If I understood correctly, a fork lift truck picked up some 304L material (let's imagine they were pipe fittings) to carry them away from a certain place, and the brief contact with the unprotected lifting forks contaminated the 304L material with no remedy. In my opinion, this is a little exaggerated. Can a contact that lasted, say, five minutes between the two surfaces, have contaminated so severely the stainless one?
When welding stainless steel only stainless steel brushes and alumina or zirconia grinding disks should be used, but this is a different case. The contact between the brushes or the grinding disks and the stainless surface is longer and intimate, whereas the contact between the forks and the stainless material was only superficial.
In any case, if you're going to pickle the stainless surface, there's nothing you should worry about.
This is my opinion; someone may have a different one.
Giovanni S. Crisi
Sao Paulo - Brazil
The issue is not one of carbon contamination. The concern is whether or not "carbon steel" may have contaminated the surface of the stainless steel material. The issue is whether the carbon steel was transferred or embedded as small particles into the surface of the stainless steel. This can happen if there was any rubbing, sliding, abrasion, or scratching while the stainless was being moved from one location to another while on the unprotected forks.
The concern can be proven or disproven by wetting the stainless steel with water and letting it set over night. If any carbon steel was transferred, it will manifest itself as rust stains on the surface of the stainless steel. If there are no rust stains, count yourself as "lucky."
Best regards - Al
Been there done that.
Bechtel and Flour are famous for this.
SS to non SS contact.
Giovanni is correct
On a side note the more I read what Giovanni has to say, the more impressive he is.
Hope this helps.
Thank you for your time and consideration.
Sincerely,
Kent
Kent,
thankyou for your kind (and undeserved) words.
Giovanni S. Crisi
It is Stainless Steel pipe. Forks of fork lift were in contact with pipe for 10 min. max. After resent rain there is now rust marks on the S.S that were not evident prior to C.S forks coming in contact with material. Don't know if that is "exaggerated" or not but thoes are the facts of the case your hornor. :)
Jim
If the pickeling isn't doing the job, the next step is electropolising.
This is a more agressive method for removal of surface iron from contact transfer or iron in the alloy, It leaves a chrome rich surface
Your pickeling operation is the proper method for dealing with transfered carbon.
As to how big a deal transfered carbon is, it will be determined by how critical the part is, the aplication, and how important the visual effect is.
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