e309l electrode for carbon steel butt joint 1

[abangbikerz]

a carbon steel pipe sch 80 supposed to be welded using 7018 electrode. for an unknown reason our welder use 309l electrode for tack weld of this pipe. problem detected and tack weld is removed by grinding. new tack weld is made using carbon steel electrode. problem solved.

but. what if the tack weld is not removed and full weld is made on it. as this joint needs to be fully xray. does dissimilar electrode material will fused completely with carbon steel??

if there is a trace of stainless steel inside the carbon steel. does it shown on xray film??

 

[stanweld]

While you won't see the diluted tack, you may well see the crack resulting therefrom.

 

[Guest102023]

There is a chemical test for detecting stainless steel residue on carbon & low alloy steel, copper sulphate I think it is. The recipe is given in ASTM A380. You use it to confirm complete removal.

The problem is that if enough SS gets diluted into a weld pass along with higher carbon surrounding base metal, you could create a potent mixture. By potent I mean extreme hardenability and consequent cracking tendency, including hydrogen cracking.

 

[REGRUMBLE]

We often use 309 Electrode to do a CWB welder qualification test with 3/4" carbon steel plate. The completed weld is 100% RT examined. You can see the difference in the weld but the dissimilar metals do not indicate there is a weld failure.

 

[metengr]

Austenitic stainless steel filler metal welded to carbon steel base metal will not pose a problem provided it is left "as-welded". This is known as a dissimilar metal weld. Dilution of the austenitic weld metal with the carbon steel base metal does not result in harmful phase constituents in the fusion zone.

The problem you can develop is depositing carbon steel filler metal on austenitic stainless steel base metal because here you are dealing with dilution in the weld fusion zone. In this case, one should never deposit carbon steel filler metal on austenitic material, weld or base material.

 

[abangbikerz]

regrumble. why are you using 309 electrode for that purpose??

 

[metengr]

It is only for purposes of welder performance qualification, and not production welds.

 

[stanweld]

abangbikerz,
There are potential problems associated with incorporating the 309L tack into the E7018 weld. The dilution of the E7018 over the E309L tack will create an alloy of approximately 5% - 9% Cr and 2% - 4% Ni hardenable ferritic alloy deposit which could be subject to cracking (the reason for my previous reply). And the galvanic mismatch created could lead to decreased corrosion resistance in the service environment or the hardened zone created may initiate stress corrosion cracking in the service environment.