I don't know if this is helpful to you or not, but if you are looking to determine what the N08020 is, the chemical composition, etc. This website may be useful to you.
What is the application?
What do the steel companies recommend?
In general, my first thought is to use the alloy 20 filler. The materials are close enough.
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Rust never sleeps
Neither should your protection
If you want to make a heterogenouos welding, where at least one base metal is stainless steel, always use the Schaeffler diagramm. My first guess would be a high alloyed filler metal, for example Citochromax-R (this is Oerlikon), with Cr18%, Ni9% and Mn6%. This would give you almost for sure an austenitic weld, so very likely no cracks would appear. On the other hand you must check the mechanical properties of this filler metal to the base metals. If it doesn't have enough Rp02, then you should choose something higher, like Cr20%, Ni12%, Mn6% or even higher. These are from Esab, code OK. Good luck. Bye!