ASTM A335 P36 to 316 Stainless Steel

[adaz27]

We have a requirement for welding ASTM A335 P36 to 316/316L Stainless Steel
I believe the ideal procedure would be to butter the P36 with ErNiCr-3 and PWHT, then join to the 316/316L after using ErNiCr-3 again..

However, I've heard of people welding dissimilar joints involving Carbon steel (Similar PWHT temp to P36) & stainless steels and carrying out PWHT on both, as long as you're using a low carbon or stabilised grade stainless.

My question: How can you confirm that the heat treatment cycle hasn't been detrimental to your stainless material in regards to sensitisation? Is there a test I can complete as part of my weld procedure to assess levels of sensitisation? (possibly ASTM A262 practice E?)

 

[EdStainless]

While it can be done the way that you propose, the dilution of the steel in the weld (increased C levels) will assure that you have some sensitization near the weld. If you are not concerned about it (say a hot application with no aqueous corrosion risk) then it might be work for you.

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P.E. Metallurgy, Plymouth Tube

 

[metengr]

The use of buttering would be the preferred approach for several reasons; (1). You avoid unnecessary exposure of the stainless steel side of the DMW to PWHT of the ferritic base material, (2). If this weld joint is exposed to elevated temperature service, you reduce carbon migration (diffusion) by the use of the Ni-base filler metal for buttering and premature failure of the ferritic side of the DMW from creep damage. (3). The coefficient of expansion is better matched using the Ni-base filler between the two dissimilar materials and again adds to longevity.