%Cold Worked 304SS

[jscheel15]

I am trying (with no success) to locate some 304SS plate in several different conditions of cold working i.e. 0% (annealed)10% CW, 20% CW etc. Does anyone know of a supplier that carriers 304SS plate (1/2" thick) in varying conditions of cold working (rolling). I am trying to investigate relationship beetween Cold Work % and time to failure when subject to stress corrosion cracking.

any help much appreciated.

 

[metengr]

Contact the sites below. We have done business with them in the past. Most likely, the 304 ss annealed plate can be rolled to the specified reductions either thru them or someone they know (outsource to a fab shop).

http://www.amcastle.com/HTML/cm_pr_stainless_plate.html

Another supplier I have worked with is Scott Forge. The last time I had audited them they had a small rolling mill. They are helpful folks.

http://www.scotforge.com/sf_materials.htm

 

[EdStainless]

Most CSCC test work involving cold work is done with wire. It is easy to draw small amounts of wire to different strength levels.
Be careful when you start loading your test samples. Often SCC testing is done at 100% of yield. When you have an annealed sample at 40ksi yld and 90ksi UTS that is one thing. But what about a worked sample at 160ksi yld and 175ksi UTS? You can't load that sample to full yield and then say that cold work is the only significant difference.


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[metengr]

As an alternative to the above, there is test data published for 304 SS that was pre-strained to 40% CW and tested in boiling MgCl₂with an applied tensile stress of 196 MPa. This data is in the form of a graph of time to failure versus %CW in John Sedricks book on Corrosion of Stainless Steels, page 280. So, you might not need to conduct this testing.

 

[EdStainless]

I guess that I will make another comment. This is concerning what constitutes a SCC failure. While time to failure may be easy to measure I believe that the data has no statistical relevance. The fraction of samples at one condition that eventualy fail is more useful information. Using a probabalistic approach is better for events that are as fast as SCC.

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Rust never sleeps
Neither should your protection

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[jscheel15]

Thanks to all for the help, Metengr the link was a big help.
FYI I am aware of existing work on this subject, my investigation is quite a bit more complicated than I mentioned above, however, I am not at liberty to discuss specifics. Suffice to say there is a reason I need cold worked 1/2" thick plate vs. the conventional wire or thin bend samples used in Boiling MgCl2 testing (ASTM, other work etc.).

Ed, the statistical (probabalistic) approach is indeed what I am using for my investigation. There are an additional number of variables I am concerned with outside of the time to failure. Thanks for the advice though.

Again, thanks to both of you

 

[EdStainless]

jscheel,
I have always wanted to do some CSCC testing involving electrochemistry. This way you could deliberatly break the passive film without having to wait. This is the biggest hangup with doing tests in less agressive environments, the time gets so long that it isn't practical.

= = = = = = = = = = = = = = = = = = = =
Rust never sleeps
Neither should your protection

http://www.trent-tube.com/contact/Tech_Assist.cfm

 

[jscheel15]

Ed,

I have done some accelerated electrochemical corrosion investigations (mainly w/ 7000 series Al)with regard to post machining surface enhancement and the effect on the polarization curve. The tests are very quick and allow an in depth analysis of the DC polarization curve. I have not tried it with the specimen under any load though, just simple rect. coupons. The testing takes only around 30-40 min and provides usefull comparisons in a condsiderably shorter amount of time. Standard SCC in say 3.5% NaCl takes forever, I have made a habit of spiking my solutions (if appropriate) with NaNO3 to speed things up a bit.