stoody 33 wps?

Date 05-23-2007 19:23 Edited 05-23-2007 19:26

have a very large project welding 7018/ er309l -t/stoody33 in that sequence to join a mild steel superstructure with chromium carbide cladding( chromium carbide welded to mild steel backing) any experience with this? as the last project we did like this the wps did not result in 'minimal cracking' in fact it cracked like crazy. also the stoody wanted nothing to do with the cracks in the Cr cladding (my guess that the cracks are excess carbon and the stoody resisted the carbon) also the preheat is 300 f making the job almost impossible. any experienced help would sure be appreciated because it is a very big job for its type and any improvement to welding time even a small % would yield a substantial savings in time, money and exposure to such a harsh product.
thanks
darren
p.s. i am only the welder and not one of the decision makers, i am just interested in completing a successful project for my own reputation

By PhilThomas (**)

Date 05-24-2007 02:16

I'm not sure I completely understand the situation, but it would seem more prudent to strip back the hardfacing, join the superstructure to the mild steel backing, and then re-apply the hardfacing.

Trying to join the superstructure to the cladding layer won't give you much in the way of strength, unless it is completely loaded in compression....and this doesn't take into acount the cracking issue..

By darren

Date 05-24-2007 09:41

this what is happening in the order of 7018 to weld all the superstructure together,7018 to weld the cladding base metal of mild steel to the superstructure, er309l t-1 to cover all 7018 and then stoody 33 to finish all exposed surfaces inside the structure. that way stoody 33 and mild steel never have any contact. the problem is the stoody it does not like the chromium carbide cladding and it cracks very badly when the wps is followed
sorry for the convoluted description
darren

By PhilThomas (**)

Date 05-24-2007 12:16

Its not a convoluted description - just hard to visualize for someone who isn't sitting there...so please understand that these comments are based on what I *think* I understand :)

Stoody 33 should weld over the 7018 with no problems at all. I'm not sure why the 309 is needed.

If this is a Cr-carbide clad wear plate, it uses a much richer alloy system than 33. Stoody 33 has about 2% carbon while the clad plate will probably have more like 6%. This results in a higher hardness on the clad plate and it probably has visible cross-checking. The Stoody 33 should not have cross-checking when welded on mild steel....but if it is being diluted with the higher alloy cladding, then the resulting deposit probably will cross-check (crack).

If the cladding had cross checking to begin with - why would it matter if the 33 deposits had some?

By darren

Date 05-24-2007 22:07

in comparison to the cladding the checking is more significant in the stoody the cladding is three layers, 1/4" mild steel plate /with a 309 type of cnc welded cladding/ then the chrom carbide. have you had procedures developed that dont include such a high pre heat?
this is for a new digester for the tar sands . they steam inject a slurry while it is churning/rotating in a large funnel and then the oil and sand are separated. something similar to a cream separator. we built proto type and now that is a proven technology we are building the large process type ,very expensive/innovative project

i am looking to arm myself for victory in regards to this project, i am a firm believer that information is a force and an overwhelming force applied to any situation yields the greatest possibility of success. i am very competitive and see the opportunity/challenge of a project as an opportunity to compete against myself, which means a majority of the time i am the winner.
i am still trying to figure out if im the only competitor in such a situation sometimes i still seem to come in second.
again the reason why i am arming myself with information
thanks for your input so far and look forward to any other information you might be willing to share
thanks
darren
p.s.will try to get some pics of the welding profiles and wps for posting so as to add some clarity

By darren

Date 05-24-2007 22:10

just looked at your occupation, man am i glad you responded, look forward to any help. last time we put on around 50 boxes of stoody 33 and this project is around 10 times more welding at least. last time we had a hard time sourcing the rod if there are any concerns this time ill post them
again thanks
darren

By PhilThomas (**)

Date 05-25-2007 01:36

If you will post some pics, I will do my best to help you. I'm not familiar with a 309/Cr-C clad plate, but I certainly don't know everything LOL!!

By alumtig (**)

Date 05-30-2007 19:21

I have some experience with chromium overlay plate. The manufacturer recommends for joining purposes that the root (from the carbon side) be welded with a 309 electrode in case the chromium overlay is contacted. This will prohibit any cracking issues that would be created by welding with a mild steel electrode. After the root pass has been made the balance is then welded out with mild steel which will readily join the 309. I normally run a pass of hard surfacing material on the inside of the join to cover where the overlay plate meets. We have had great success welding overlay plate in this manner. I am not sure what the preheat is all about as we have never used a preheat and there were no recommendations by the manufacturer for preheat.