It is currently Mon Dec 18, 2017 8:54 am Advanced search

Best way to weld SS to prevent crevice corrosion??

What welding projects are you working on? Are you proud of something you built?
How about posting some pics so other welders can get some ideas?

Re: Best way to weld SS to prevent crevice corrosion??

Postby Otto Nobedder » Wed May 10, 2017 8:44 pm

exnailpounder wrote:
Otto Nobedder wrote:I would use 316 throughout, and an over-alloyed (fully austinitic) filler. Eliminating ferrite in the weld will go a long way to stopping crevice corrosion. Here's a quote from a discussion I had recently with a welding engineer, "Examples of filler metals which solidify austenitically are AXT, 310, 310L, 383, 385, and a urea grade 25.22.2.LMn."

Note, the reason most common fillers leave residual ferrite is to prevent hot-cracking of the weld, which means you have to control both heat input (Pre-heat is advised) and cooling rate, perhaps even peening the weld during it's initial cool to interpass temperature.

Steve

So..in your opinion..would 316 work throughout? I think it would. I have been in refineries and seen all types of SS take some serious abuse and hang in there. Refineries are not the place to say...maybe this'll work :lol:


Yes, when welded with 310/310L or the higher alloys mentioned above. Austinitic stainless is succeptible to stress-cracking in a chloride environment (salt water) when there are grain boundries between the austinitic phase and the ferrite crystals in a 308 or 316 filler weld. A fully austenitic weld "should" prevent or reduce that.

Steve
User avatar
Otto Nobedder
Weldmonger
 
Posts: 8405
Joined: Thu Jan 06, 2011 11:40 pm
Location: Near New Orleans

Re: Best way to weld SS to prevent crevice corrosion??

Postby exnailpounder » Wed May 10, 2017 8:46 pm

lostsoul wrote:The rudder is a 1974 on a 1974 boat. I have owned the boat for 20 years.
As far as I know, the rudder was not rebuilt before I owned it, but I cant be sure. There are many other boats of the same model and year and some owners have rebuilt theirs. Many just scrape out the old foam and dont really expose the welds. But others have done something similar.

But this method of rudder building is common. It tends to last a long time. I could buy a replacement rudder which would be built in the same manner. Big bucks though. There is a place called Foss Foam that makes new rudders. I think they use all SS and not a more corrosion resistant alloy. Thing is to keep the sea water out is key. But it will get in at some point, it is just a matter of time.

I have the 316 post and ribs pretty much set to be welded. I stopped by a shop and they said "no problem, be less then $100". But they dont seem to understand that this welding needs to be well done to be corrosion resistant. For me, I dont know exactly what they should do. Maybe I should trust them? I would like to learn more about this so I get it dont the best it can be. After all I dont want to have my rudder fail. It is not like a flat tire.

I know that the old ss post was welded to plain steel for 40 years and did not fail. (almost). I just like to do things the right or best way. I am not a good enough kind of guy.


Thanks for the comments guys!!
frank

Frank..I understand wanting to do things the right way and that is truly commendable. I think your set up in 316, properly welded, will outlive us all and be safe. I know it would suck to snap a rudder at sea but if you find a competent welder you should have no worries. I heard Lt Badd is going to contact you. He'll make sure it's done right.
Ifyoucantellmewhatthissaysiwillbuyyouabeer.
exnailpounder
Weldmonger
 
Posts: 2461
Joined: Thu Dec 25, 2014 9:25 am
Location: near Chicago

Re: Best way to weld SS to prevent crevice corrosion??

Postby exnailpounder » Wed May 10, 2017 8:52 pm

Otto Nobedder wrote:
exnailpounder wrote:
Otto Nobedder wrote:I would use 316 throughout, and an over-alloyed (fully austinitic) filler. Eliminating ferrite in the weld will go a long way to stopping crevice corrosion. Here's a quote from a discussion I had recently with a welding engineer, "Examples of filler metals which solidify austenitically are AXT, 310, 310L, 383, 385, and a urea grade 25.22.2.LMn."

Note, the reason most common fillers leave residual ferrite is to prevent hot-cracking of the weld, which means you have to control both heat input (Pre-heat is advised) and cooling rate, perhaps even peening the weld during it's initial cool to interpass temperature.

