welding of SS304L to SS316L

[ramakant]

i want to know if i can weld SS304L to SS316L....what will be changes in the weld pool :metallurgy wise and other mechanical preoperty wise..what will be impact on the corrosion resistance of the material(weld pool)...

regards
Ramakant

 

[rd400guy]

First off, pretty much the only difference between the two is that 316 has ~2.5% Moly, so you can definitely weld the two.

Since you're using the L (low carbon) versions of both grades, sensitization shouldn't be a problem, and therefore corrosion resistance and other properties of the weld metal should be at least equivalent to the 304 base metal.

What welding process are you using, I'm assuming GMAW or GTAW? If GMAW, are you using any filler material?

 

[GRoberts]

As far as welding the two together, they are practically interchangeable. You can get acceptable welds using all of the common stainless welding processes and with filler metal suitable for either base metal. The two metals are the same P No. and Group No. in ASME (as long as you are using classified material), so new procedures would not even be required. As far as corrosion is concerned, if both base metals will be suitable for the environment, either 308L or 316L filler metal would be also.

 

[unclesyd]

As stated in previous post you can weld 304L/316L with filler rod for either metal as long as the filler rod is “L”. If you don’t need the “L” either filler rod will still work.
A general rule of thumb is that when welding two different metals you would weld with the more or higher alloyed base metal filler rod. This is just a guide line and not a requirement.

 

[ramakant]

thanks rd400guy,Groberts and unclesyd for the prompt response.i do agree with you all that we should use the filler wire of superior grade material. but i have a doubt that in long run will there be some problem in the weld. and strength wise the weld will have properties better or inferior than the parent metals ...i guess it should lie between the two.


regards
Ramakant

 

[Metalguy]

If Cl-containing water is on the inside of the piping, there will probably be enough Mo dilution from the 316L in the root pass to prevent pitting--if the 316L itself is adequate.

 

[bmoorthy]

Firstly when you say your welding 304L to 316L, then it is automatically asumed that the service is such that both the material are compatible, in which case whether you choose E316L or Er316L or E308L or Er308L or Autogenous welding, does't matter so long as you have a qualified procedure or follow Standard WPS. The tensile properties of both are almost identical, hence there is no problem. I do not see any metullargical problem as you are welding Austenitic to Austenitic. If you have any ferrite restrictions then you may have to choose appropriate filler wire(Do a mock weld and check the manufacturer's claim)