates for service use materials of SS with prolonged holding at particular temperature use is a long term effect. This is known to be beneficial and not detrimental. Hope this helps you C.V.Srinivasan Nishi Engineers Pvt Ltd India March 11, 2008 E-mail: nishi@vsnl.com >Presence of Niobium carbide (NbC) precipitate distribution >is obtained by Thermal Stabilisation Annealing treatment on >SS 347 grade austenitic SS in order to improve it's creep >rupture long term performance in service. > >It is very rare to identify this NbC by Optical Microscopy/ >In-Situ Metallography. Does any one having any experience of >field metallography technique to approach resolution to >assess NbC and can declare on-spot that the effect of >stabilisation annealing has not been damaged in-service ? > >regards