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> Weld filler for AISI 305 to AISI 321
post May 5 2020, 08:05 AM
Joined: 5-May 20

Hello, everybody,

Hope everybody is doing well. laugh.gif

I have a question on chosen of weld filler.
I need to weld a bracket (AISI 321) to a tube (AISI 305), what weld filler shall I choose?
I search on the GE SPM, it seems that I can use AMS 5786 as filler, am I right?

Thank you for your time and help.
Best regards, Will
Technic Al
post May 5 2020, 05:48 PM
Joined: 14-Oct 03

In my opinion the Ni Alloy 5786 is over the top. Basically 321 and 305 are slight variations of 304L stainless and 308L weld metal is designed to weld these..Therefore Id use 308L stainless.
post May 8 2020, 04:13 PM
Joined: 3-Jul 06

I thought that the rule of thumb was to use the filler metal of the higher grade stainless, therefore AISI 347 wire. 321 is a stabilized grade of stainless thus preventing carbide precipitation (rusting)
Technic Al
post May 8 2020, 08:53 PM
Joined: 14-Oct 03

347 is 19/9 stbilised with Niobium. 321 is 19/9 stabilised with Titanium...same thing really...but the stabilisers are only useful if the Carbon is high....neither of the materials mentioned are higher Carbon...Why would you go for the higher grade...its the lower grade that will fail...so as long as you meet the lower grade you will be OK.
post May 10 2020, 10:27 PM
Joined: 3-Jul 06

I guess the service conditions of the bracket/pipe need to be taken in to consideration example temperature range. Regards to filler metal choice look at the charts 347 is the first choice and 308L the second. If welded with 347 the weld would have a higher temp ranges less chance of failure.
Technic Al
post May 11 2020, 12:46 PM
Joined: 14-Oct 03

Thats right 347 can withstand slightly higher temperatures, depending on the carbon content...however, not all 347 has what is deemed high carbon (in stainless terms). Usually if you need high temp resistance you probably wouldnt choose any of the alloys mentioned and if you want to weld it with 347 there is a H version that guarantees the higher carbon content. There is also the age old 347 problem of slag sticking. For some reason the Nb makes the slag stick like S to a B and can result in some ugly welds. As I said I wouldnt expect any of these alloys to be chosen for its temperature resistance so providing you meet or exceed the properties of the weakest component (probably the 305) you will have produced a joint that will outlast at least one component and in this case maybe both...305 is designed to be worked and is often the choice for the best stainless steel sinks and kitchen equipment....so I would choose 308L as its the most common....347 is normally restricted for use in welding either 347 (very rare) or 304 (normal carbon) when it cannot be heat treated afterwards.
post Jun 2 2020, 09:25 PM
Joined: 7-Apr 20

Technic Al. Been looking at your input for decades now pal and gained a massive amount of knowledge from you re metallurgy.Why-
"347 is 19/9 stabilised with Niobium. 321 is 19/9 stabilised with Titanium...same thing really"? I'm guessing that the Ti/Nb impart different benefits due to either service or workability (heat treatments/ductility)
Technic Al
post Jun 3 2020, 09:22 AM
Joined: 14-Oct 03

Its almost a national thing....347 was mostly America and 321 was mostly Europe...I think it was down to the availability of the Nb or the Ti.......they both do the same thing....If there is a difference the 347 maybe slightly stronger at higher temperatures but its close.
In welding 347 is always used because Nb will pass across an arc but Ti just boils away.
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