Investigation on brittle fracture mechanism of a grade E cast steel knuckle

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

This paper 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. The fracture morphology mainly shows the characteristic of cleavage, quasi-cleavage fracture as well as a little ductile fracture, so the failure of the knuckle can be attributed to brittle fracture distinctly. Moreover, a welding repair area with high hardness is also found in the fracture region, which might initiate micro-cracks on the surface of the knuckle. 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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ESI lance une nouvelle version de SYSTUS 2017 dédiée au secteur de l’énergie

ESI Group (Paris:ESI), pionnier et principal fournisseur mondial de logiciels et services de Prototypage Virtuel pour les industries manufacturières, annonce la sortie de la dernière version de SYSTUS, solution logicielle éprouvée pour la conception thermomécanique et les analyses réglementaires dans le secteur nucléaire. ESI SYSTUS 2017 apporte de nouvelles fonctionnalités majeures au logiciel, y compris une méthode différentielle innovante (RCCM-MD) pour les analyses règlementaires. Cette version 2017 apporte également des améliorations dans le domaine de la mécanique de rupture avec la méthode X-FEM. Outre ces nouveautés qui concernent le secteur nucléaire, cette nouvelle édition ouvre la voie au traitement de problèmes d’optimisation topologique, notamment dans les secteurs de l’automobile et de l’aéronautique.

Le présent Smart News Release (communiqué de presse intelligent) contient des éléments multimédias. Consultez l’intégralité du communiqué ici : http://www.businesswire.com/news/home/20170803005659/fr/

Brittle fracture of a grade E cast steel knuckle

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.

Read more.

Failure of high-chromium iron roll in compact strip production MILL

2016-12-08_11h16_13A case study published in « Case Studies in Engineering Failure Analysis« , july 2013.

A high chromium (HiCr) iron work roll broke in three pieces in finishing stand 4 in a compact strip production (CSP) mill of a steel company. The paper describes the causes of the roll failure manufactured from high chrome grade steel along with the precautionary measure.

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

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….

 

Failure analysis of 4Cr13 stainless steel linkages in circuit breakers

2016-09-06_15h47_58A case study published in « Case Studies in Engineering Failure Analysis » – April 2016.

In this study, the fracture failure of the 4Cr13 stainless steel linkage components in circuit breakers was studied. The microstructure and morphology of fracture surface were observed by scanning electron microscopy and optical microscopy. A micro-Vickers tester measured the hardness of the components. The tensile strength and strain of the components were determined by a universal testing machine. The results show that fracture failure mode was quasi-cleavage fracture, and some dimples and edges of cleavage were present on the fracture surface.

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Effect analysis of an arc-strike-induced defect on the failure of a post-tensioned threadbar

2016-09-06_15h41_49

An article about a case study published in « Case Studies in Engineering Failure Analysis » – april 2016.

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 considered.

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Failure of Metals I – Brittle and Ductile Fracture

mixteA ne pas manquer de lire sur researchgate.net, trois publications intégrales et récentes sur « La ruptures des métaux » rédigées par André Pineau, A.A. Benzerga et Thomas Pardoen.

La première concerne la rupture ductile et fragile. Il s’agit d’une vue d’ensemble des phénomènes de ruptures sous chargement monotone dans un contexte d’approche globale.

« This is the first of three overviews on failure of metalsHere, brittle and ductile failure under monotonic loadings are addressed  within the context of the local approach to fracture.In this approach, focus is on linking microstructure, physical mechanisms and overall fracture properties….. »

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Cracked Speed Boat Steering Wheel

2015-10-19_13h53_57A Case study published in « Case Studies in Engineering Failures Analysis » of october 2015.

Failure of a cracked steering wheel is studied in this paper. Steering wheel, mounted on a speed boat, had cracks emanating from one of the fastener holes until final fracture occurred.Possible causes of crack occurrence include excessive fastener torque moment, fretting between fastener and hole combined with poor machining that left marks that serve as potential crack initiation points. Obtained results are valuable for predicting fracture behavior of the cracked steering wheel and can be taken as a reference for design and exploitation process of such component.

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Wire breakage of Tyre bead grade

2015-10-18_11h50_39A new case study in « Case Studies in Engineering Failure Analysis » of October 2015.

Tyre bead grade wire is used for tyre making application. The wire is used as reinforcement inside the polymer of tyre. The wire is available in different size/section such as 1.6 mm to 0.80 mm thin Cu coated wire. During tyre making operation at tyre Manufacturer Company, wire failed frequently. In this present study, different broken/defective wire samples were collected from Wire Mill for details investigation of the defect. The analysis revealed that, white layer of surface martensite was formed and it was caused the final breakage of wire. In this study they have also discussed about the possible reason for the formation of such kind of surface martensite (hard-phase).

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