Archives du mot-clef Acier

Low hardness on bearing race

Publié le par
Répondre

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.

Read more

Failure analysis of a nose landing gear fork

Publié le par
Répondre

2017-02-02_09h26_14This paper presents a detailed analysis of a nose landing gear failure. The developed work comes following an accident occurred in which the nose of the landing gear’s fork of a light aircraft bent during landing. Nose gear failures are a high concern in the aviation industry. According to Federal Aviation Administration, in average 55% of aircraft failures occur during takeoff and landing while the remaining occurs during flight

Read more ….

Vintage-La rupture en service des assemblages vissés

Publié le par
Répondre

Vintage assemblages vissesLes experts en analyse de défaillances du Cetim ont réalisé courant 1988 une étude statistique de 139 cas de ruptures d’assemblages vissés. Les résultats ont montré que pour les deux tiers des cas traités, 53 % des cas de rupture est dû à un phénomène de fissuration progressive et 47 % correspond à des ruptures brutales. Pour le tiers restant, plusieurs causes  conjuguées étaient à l’origine des défaillances.

telecharger le doc

 

Cracking of underground welded steel pipes caused by HAZ sensitization

Publié le par
Répondre

An article on case study, published in « Case Studies in Engineering Failure Analysis« , on january 2013.

Low alloy steel welded pipes buried in the ground were sent for failure analysis investigation. Failure of steel pipes was not caused by tensile ductile overload but resulted from low ductility fracture in the area of the weld, which also contains multiple intergranular secondary cracks. The failure is most probably attributed to intergranular cracking initiating from the outer surface in the weld heat affected zone and propagated through the wall thickness.

Read more ….

Metallurgical investigation of different causes of center bursting led to wire breakage during production

Publié le par
Répondre

2016-11-03_09h22_22A case study published in « Case Studies in Engineering Failure Analysis« , on january 2013.

Central bursting cause problem as it is hard to detect by means of surface check. In this paper, three broken wires which failed during production were investigated. In first two wires breakage took place due to formation of hard and brittle phase. In third case failure took place due to inappropriate drawing operations.

Read more

Grooving corrosion of seam welded oil pipelines

Publié le par
Répondre

A interesting paper in « Case study in Engineering Failure Analysis«  published on ScienceDirect.com.

24″ pipeline carrying oil was failed in the form of longitudinal crack at the 6 O’clock position resulting in oil spill. The failed pipe was investigated to reveal the main cause of its failure. Cracks were originated from weld defected sites, initiated by grooving corrosion, propagated by inertia at the normal designed pressure condition, and stopped when stress relief is attained.

Read more

Cas Concrets de ruptures brutales

Publié le par
Répondre

Avatar Cas ConcretsCinq cas d’analyses de ruptures brutales survenues en cours de fabrication, en essai et en service ont été réalisés au Cetim. Elles ont fait l’objet de fiches d’analyse de défaillance publiées en 1981 et 1982 dans la revue Cetim-information. Toujours d’actualité, retrouvez les dans la Mécatech du Cetim.

telecharger le doc

EFFECT ANALYSIS OF AN ARC-STRIKE-INDUCED DEFECT ON THE FAILURE OF A POST-TENSIONED THREADBAR

Publié le par
Répondre

A new article available online 10 November 2015 in « Case Studies in Engineering Failure Analysis ».

A temporary threadbar used for precast segmental construction broke during the post-tensioning stage before reaching the service load. Failure analysis showed that the premature failure of the bar was due to the presence of an arc strike. The arc strike effects on the material and threadbar integrity are studied. Read more….

 

Corrosion of Welded Joint in Alloy Steel Pipe

Publié le par
Répondre

2015-11-15_10h33_54An interesting article published on 4 November 2015 in the International Journal of ELECTROCHEMICAL SCIENCE.

In this paper an investigation on corrosion behaviour of welded joints was performed to facilitate determination the causes of preferential degradation by corrosion of the welded metal (WM) and the heat affected zone (HAZ), in a welded pipeline of grade ASTM A355P5, used in a petrochemical plant as transfer line between a thermal cracking heater and a column which are part of an atmospheric distillation and vacuum (DAV) unit. It was found that the corrosion of the weld analyzed in this research has resulted due to its dendritic structure (pearlite, ferrite, complex carbide, bainite and martensite in localized areas), which reveals the lack of post welding heat treatment (PWHT). Read more …..

 

Évaluer l’intégrité et la réparabilité

Publié le par
Répondre

Stir_Img_DetailReference

La Société tunisienne des industries du raffinage (Stir) possède, entre autres, une sphère de stockage de 4000 m3 qui a présenté des défauts diamétralement opposés au niveau d’une soudure circonférentielle basse. La Stir a souhaité évaluer l’intégrité et la réparabilité de l’équipement et se prononcer sur sa requalification périodique. Le Cetim est intervenu à la demande du Centre technique des industries mécaniques et électriques de Tunisie (Cetime) afin d’effectuer un diagnostic global sur trois sphères de gaz. Un partenariat exemplaire !

Pour en savoir plus, lire le document.

Les compétences du Cetim s’expriment à travers sa capacité à maîtriser l’ensemble des technologies mécaniques. Les cas qui sont présentées ici exposent des exemples de réalisations menées pour ses clients tant à titre collectif qu’à titre individuel. Elles témoignent de la capacité du Cetim à proposer une offre globale et personnalisée de prestations autant pour les grands donneurs d’ordre que pour les petites entreprises.