Stress Relieve Processes?
Stress Relieve Processes?
(OP)
Does anyone have any good recommendations on stress relieve processes? I have a part (2' by 2' by 2') with two wings on it and a bore through both wings (like a giant clevis). Currently we weld the part with tack bars in place then post machine the bore. However, we get significant spring back when we pull out the tack bars. I would like to stress relieve the part before machining, but I don't want to purchase an oven. Does anyone know any other processes I can use. I once herd about vibratory stress relieving but I don't know anything about it.





RE: Stress Relieve Processes?
http://www.meta-lax.com/
RE: Stress Relieve Processes?
RE: Stress Relieve Processes?
RE: Stress Relieve Processes?
The welding process is manual so I'm not sure how repeatable the draw is. Can parts be fixtured accurately to account for weld draw?
My theory is that the welding process is putting stress into my part and the heat/ vibrations caused by machining cause some stress relief...hence the spring back. Any other ideas?
We are looking outside vendors, but I was hoping there were some tricks of the trade out there that I am not aware of.....like this vibration thing. Has anyone used it?
RE: Stress Relieve Processes?
I would follow what you have stated above, use preheat during welding (150 deg F) and avoid stress relief altogether. Look at other ways to fixture for machining.
RE: Stress Relieve Processes?
The residual strain in your welded assembly is due to localized thermal expansion/contraction while the weld joint itself, plus other portions of the structural weld joint not yet fully fused (ie. still tacked), are plastically or elastically displaced.
The least costly remedies (as others have noted) is to employ pre and post heating. You should also work out a process for welding each part of the joint in a specific order, since balancing the heat inputs to the structure will help to minimize thermal strains.
Finally, yes there is such a thing as a vibratory stress relief process. It is generally employed on weldments that are too large to thermally stress relieve. However, personally I've only seen it used with large welded aluminum fixtures, that needed post weld machining. Aluminum weldments tend to have lots of residual strain, probably due to aluminum's high thermal conductivity and the higher amounts of heat input required to fusion weld it. You are using A36 mild steel, which welds beautifully and probably results in a welded structure with the least amount of weld distortion of any material I can think of.
For vibratory stress relief services, check Meta-Lax.
Good luck.
RE: Stress Relieve Processes?
The solution might be as simple as what you related: Cut the braces, allow the strain energy to balance out, and, if need be, reattach those braces needed for the next procedure.
Stress relief with vibration is more effective if resonant vibration is used; see thread: http://www
Another approach is to vibrate during welding, which we should avoid calling stress relieving, or vibratory stress relieving, since it is neither. You certainly do not need a vibratory stress relief system to perform VDW (Vibration During Welding); modest-sized air vibrators, which are both far cheaper and more reliable for this app would be a better choice, might be worth pursuing if the first suggestion (cut and reconnect the braces) doesn't do the trick.
BK