Yes, it is possible with GTAW and even SMAW processes. However, to select the filler metal you would need to know the application - corrosion env or strength and corrosive env, etc.
Ok. Can you be more specific about the above question, namely the actual type of corrosive env and strength in comparison to 316L versus the 17-4PH? The reason I am asking is because 316L has better corrosion resistance in comparison to 17-4PH, however 17-4PH can be heat treated to various strength levels. So, welding this combination of materials has to be done with caution because welding will affect the mechanical properties of the 17-4PH, and your desired outcome.
Oh, sorry. I know very little about welding so I wasn't sure what you were asking.
The enviornment will mainly be seawater, but as far as the corrosion resistance of the materials, it would be best if they changed as little as possible. Basically the unchanged corrosion resistance of the 17-4PH would be the desired corrosion resistance of the welded structure.
As for strength, consider the unchanged strength of 316L as the bottom line for the welded strength of the 17-4PH.
Basically, both materials are suitable for the application alone, so the welded structure should have properties similar or better than the worst of the two materials.
The filler metal would be 316L in this case to join the 17-4PH using the GTAW process. No preheat, keep the interpass temperature below 300 deg F and no post weld heat treatment. The 17-4PH should be in an 1150H condition. You understand that the 17-4PH will develop corrosion pits in this service.
