Archives du mot-clef analyse de défaillances

Weld failure analysis of 2205 duplex stainless steel nozzle

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A publication in « Case Studies in Engineering Failure Analysiss, october 2014.

Failure analyses of weld joint between the nozzle and the head of the reactor made of 2205 duplex stainless steel was performed by optical microscopy (OM) and scanning electron microscopy (SEM). Cracks were found in HAZ of the weld. The depth of the cracks is equal to the thickness of the inner weld. Localized uneven distribution of ferrite/austenite with 80-90% ferrite in weld is found. Results show that the cracks occurred along columnar granular with cleavage fracture. Poor weld process probably results in these cracks.

Source : Case Studies in Engineering Failure Analysis

Cas Concrets – Des ruptures brutales

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Avatar Cas ConcretsQuatre fiches de cas d’analyses de défaillances survenues en service : une pièce de jonction en acier, un extincteur à gaz en alliage d’aluminium, une pièce d’attelage en acier mécano soudé et un essieu directeur de chariot élévateur, peuvent être consultées dans la Mécatech du Cetim.

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Abrasive Wear Failure Analysis of Tungsten Carbide Hard facing on Carbon Steel Blade

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This content has been downloaded from IOPscience, Series: Materials Science and Engineering 165 (2017),

This study investigate the abrasive wear failure of tungsten carbide hardfacing on continuous digester (CD) blade (carbon steel) in an environment of sulphuric acid and ilmenite ore mixture. Comparison being made on the hardness, thickness and microstructural of the hardfacing between unworn and 3 months old worn blade on few locations around the blade. The cross sections of the blade revealed non-uniform coverage of the hardfacing on the blade for both worn and unworn blade. The edge of the blade has the least amount of hardfacing thickness which with time acts as the point of failure during the wear process. The hardness obtained from both the unworn and worn samples are around 25% lower from the hardfacing electrode manufacturer’s hardness specification. Microstructural micrograph analysis of the hardfacing reveale

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Failure analysis of a bridge crane shaft

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A paper published in « Case Studies in Engineering Failure Analysis » on april 2014.

Failure analysis of a shaft used in a bridge crane has been carried out. The shaft fractured in the keyway with evidence of fatigue. The geometry of the keyway also promoted the initiation crack because the width and height were erroneously designed. It was concluded that all these factors produced fatigue failure.

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Brittle fracture of a grade E cast steel knuckle

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This paper was published in « Case Studies in Engineering Failure Analysis » on April 2014. It investigated the brittle fracture mechanism of a grade E cast steel knuckle that is one of the key components of the coupler for railway wagon.

As a result, it can be inferred that under an impact load that did not exceed material fracture limit, the micro-cracks initiated from weld repair zone propagated rapidly into the inner matrix by continuously fracturing the dendrites along shrinkage porosity regions until the knuckle failed instantly.

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4 Cas Concrets de ruptures

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Avatar Cas ConcretsQuatre cas d’analyses de défaillances par ruptures survenues sur des organes de machines de divers horizons : un tirant de palier, un arbre de roue, un corps de piston et un corps d’amortisseur de tampon de wagon ferroviaire.

Ces quatre fiches d’analyse de défaillances avaient été publiées en avril 1987 dans le numéro 100 de la revue Cetim-information. Elles sont toujours d’actualité.

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Fatigue fracture of cutter blade made of high-speed steel

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An interesting  paper in « Case study in Engineering Failure Analysis » published on ScienceDirect.com. This paper presents the failure analysis of broken blade of the cutter Ku 500VX. The damage of the blade was caused by changes of the structure (formation of the brittle micro dendritic structure) that occurred during manual electric engraving process when the material was heated till its melting point. As a results the stresses occurred in surface what provided to micro cracking and to propagate the fatigue fracture. The origin of this fatigue fracture was in the place where the inscription was made.

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Low hardness on bearing race

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An interesting paper in « Case studies in Engineering Failure Analysis » published on ScienceDirect.com.

Presence of decarburization on rolled bar coupled with out of square forging can lead to the presence of decarburized layer on one of the faces of a bearing race. This decarburized layer gives rise to low hardness on the face of the race. A series of examinations including micro-structural and macroscopic examinations on the defective samples revealed out of square forging as a root cause for the presence of the decarburized layer on a part of the one of the faces of a bearing outer race. This paper brings out the detail of investigation carried out.

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Evaluating the coupled thermo-mechanical stresses for an aluminum alloy piston used in a gasoline engine

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2017-02-02_09h44_08An article published in « The Journal of Engine Research » Vol. 42 (Spring 2016).

In the modern engines with higher compression ratios, severe pressures and
non-uniform heating up is occurred for the engine parts. The piston as the
most critical part among all automotive components has been the subject of
numerous studies on calculation of temperature distribution, but thermal
stress analyses are limited. In this study, the piston of gasoline engine XU7
which is widespread in Iran transport section is considered for thermomechanical
investigation.

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Engrenages : les vertus du grenaillage

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2017-01-19_09h32_56Comment améliorer la résistance à la fatigue des engrenages ? Ce nouvel ouvrage de la collection Performances du Cetim explore les réponses proposées dans la littérature et les soumet à l’épreuve des faits ! Des études ont d’ores et déjà montré que le grenaillage appliqué aux engrenages influence de façon notable le comportement en fatigue de flexion. Mais qu’en est-il pour la fatigue de contact ? L’ouvrage, intitulé « Influence du grenaillage sur la tenue en fatigue de contact » (9Q178) répond à cette question.

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