Residual Stresses from Quenching
Residual Stresses from Quenching
(OP)
We just had some 316 SS parts solution heat treated after welding, and instead of quenching from 1650°F to 1000°F then air cooling to room temperature as per our procedure, the heat treaters quenched it from 1650°F to room temperature. Would re-running the solution heat treat procedure (properly this time) remove the residual stresses caused by the rapid cooling? Are there any other issues I need to be aware of, distortion, etc...?





RE: Residual Stresses from Quenching
You would get the same result reheating to 1000 and then slow cooling.
= = = = = = = = = = = = = = = = = = = =
Plymouth Tube
RE: Residual Stresses from Quenching
Why are you even step cooling 316 stainless steel? For a proper solution anneal you should be rapidly cooling to ambient temperature, step cooling will result in lower corrosion resistance.
RE: Residual Stresses from Quenching
RE: Residual Stresses from Quenching
Stanweld, you are right. It is a stabilization heat treat, not solution.
RE: Residual Stresses from Quenching
Precisely. Step cooling of this material will achieve little benefit in terms of residual stresses. In fact, step cooling will undo what you have attempted to achieve with a stabilization heat treatment.
RE: Residual Stresses from Quenching
If not then you have about the corrosion resistance of 410.
If you actually plan to heat to this temp then there is really no reason to rapidly cool at all since you will probably not be able to avoid formation of sigma and carbides.
= = = = = = = = = = = = = = = = = = = =
Plymouth Tube
RE: Residual Stresses from Quenching
Learn the rules,so you know how to break them properly.
Dalai Lama
_____________________________________
RE: Residual Stresses from Quenching
We would seldom attempt to stress relieve SS, especially weldments, as there were no measurable benefits.
RE: Residual Stresses from Quenching
"Vibratory stress relief is not an option for stainless steels."
Vibratory stress relief is very commonly applied to stainless steel fabrications, due to the problems associated with using PWHT on such components. The options are to use what is called a "low-temperature" stress relief, which many manufacturing engineers feel has little benefit to issues involving dimensional stability, or to use a higher temperature heat treatment, and quench, as described above.
On large and/or complex components the quenching option is either not possible, or can re-establish a new set of stresses, having little to do with the original pattern of HAZ's, but much to do with the quenching method and cooling details. This new stress pattern might well threaten dimensional integrity more than the as-welded component, so typically PWHT is not performed on such parts.
There are reports showing examples of vibratory stress relief applied to stainless steel components at:
http:
One of the entries does not involve stainless steel, but rather, pure titanium, but was included since this material machines very much like 300-series stainless (tough, gummy, heat not carried away by chips very well). This report also shows the effectiveness of the VSR Process, in that dimensional accuracies of a few 0.001" were maintained on a population of ~ 80, 144 inch long parts, despite having extremely asymmetrical machining performed that removed more than 30% of the material during rough machining alone.
These reasons explain why the use of vibratory stress relief is one of its MOST COMMON areas of application.
RE: Residual Stresses from Quenching
I presume that this is 316Ti. The best thing to do is verify that you have stablization. If you do then leave it alone.
VSR does not remove stresses, it helps equalize them and make them more uniform. If your part has uniform high residual stress then VSR will not change anything. If the stresses vary a lot then it helps a lot.
= = = = = = = = = = = = = = = = = = = =
Plymouth Tube
RE: Residual Stresses from Quenching
RE: Residual Stresses from Quenching
It can be seen at:
http:
In this work the authors claim to have relieved an average of 90% of stresses in multiple samples of 3 different alloys. This paper has stood up very well to peer review for more than 25 years. I have yet to find a single work that questions the validity of these conclusions. I would be very glad to receive such; please submit such work to the library for consideration of inclusion. We would welcome any work that refines our understanding of this technology.
BK
RE: Residual Stresses from Quenching
I speak from having for many years of work in attempting to straighten and stress relieve metal parts. There is essentially no problem with CS weldment or not, but working with SS it's a new ball game. As far as straightening I go with the sage advice given me many years ago when I asked about straightening as stress relieving a 22 ft long SS screw looking device with a 22 in dia central hollow shaft. The answer I received was repeat after me "Our father wh........ " We spent several thousands' of dollars attempting to use VSR on this part on two occasions in an effort to keep this component from squirming, worming, or snaking when put into operation. Our goal was to kept the 22" dia packing journal from running on an orbit in the packing gland. Our solution was to rough machine and heat this component to the maximum temperature it will see during it's service life. We tried VSR at this point in time with no success. Then using flame to correct the shaft runout on both both ends to 0.010". The component will then be final machined and run out brought to 0.005" or less. During operation we let the center section act like a crankshaft.
As far as solution annealing I have solution annealed, water quench, many pump housings after weld repair of the casting. It might require a skin cut on the back plate landing area. Normally the nozzles are withing OEM tolerance, feet to nozzle center-line and gasket plane.
Our development group tried VSR much to my chagrin on several machine bases and frames and much to their surprise it didn't work.
A much better method is how the Swiss and Henry Ford did it. park it outside for a couple of winters.
My final test was a couple of SS U-bends, the VSR coupons broke in the same time frame or a little faster that he untreated ones.
RE: Residual Stresses from Quenching
Quote: There are reports showing examples of vibratory stress relief applied to stainless steel components at:
http:
With all due respect, is it possible that in the examples of attempted VSR on SS you were associated with that the required resonant frequency was incorrectly established or maybe the amplitude was insufficient? Is there some explanation why SS is not susceptible to VSR?
I do not understand your contention because in one place you say, "There is essentially no problem with CS weldment or not, but working with SS it's a new ball game." But in another place you say, "If the stresses vary a lot then it helps a lot." This last comment you made wr2 SS.