IIS SERVICE performs in-site non destructive metallographic examination through replicas. This type of non destructive investigation is generally required to examine microstructures of materials (plates, pipes, forgings, castings) or on welded joints to examine base metal, weld metal and heat affected zone microstructures.
This test is able to reveal microstructural damage or ageing phenomena (brittle phase precipitation, creep damage) or to interpretate the nature of cracking phenomena (fatigue, corrosion, hydrogen attack, etc.). The investigation may have several purposes: to ascertain microstructural damage due to overheating, burning or fire; assessment of ageing phenomena during service time and residual life estimation; pre-service inspection for microstructure recording at the start-up of service time for comparison during further inspection
>> The technique
- Elimination of surface non metallic layers (oxidation, paint, etc.) by grinding
- Gross polishing by abrasive paper
- Fine polishing by diamond paste
- Chemical etching to reveal different metallographic phases and microstructures
- Application on the surface of cellulose acethate film to replicate the microstructure
- Removal of cellulose film to be observed
- Observation of the replica with optical or scanning electron microscope.
IIS SERVICE has a longstanding experience in investigation by replica, both in extraction technique and in interpretation. Our technicians and engineers are able to intervene in workshops, plant or worksite for carrying out the examination and providing prompt interpretation.