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Expertises

The target is to perform the investigations need to determine the causes of a failure (anormal wearing, breaking, cracking, corrosion…)

CRITT MATÉRIAUX INNOVATION provides you its staff’s expertise and all its testing and analysis means for:

– Identify nature and origin of the failure

– Establish the likely scenarios that caused its occurrence

– Support you for your research of solutions.

Find below some typical examples which CRITT MATÉRIAUX INNOVATION can perform.

Expertises

The target is to perform the investigations need to determine the causes of a failure (anormal wearing, breaking, cracking, corrosion…)

CRITT MATÉRIAUX INNOVATION provides you its staff’s expertise and all its testing and analysis means for:

– Identify nature and origin of the failure

– Establish the likely scenarios that caused its occurrence

– Support you for your research of solutions.

Find below some typical examples which CRITT MATÉRIAUX INNOVATION can perform.

Expertise of a femoral stem after breaking

Micrographic examinations
by binocular magnifier

View of the fracture facies. Demonstration of propagation lines typical of fatigue breakage.

View at the fracture initiation area: spoiled surface due to a fretting-corrosion phenomena (in the yellow ellipse).

Examination
by optical microscope

View of the fracture area, without etching: presence of oxides due to fretting-corrosion (grey areas)

View of microstructure after etching: this one is correct, free of contamination and therefore it’s not the cause of the breakage.

Therefore we can conclude that the breakage is caused by a fretting-corrosion phenomena (oxidation due to micro movements between two assembled parts) generating oxides constituing the beginning of a fatigue phenomena (slow propagation of a microcracking).

Expertise of a stainless steel pipe, corroded inside

Examination
by binocular magnifier

General view inside the pipe, showing many corrosion pitting.

View with higher magnification of a corrosion pitting.

Examination
by optical microscope

Cross-sectionnal view, without etching, highlighting cavity due to corrosion. We see too a good surface finish on other areas and free of non-metallic inclusions.

Core cross-sectionnal view, with acid etching, highlighting metallographic structure type austenitic macle. It appears very much healthy.



Examination by scanning electron microscope (SEM) coupled with EDS

SEM view of a pitted area (dark area on the right of picture), where the next analysises will be focus.

EDS spectrum of chemical elements present in the area. Add to the stainless steel constitutive elements (Fe, Cr, Ni), we observe the anormal presence of chlorine and traces of sulfur.

Highlighting (yellow area) of a high concentration of chlorine focused on the corrosion pitting.

Highlighting (blue area) of a high concentration of sulfur focused on an other area of the corrosion pitting.

We can deduct from this expertise that the part does not present issue which could promote the corrosion and that the observed pitting was due by exogen input of chlorine and sulfur, probably coming, according with use of this pipe, from detergent agents residus.

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