Stress Relief vs. Normalization
Stress Relief vs. Normalization
(OP)
I am welding a 3" thick x 70" OD tube x 48" long. This piece will be machined afer welding on the OD and ID. This is not a code pressure vessel part. Since I want to machine it after it is welded and I don't want it "walking around" during the machining I am debating whether to specify a normalization vs a stress relief post weld heat treatment of the tube.
I would appreciate any thoughts and recommendations.
Thanks.
I would appreciate any thoughts and recommendations.
Thanks.





RE: Stress Relief vs. Normalization
if you normalize you would have to redo all mechanical properties testing after normalization (tensile pulls)
RE: Stress Relief vs. Normalization
As I said this is not a code vessel part. I just want it stablized so that it stays dimensionally stable during the machining process.
I didn't know about having to re-test for the mechanical properties after normalization thanks for that info. I wouldn't be able to re-cert the material material since I don't have any scraps from this material to normalize and re-test.
Does anyone in the audience have experience along these lines? Will a high temp stress relief 1150-1200F for a 3-4 hours accomplish what I want?
RE: Stress Relief vs. Normalization
If you specify a normalization thermal treatment this will alter the bulk properties of the steel, and will void the mechanical properties reported on the MTR.
RE: Stress Relief vs. Normalization
BK
RE: Stress Relief vs. Normalization
What would be the lower transformation temperature of ASTM SA-36 material?
Bkluaba,
I have researched vibratory stress relief in the past. I never could find definitive proof that it worked. There are testimonies and statements but I have never seen hard data such as before and after strain data or residual stress data from strain gages that would prove that it worked.
Thanks for the input though.
Tommy
RE: Stress Relief vs. Normalization
2.25 to 2.5 hours holding time for full pwht
yours may not need to hold quite that long, but while you have it up......
RE: Stress Relief vs. Normalization
About 1330 deg F for this material. I would remain 50 deg F below this temperature, which is where most construction codes settle on 1100 deg F min for subcritical thermal treatment.
RE: Stress Relief vs. Normalization
I really appreciate the input and advice.
Tommy
RE: Stress Relief vs. Normalization
RE: Stress Relief vs. Normalization
RE: Stress Relief vs. Normalization
I tried the "blank" equipment a couple of years ago on a large gear that I was doing a weld repair on. The kindest thing that I can say about it is that I wasn't satisfied. Believe me they make some wonderful claims, but if method really worked as well as they say, I think the ASME would recognize it as an alterantive to thermal stress relieving. If I thought it worked I would try it again and might buy one but I would have to see proof, not claims.
Thanks,
Tommy
RE: Stress Relief vs. Normalization
Look at the website I sited ( www.vsrtechology.net ). Open the link and go to the technical library. Probably the best work that might surprise you is that of Dawson and Moffat. They took numerous samples of 3 different alloys, and succeeded in removing 90% of the stresses initially present, using resonant vibration.
Dawson was at Perkins Engine at the time; Moffat (who sent me a clean, hard copy of this work for inclusion in the VSR Library) was at the U. of Liverpool.
This work was first published in the UK, later by the ASME. It still is considered the most fundamental (which its title states) work in this area.
BK
RE: Stress Relief vs. Normalization
This is not saying this process doesn't work but based on my experience there has got be more definitive and measurable results for it to be a viable alternative to the thermal process of stress relieving.
RE: Stress Relief vs. Normalization
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BK
RE: Stress Relief vs. Normalization
It is a 62" long a992 10wx88 wide flange I-beam with 3/4" thick gussets every 9 inches. It is heavily welded with many 100% welds.
It will be used in a press application and will be subject to cyclic loading (every 3 seconds). As a result I am concerned about fatigue.
Being an I-beam it has some brittleness in the "K-area" from the steel mill. Also due to the extensive welding I am concerned that it might be considered to have heavy constrained welding.
The I-beam is .08 carbon and the gusset material is .18 carbon. I guess you would consider it a mild carbon steel that had no heat treatment from the steel mill.
I think that normalizing it will
1. remove brittleness at "k-zone" and around welds
2. Reduce the "over strength" of the welds as compared
with the base metal
3. And remove welding stresses.
I am concerned that I don't significantly weaken the part. Am I over thinking this?
Picture attached.
RE: Stress Relief vs. Normalization
You might want to download the paper found at this link: ht
Thermal stress relief fared rather poorly against vibratory, in enhancing fatigue life in this study.
Your workpiece would also lend itself well to the VSR Process. Where are you located?
BK