Archives pour la catégorie Publications

Damage mechanism and prevention of heavy-haul railway rail

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A new interesting paper in  » Engineering Failure Analysis »  of december 2013 published on ScienceDirect.com.

The objective of this paper was to investigate wear and damage behavior of heavy-haul railway rail.

More at : Investigation on the damage mech………

Failure analysis of copper tube

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A new interesting paper in « Engineering Failure Analysis » published on ScienceDirect.com. This paper reports the failure analysis of a leaked copper tube used in a refrigerating plant for carrying polyol ester oil for lubrication and cooling of compressor bearings. Failure had occurred at the bent region of the tube in the form of a wide diametric crack.

More information : Failure analysis of copper tube used in a refrigerating plant.

Stress corrosion cracking in 316L stainless steel

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

There were three consecutive occurrences of bellows failure in a particular pressure safety valve (PSV) of a petroleum refinery within a time span of one week. The bellows were made of 316L grade austenitic stainless steel, and the PSV was mounted on one of the vessels of vacuum gas oil service in a hydrocracker unit. Metallurgical analysis of the failed bellows revealed that the failure had occurred by stress corrosion cracking (SCC). This paper brings out the detail of investigation carried out.

Validation of F-16 Wing Attachment Fitting bolts

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A new paper in  « Engineering Failure Analysis » published on ScienceDirect.com.

During a modification programme, the Wing Attachment Fitting (WAF) cadmium-plated steel bolt assemblies from 33 F-16 aircraft were cleaned in a non-approved chemical solution, a paint stripper. This removed much of the cadmium plating, leading to in-service superficial rusting of some bolt ends and nuts. The OEM and chemical manufacturer became concerned about possible hydrogen embrittlement of the bolts owing to exposure to the paint stripper. This paper brings out the detail of investigation carried out.

Assessment of a gouge and dent defect in a pipeline

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This paper pubished in Engineering Failure Analysis, deals with A37 steel pipelines containing a gouge and dent defect. The influence of the dent depth on the burst pressure of pipelines is evaluated for a given geometry of the gouge. Experimental burst tests are performed and finite element analysis is used in order to compare the numerical and experimental results. Experimental results showed that a combined gouge and dent defect does not reduce the burst pressure of A37 steel pipelines. These results contradict established research conclusions and the bulk of the literature on the subject. A combined criterion based on volumetric method and stress triaxiality is proposed for assessment of pipelines containing a gouge and dent defect.

Analysis of notch effect in the apparent fracture toughness and fracture micromechanisms

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This paper, reported by Sciencedirect.com, presents an analysis of the notch effect on two ferritic-pearlitic steels operating within their corresponding lower shelf, and develops an experimental programme, composed of 28 CT characterisation specimens and 72 CT validation specimens, together with finite elements analysis with the aim of validating the apparent fracture toughness predictions provided by the Theory of Critical Distances. The results have shown how this theory provides reasonable predictions of the apparent fracture toughness of the material .

The research is completed with the analysis of the evolution of fracture micromechanisms when the notch radius increases, revealing a direct relation between this evolution and the apparent fracture toughness observations.

Failure analysis of a martensitic stainless steel roll

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Sciencedirect.com report an article published in « Engineering Failure Analysis » : the failure analysis of a martensitic stainless steel (CA-15M) roll manufactured by centrifugal casting and used in cast glass rolling was carried out. The crack propagation began in the internal surface of the roll. Tensile thermal stresses in the internal surface of the roll associated with microstructural embrittlement (network of interfacial carbide and porosities) are thought to be the main causes for the premature failure of the roll. Finally, materials selection was performed to replace the CA-15M stainless steel with another class of stainless steel for centrifugal casting.

Fragilisation par le zinc liquide des aciers haute resistance

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MATEC Web of Conferences signale une étude présentant les investigations menées sur la fragilisation par le zinc liquide d’un acier électro-zingué. Elle a permis de caractériser la perte de ductilité en traction d’un acier galvanise causée par la FML (fragilisation par les Métaux Liquides). Le lien entre fragilisation, mouillage intergranulaire et propagation de fissure a été établi.

Cette étude a été présentée lors des journées annuelles de la SF2M 2013, les 29-31 octobre 2013, à l’ Ecole Centrale de Lille.

Cracking of an austenitic stainless steel lance pipe

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Kiln of a lime plant, a part of an integrated steel plant, converts limestone (CaCO3) into lime (CaO) by heating at a temperature of around 900 °C using coke oven gas as a fuel. Coke oven gas is a by-product of the coke plant, which contains mainly hydro-carbons. The coke oven gas is lanced into the kiln through a number of pipes attached to the kiln. The lance pipes are cracking prematurely within 6 months of their service against an expected service life of 3 years.  The analysis of cracking of the lance pipe is presented in this article. It will be published in Engineering Failure Analysis in December 2013.

More information at : Cracking of an austenitic stainless steel lance pipe in a lime calcining plant.

Un cours sur la Mécanique de la rupture

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La mécanique de la rupture a été introduite par Griffith vers 1920. L’objectif de la mécanique de la rupture est de caractériser le comportement à la fissuration des structures à l’aide de paramètres quantifiables au sens de l’ingénieur, notamment le champ de contraintes, la taille de la fissure et la résistance à la fissuration du matériau.

J’ai trouvé ce cours de l’Ecole des Mines de Douai mis en ligne en octobre 2010, il vous montrera que la  compréhension des phénomènes physiques à la base des endommagements et de la rupture est fondamentale pour choisir les méthodes appropriées d’analyses de défaillances ou de dimensionnement de pièces mécaniques.