Field Metallographic Replication (FMR) to Analyze Microstructure In-Situ

FMR-of-crack-in-steel.jpg

Field metallographic replication of crack in steel found by G2MT Labs FMR evaluation team

Field metallographic replication (FMR) is one of the most cost-effective methods for metallurgical evaluation needed for run-repair-or-replace decision-making on large components or systems. FMR analysis allows you to bring the metallography laboratory to your field sites for assessment of high-temperature hydrogen attack (HTHA), stress corrosion cracking, creep damage, void formation, and other forms of damage that are only visible on a microscopic level. Our field metallographic replication technicians are among the best in the business; we take the time and care to achieve the extremely high-quality imaging necessary for good FMR analysis. The results are used to determine the nature and extent of defects, flaws, cracking, and other problems that are invisible to most other techniques.

What is Field Metallography?

Field metallographic replication testing, FMR, is a common type of non-destructive testing that has been used for decades. The practices we use for FMR are described in the ASTM E 1351 specification for ‘Production and Evaluation of Field Metallographic Replicas’. The FMR procedure is best for in-situ analysis of the microstructure and other metallurgical features of steels and other metals when removal of samples for laboratory analysis is impractical or impossible. Our FMR inspection team of technicians and scientists can come to your site, often the same day in the U.S., to perform field metallographic replication.

In some cases, further risk-based integrity analysis is used to evaluate the integrity of materials and establish practices for continued safe operation and maintenance. FMR is performed by using similar practices to those employed for standard laboratory metallography; the catch is that FMR is often performed in tightly enclosed spaces and requires skilled technicians to produce high-qualify images.

Field Metallographic Replication and Brinnell Hardness Testing was performed to evaluate the effect of fire damage on a pipeline by G2MT Labs

Field Metallographic Replication and Brinnell Hardness Testing was performed to evaluate the effect of fire damage on this pipeline

How is field metallography performed in the field?

The FMR practice follows the same procedure as standard metallography: the surface is prepared with grinding and then polishing with finer grits of abrasive until a diamond or silica cloth polish is used to obtain a mirror-like finish with no visible scratches. FMR measurements are performed using portable high-magnification microscopes to assess the metal surface, microstructure, defects, and other features, and images are taken with a connected digital camera.

In some cases, a sample removal tool is used to carefully remove specimens for laboratory testing without changing the properties that are measured in the laboratory. In that case, optical and/or electron microscopy are performed to provide further insight into the materials properties and any specific areas of concern (for example: microstructure changes, aging, corrosion, precipitate formation, and other defects).

Why use FMR Analysis?

The ability to perform field metallography on-site can be extremely valuable in circumstances when samples cannot be removed, when rapid testing is needed, or during shut-downs. The features observed during field metallographic replication are the same as those observed by laboratory metallography and can successfully be used to identify a wide variety of changes or defects that can affect components in critical applications.

FMR is widely used in:

  • process piping,
  • high-pressure piping,
  • fire damage assessment,
  • pressure vessels,
  • suspected HTHA damage, and
  • other areas where sample removal is not easy.

In some cases, FMR is also used as a complement to other nondestructive tests (e.g. ultrasound, eddy current, dye penetrant, and acoustic emission) to confirm the measurements and identify more details of the observed flaws or defects [1].  We look forward to answering any questions you may have and helping with your FMR needs!