[TheForge] Spring steel (and other) breaking in mild acid

[peter fels]

That's a complete mystery to me!
Be very interested to hear what our experts say Clyde.


On Aug 25, 2011, at 5:48 PM, Clyde Wynia wrote:

> 
> I make part of a piece of sculpture that serves as a back for a cat. I take
> a piece of 3/8" rod about 18" long and bend it into not quite a semi circle.
> I then take a piece of garage door spring about 2" diameter and slip it over
> the U shaped rod. This is just a very mild bend around the rod. I do not
> weld the spring in any place, only the rod is welded to the legs.
> 
> As I do with hundreds of other pieces, I put the piece, not hot, into a
> mild, 10 to 1, bath of water and muriatic acid to remove the mill scale,
> rust etc. The solution by this time of year is very weak. However, when I
> remove the piece the spring is broken into 1 to 4 pieces.
> 
> This also happens with bearing races, 5" to 7" diameter that have been put
> into the acid. The cross crack does not occur near a weld and is not put in
> the solution hot.
> 
> So what is happening to cause these breaks in this very mild acid solution?
> 
> Clyde Wynia
> 
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