E 309L welding with/without preheating

[Jap1]

We have joints that need to be welded with E 309L Flux cored arc welding. One of the base metal is 2" thick mild steel (A36), and the other is 0.5-1" thick 304L. My question is whether pre-heating for the mild steel is required or not because of the weld metal of 309L. I believe that hydrogen cracking on HAZ of the mild steel is low. What is your experience on 309L dismialr welding?

 

[kingnero]

For 2" think carbon steel, I'd apply at least some preheating...
Take care to avoid lamellar cracking. Have recently had this problem with welding padeyes on low carbon steel, 25-30 mm thick base metal. They ripped right off.

 

[r6155]

Which is the code?

Regards

 

[weldstan]

You should preheat at 200F minimum. High residual welding stress + high potential for martensitic structure in HAZ makes potential for HAZ cracking high.

 

[Jap1]

Thank you for your valuable advice. I'll keep it in mind that preheating is needed. As I cheched carbon content of A36, it's quite high.
We are located outside of US, but we build it for the US customer,so I'm not sure which code is applied. It's not a pressure vessel, as welders don't need a pressure welding ticket.

 

[r6155]

Be careful. The welding procedure specification and welder must be qualified for this example.
AWS D1.1 is for structural.
Regards

 

[kingnero]

We're talking 2" thick A36 in a dissimilar weld, with an OP who's asking about preheat, and you guys are worrying about the certs? I'd say there are bigger worries than the paperwork here.

 

[Jap1]

I should have mentioned this earlier, but this is T joint that requires 3/8" fillet weld. The 304L chamber is reinforced with 2" mild steels. If anyone thinks that preheating is not necessary, I would like to hear your thoughts.

 

[r6155]

If (OP) doesn't know the code and there's no mention of a service, how can someone decide whether to preheat or not?
Please, if someone answers, tell the reference.

Regards

 

[Jap1]

I don't want to disclose the detail, but it's a melting furnace shell. I'm not concerned about a code and I would rather know about any cracking issues for this particular welding. I'm asking here because I think that hydrogen dissolves in austenitic weld metal and does not diffuse into the HAZ of A36 steel, but it appears that precaution and preheating are necessary.