Delayed information due to residual stress
Delayed information due to residual stress
(OP)
Is there anyone who can shed some light on the subject of residual stress and delayed plastic deformation under static condition? I am of the opinion that the distribution of any residual stress in a cast or welded construction is stable, and that plastic deformation can only occur when stress due to externally applied mechanical or thermal load, together with the internal stress, exceed the yield stress causing plastic deformation.
However, some claim that this can also occur in a short period after casting or welding. This is supported by their claim that large cast parts such as engine blocks are stored for a year before further machining, just to make sure that the internal stress level is levelled.
Thanks for any input, and in particular literature references are very welcome.
However, some claim that this can also occur in a short period after casting or welding. This is supported by their claim that large cast parts such as engine blocks are stored for a year before further machining, just to make sure that the internal stress level is levelled.
Thanks for any input, and in particular literature references are very welcome.





RE: Delayed information due to residual stress
Now would be a good time to introduce you to the search feature above, which is a powerful tool. Just typing in residual stress results in over 100 posts that you can review. You can refine the search based on key words. The topic of residual stress distribution, magnitude, measurement and reduction has been discussed in previous posts.
RE: Delayed information due to residual stress
And of course I should have typed delayed DEFORMATION instead of delayed INFORMATION in the header.
RE: Delayed information due to residual stress
RE: Delayed information due to residual stress
The above can be explained by self relieving or relaxation of residual stresses over time within the material and not external stresses.
RE: Delayed information due to residual stress
RE: Delayed information due to residual stress
RE: Delayed information due to residual stress
I believe this is a combination of stress relaxation/redistribution and is a result of both plastic compressive and tesnile strains being introduced during the straightening. Becasue of the Bauschinger effect, the yeild stress in areas that have had a plastic tensile strain is different from those that have had a plastic compressive strain. The residual stress levels are at the yield stress in these areas, but since the yeild stress is not constant, the residual stress levels are not constant. Add to this some thermal expansion and contraction, they no longer balance and you get movement.
I would guess it would be difficult to find much in the literature on this since it is very difficult to quantify, which makes an anaylitical analysis tough. Since, with pipe anyway, you are looking at L/d ratios of aorund 100 or so, just quantifying straightness is hard to do.
rp
RE: Delayed information due to residual stress
RE: Delayed information due to residual stress
Pretty interesting.
Fe
RE: Delayed information due to residual stress
That should have read "Take a look at this study".
Fe
RE: Delayed information due to residual stress
RE: Delayed information due to residual stress
I may have something on steel. But, I doubt welded.
Fe