metal shrink? 2

[mielke]

we have a piece of 304SS that is 35 inches long and has a cross section of 1.5" x 5/8". This piece was originally bent with a max gap of 1/8" at the middle and was welded on to 3/8" plate with a tig weld on both sides. once it was on welded on it was ground to flat.

We had two holes one at each end going the long way (35"). once the above process was complete the holes were found to be 1/16"-1/8" short. The piece was straight the hole process so the short value is not a result of it bowing out.

Does it seem plausable that having a bent piece welding it and grinding it flat can shrink 1/16"-1/8"?

 

[desertfox]

hi mielke

Can you load a sketch up I can't quite follow your post it doesn't make sense but I understand your worry over weld shrinkage.
You can estimate shrinkage of welds go to this site:-

http://www.welding-technology-machines.info/welding-distortion/calculation-of-shrinkage.htm

It is possible to have the shrinkage you talk about but there are lots of factors.


desertfox

 

[mielke]

hope this is clearer. The 'A' dimension is the one in question. its the distance between the holes. It ends up being the 1/16-1/8" short.

 

[desertfox]

Hi mielke

A rough rule of thumb for the contraction of a weld is about a (1mm/metre length of weld) so unless its bowed then I can't see the holes being 3mmm out.
One way round the problem is to put the holes in after welding.

desertfox

 

[ornerynorsk]

If your weld is a continuous bead running the full length, yes, you could have shrunk it by that amount. 304 has a lot of movement during welding. We used to struggle with this at a medical products manufacturer I worked for, exclusively 304 stainless weldments. We had to compensate dimensionally on pre-weld components, and straightened nearly everything post-weld.