Anti-corrosion techniques could double the life of steel
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Anti-corrosion techniques that could double the life of steel have been developed at Hertfordshire University.
The techniques, which could reduce steel corrosion rates by 50 per cent, involve passing an electric current through a material or applying an electromagnetic field to a material for two to three minutes.
Andreas Chrysanthou, leader of the Materials Research group at Hertfordshire University, said: ‘The work so far is showing that there is some kind of reduction in the residual stresses.’
These stresses form in a material and create defects, which alter the electrochemical behaviour of a material from one side to the other.
‘Through using these new techniques we’re hoping to produce a more uniform structure by manipulating the composition of the material at a microstructure level,’ said Chrysanthou. ‘Our research suggests this will then reduce the corrosion levels.’
The team has so far completed seven experiments but only one of these has been conducted using the electromagnetic field technique. However, Chrysanthou claims that the end result is the same for both techniques.
Douglas Michaels, technical secretary from the Institute of Corrosion, said: ‘The problem I have is seeing how the electromagnetic field mechanism will work. There is nothing inherently obvious about how very strong electromagnetic fields will affect the structure of the steel.
‘It is possible that they induce some heating effect, which grows the air-formed oxide. This might cause the oxide film to take longer to break down. However, this would not be a lasting effect.’
Chrysanthou countered this by stating the work done so far suggests the techniques have an affect on the dislocation density — effectively reducing the residual stresses on the material and these are the same stresses that can actually lead to more corrosion.
’It’s early days yet but this is what we suspect at the moment. I have some scepticism about it myself,’ said Chrysanthou. ‘We are doing the work at the moment to better understand the mechanisms.’
The tests so far have been on sheet material mainly varying from 0.8mm to 1.5mm in thickness, with one of the experiments being done on a cylindrical bar with a diameter of 10mm.
Chrysanthou said the team would be inviting industry to seminars with the aim of getting them to invest in the technologies and fit their own rigs.
The Institute of Corrosion claims that it costs the UK 3–4% of the GNP each year, which equates to about £30–40bn.
A recent grant of €278,680 from Marie Curie International Incoming Fellowship has been awarded to the project and will be put towards carrying out further research.
Readers' comments (5)
Denis Halls | 13 Oct 2011 6:31 am
I find it difficult to believe we are talking new undiscovered technology.The effects of elecromagnetic fields and electric current passed through materials is not new and based against the normal timescale of material corrosion and the quality of modern externally applied protection available, I believe this "new" technology has its limitations.
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Graham Cannon | 13 Oct 2011 10:56 am
Interesting if correct. Do the researchers believe this could be applied to the suspension bridges of the world to delay the deterioration of the snapping strands in the support cables ?
Would the current/heating, affect the basic tempering of suspension bridge cables ?
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Editor's comments | 13 Oct 2011 10:56 am
The technique has only been applied to very thin sheets of steel or steel tubes with a diameter much less than the cables used on suspension bridges.
I do not believe the tempering is affected in any significant way.
Malcolm | 15 Oct 2011 6:41 pm
If we extend the life of a car body wouldn't we need to introduce a scrappage scheme to get them off the road and keep the manufacturer's profits up?
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Peter Clark | 18 Oct 2011 0:16 am
As a metallurgist and corrosion engineer for over 60 years it sounds too good to be true. The only way I can see it re-ordering structure and stresses is by using heat as well as magnetic fields. I wish it well but would like to see some convincing research details and theory. Until then I wil remain very sceptical.
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Davey of Cornwall | 19 Oct 2011 2:52 pm
I used to work as a machine repair technician at a car factory which made budget quality cars. The body panels were sometimes pre-rusted on the journey from the steel works. After the panels were welded into a body-shell the rust was cleaned off with some kind of acid. After this the cleaned shell went into a phosphating tank and a high current and voltage was used to phosphate the metal. Unfortunately the box members such as sills behave as a Faraday Cage so the reaction in there is negligible. After the shell is washed and dried it gets painted -by spray. Once again very little effect (paint) gets inside the box members. Quality cars are built from Zintec, another way is to use a full-body-paint-dip. Not rocket science is it?
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