Steve

So..in your opinion..would 316 work throughout? I think it would. I have been in refineries and seen all types of SS take some serious abuse and hang in there. Refineries are not the place to say...maybe this'll work :lol:


Yes, when welded with 310/310L or the higher alloys mentioned above. Austinitic stainless is succeptible to stress-cracking in a chloride environment (salt water) when there are grain boundries between the austinitic phase and the ferrite crystals in a 308 or 316 filler weld. A fully austenitic weld "should" prevent or reduce that.

Steve

I have read about a few SS filler rods that are supposed to prevent and/or lessen carbide precipitation in the HAZ...I can't recall what they were but from what I have been able to ascertain, 316 should be the ticket. Gosh...what do you do for a job so simple but so complex?
Ifyoucantellmewhatthissaysiwillbuyyouabeer.
exnailpounder
Weldmonger
 
Posts: 2461
Joined: Thu Dec 25, 2014 9:25 am
Location: near Chicago

Re: Best way to weld SS to prevent crevice corrosion??

Postby Otto Nobedder » Wed May 10, 2017 9:01 pm

My job's not as complicated as this.

My curiosity leads me to information like this. Remember the discussion about why stainless becomes magnetic in certain situations? This information comes from my research into that question.

I might never use it, but now I know it.

Steve
User avatar
Otto Nobedder
Weldmonger
 
Posts: 8405
Joined: Thu Jan 06, 2011 11:40 pm
Location: Near New Orleans

Re: Best way to weld SS to prevent crevice corrosion??

Postby lostsoul » Fri May 12, 2017 12:04 am

IMG_5145.JPG
IMG_5145.JPG (97.81 KiB) Viewed 323 times
Thanks guys.
Been a while since I have been in discussions of ferrite, austenite, body centered cubic, face centered cubic, etc..

My conclusion is that I will just make sure the welder uses a 316 rod when welding. I know there could be more done to treat the weld, but not sure it is necessary. It would be nice to know though. I doubt this much thought went into the original fabrication.

I am posting a couple of pictures to go with an email exchange with Richard..
lostsoul
New Member
 
Posts: 5
Joined: Tue May 09, 2017 9:25 pm

Re: Best way to weld SS to prevent crevice corrosion??

Postby lostsoul » Fri May 12, 2017 12:06 am

only one pic loaded, here is another
Attachments
IMG_4924.JPG
IMG_4924.JPG (42.29 KiB) Viewed 323 times
IMG_5183.JPG
IMG_5183.JPG (65.84 KiB) Viewed 323 times
lostsoul
New Member
 
Posts: 5
Joined: Tue May 09, 2017 9:25 pm

Re: Best way to weld SS to prevent crevice corrosion??

Postby Olivero » Tue May 16, 2017 6:43 pm

Make sure it gets repassivated, Im tellin' ya, it'll make a big difference.
if there's a welder, there's a way
User avatar
Olivero
Ace
 
Posts: 386
Joined: Tue Dec 13, 2016 9:24 pm
Location: Clearwater Florida

Re: Best way to weld SS to prevent crevice corrosion??

Postby lostsoul » Tue May 16, 2017 8:15 pm

Olivero wrote:Make sure it gets repassivated, Im tellin' ya, it'll make a big difference.


I asked a shop about that and he said that passivization was not needed because the metals were the same....

thanks for the reply
lostsoul
New Member
 
Posts: 5
Joined: Tue May 09, 2017 9:25 pm

Re: Best way to weld SS to prevent crevice corrosion??

Postby LtBadd » Tue May 16, 2017 8:22 pm

lostsoul wrote:
Olivero wrote:Make sure it gets repassivated, Im tellin' ya, it'll make a big difference.


passivization was not needed because the metals were the same....

thanks for the reply

That's a bad answer, for best corrosion resistance passivation is required. Now that said, I can't say what that means in terms of time, I know your using 316 and this will be much better then what you're replacing
Richard

Insert witty, sarcastic, or philosophical remark here.
User avatar
LtBadd
Weldmonger
 
Posts: 1413
Joined: Sun Apr 12, 2015 4:00 pm
Location: Clearwater FL

Previous

Return to Welding Projects - Welding project Ideas - Welding project plans