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

[Kim George]

It could be the fracturing of stress cracks. The acid eats the surface
allowing the cracks to separate.Ever try forging an old coil spring of
a car? same thing.

On 8/25/11, peter fels <artgawk at thegrid.net> wrote:
> 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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-- 
Kim George

"Why for you try to bury me in cold,cold ground?"
     Taz