Engineering the Future
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COMPONENT FAILURE MUSEUM

The main sections of the museum are listed below;

Metal Fatigue
Manufacturing Faults
Bicycle Components
Corrosion
Polymers
Composite Materials

Tools of the trade, some ways to investigate problems;
Photoelasticity
Dye penetrant testing

Glossary
of materials engineering terms

 

Corrosion failures.

Corrosion

A phenomenon which results from chemical degradation of metals and alloys due to reaction with agents in the service environment, e.g. the rusting of steel in moist air. May take the form of uniform attack over the whole surface or as highly localised pitting.

For further information on the phenomena of corrosion follow this link to
an explanation of corrosion,
or select links below for stories of specific failures

Click on pictures below for full size image.

 

The deep drawn brass cup on the right shows stress corrosion cracking under the influence of the residual manufacturing stresses and a mildly corrosive environment. The cup on the left has been annealed before putting it into service which solves the problem.

 

This is another example of stress corrosion cracking where residual stress, a susceptible microstructure and a mildly corrosive atmosphere have caused rapid cracking in this thick walled brass tube.

 

 Many brass plumbing fittings have electrochemical cells between their constituent phases. This leads to rapid corrosion cracks which have a coppery colour due to dezincification where the zinc content is leached out.

 

 The current trend for aluminium vehicles is not without problems. This aluminium alloy chassis member shows very advanced corrosion due to contact with road salt from gritting operations or use in coastal / beach regions.

 

 This bronze propeller blade appears to have suffered corrosion. However it is not a chemical attack. Closer examination reveals that it is associated with the leading edge of the blade.

<Further information>

Failure of aluminium mountain bike seatpost

<Further information>

This polished aluminium rim was left over Christmas with road salt and mud on the rim. Galvanic corrosion has started between the chromium plated brass spoke nipple and the aluminium rim. 

 

 Galavanic corrosion can be even worse underneath the tyre in bicycles used all winter. Here the corrosion is so advanced it has penetrated the rim thickness.

 

 

17/12/01 ed:AG

 
 
© 2005 Materials Engineering - Page last modified 18-Dec-2007