Welding 316L Stainless - Heat Input/Heat Affected Zone Rules
Welding 316L Stainless - Heat Input/Heat Affected Zone Rules
(OP)
When welding 316L stainless, are there any code rules (ASME or AWS) that specify the heat input limits/control? Is there a reason to be concerned about heat input for 316L stainless?
Also, is there any real heat affected zone for welded 316L stainless? My understanding is that 316L is relatively insensitive to material property changes due to heat, and also is not sensitive to carbide precipitation. I suppose that the grain size will get (larger?) in the heat affected zone, but I don't think this will have an effect on material properties assuming the material started as solution annealed.
Also, is there any real heat affected zone for welded 316L stainless? My understanding is that 316L is relatively insensitive to material property changes due to heat, and also is not sensitive to carbide precipitation. I suppose that the grain size will get (larger?) in the heat affected zone, but I don't think this will have an effect on material properties assuming the material started as solution annealed.





RE: Welding 316L Stainless - Heat Input/Heat Affected Zone Rules
The practical problem is 'dual certified' stainless steels, which tend to have carbon contents that crowd the upper limit for L-grade. In the region of 0.03~0.04% carbon there is a chance of sensitization, but it takes fairly extreme thermal conditions during welding to do this. If you use normal welding processes and do not let the interpass temperature run away you should be quite safe.
Dual certification is done purely for commercial reasons (less stock is required), but I take a dim view of it. I know it won't happen but I believe that L-grades and straight grades should be made distinct by specifying a minimum carbon content for the straight grade. The two types in general have quite different applications.
RE: Welding 316L Stainless - Heat Input/Heat Affected Zone Rules
RE: Welding 316L Stainless - Heat Input/Heat Affected Zone Rules
RE: Welding 316L Stainless - Heat Input/Heat Affected Zone Rules
No, not for ASME. This is a process control detail.
RE: Welding 316L Stainless - Heat Input/Heat Affected Zone Rules
RE: Welding 316L Stainless - Heat Input/Heat Affected Zone Rules
350° is just good practice. Not just for preventing sensitization, but for austenitic SS's very poor heat transfer properties.