PMI SPECIALISTS, INC "WHEN YOU NEED TO KNOW"
Field & In-situ Metallography and Replication
As an NDE method, Field
metallography is widely used for microstructure
analysis on large structures that cannot be easily moved or destructive
sample preparation is difficult or not permissible, such as storage
tanks, piping system, large machinary, boilers or aging high temp
pressure vessels. In-situ Metallography allows for
quick on-site evaluation of a component’s metallurgical and heat
treatment condition. Grain size and grain flow, carbides, cracks and
undesired phases can be readily identified.
In fact, field metallography is the most accurate way to identify high
temperature hydrogen attack (HTHA) and early stage Stress Corrosion
Cracking (SCC).
It
is a powerful tool in assisting materials identification, health
monitoring, remaining life assessment study or failure analysis. On
site metallurgical sample preparation poses more difficulties in many
cases as inappropriate polishing and etching procedure might introduce
artifacts which complicate actual microstructure interpretation. PMI
specialists has a highly skilled and well-equipped team to perform
filed metallography.
The normal procedure is as follows: portable grinder and polisher are used for on-site sample preparation. Then a field microscope is used to examine the quality of the polish. After a satisfactory finishing is achieved, a compatible chemical etchant is used to reveal the microstructure of the polished spot. If desired, electrochemical etching can also be performed. Finally digital images can be taken by a portable microscope with various magnification from 20x, 100x, 200x to 400x magnifications. If needed, we can even take micrographs at 1000x magnification through proprierty techniques, which nobody else in the world have tried or achieved.
If even greater resolution is required, PMI specialists can perform field replica service (Field Metallography Replication, or FMR) using acetate film or silicone based resin based on ASTM E 1351. Replicas can be viewed and analyzed by optical microscope or scanning electron microscope in the lab.
The followings micrographs are some examples we took from the field at 100x or 400 magnification this year.
The normal procedure is as follows: portable grinder and polisher are used for on-site sample preparation. Then a field microscope is used to examine the quality of the polish. After a satisfactory finishing is achieved, a compatible chemical etchant is used to reveal the microstructure of the polished spot. If desired, electrochemical etching can also be performed. Finally digital images can be taken by a portable microscope with various magnification from 20x, 100x, 200x to 400x magnifications. If needed, we can even take micrographs at 1000x magnification through proprierty techniques, which nobody else in the world have tried or achieved.
If even greater resolution is required, PMI specialists can perform field replica service (Field Metallography Replication, or FMR) using acetate film or silicone based resin based on ASTM E 1351. Replicas can be viewed and analyzed by optical microscope or scanning electron microscope in the lab.
The followings micrographs are some examples we took from the field at 100x or 400 magnification this year.
