Failure Analysis of a Polymer Centrifugal Impeller

An other new case study of failure analysis had been published in october 2015 in Case Studies in Engineering Failure Analysis.

A failure analysis investigation was performed on a fractured polymer impeller used in a respiratory blower. A radial split down the impeller center was observed, with symmetric fracture faces about the impeller bore. The brittle fracture morphology and defects within the impeller bore suggest that premature failure occurred because of multiple interacting factors including: intermittently high centrifugal velocities, imbalance bore and shaft conditions, defects within the bore caused by machining, and stress concentrations along the circumference of the impeller lip.

Read more at : Failure Analysis of a Polymer Centrifugal Impeller.

Failure Analysis of Work Rolls of a Thin Hot Strip Mill

A new interesting article published in « Case Studies in Engineering Failure Analysis »

In hot rolling mills, premature failure of rolls is a major concern as it adversely affects the mill operation and as well as production. Analysis of failed roll materials and actual rolling conditions in service are therefore necessary to understand the roll failure mechanism and thereby improve the wear resistance and extend the service life of rolls.

This work describes two different types of roll failure cases and their analysis which was carried out using destructive as well as non-destructive testing techniques (NDT). The cases are as follows:

(a)

Case I: Enhanced ICDP Bottom roll of fifth stand (F#5) which failed from the neck portion.

(b)

Case II: Analysis of sub-surface defect of ICDP rolls of the last stand (F#6

Lire la suite

 

Failure analysis of work rolls of a thin hot strip mill

A new case study of failure analysis published on Sciencedirect.com

In hot rolling mills, premature failure of rolls is a major concern as it adversely affects the mill operation as well as production. Analysis of failed roll materials and actual rolling conditions in service are therefore necessary to understand the roll failure mechanism and thereby improve the wear resistance and extend the service life of rolls.

The hot strip mill referred here consists of six stands wherein high chromium (Hi-Cr) iron rolls and Indefinite Chilled Double Poured (ICDP) cast iron rolls are being used for finishing rolling of the strips in the last two stands. The thin strip mill produces strips in the thickness range of 1.0–12.7 mm. This work describes two different types of roll failure cases and their analysis which was carried out using destructive as well as non-destructive testing techniques (NDT).

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Brittle fracture of a grade E cast steel knuckle

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

Acceder article

Failure Analysis of Automobile Redirector

The failure reasons of the valve shell from automobile redirector were investigated by metallography, fractography and mechanical property test. The result showed that continuous Si-phase with dentritic shape due to the improper solution-aged process and excessive Fe element remained due to the ineffective modification treatment were the main reasons of components’ brittle fracture.

Plus d’info : http://www.scientific.net/AMR.415-417.2146

 

Catastrophic failure of marine AC generator core

www.dtbtest.com/PDFs/ac-generator-core-failure.pdf

Description : Catastrophic failure of marine AC generator core
Problem : Co-base alloy generator core failed after overheat event
Analysis : Cobalt alloy core became highly brittle after slow cooling
from overheat condition. Brittleness was due to ordering transformation.
Resolution & Recommendations :
Use temperature sensors to ensure thermal excursions
stay below the order-disorder transition temperature.
Fiche analyse défaillance DAYTON T. BROWN METALLURGICAL LABORATORY