Filler wire for touching up thin walled 4340 EB welds?

[stillcrazy]

My firm produces a weldment made of 4340 steel that is EB welded at an outside vendor. At times post weld machining does not fully clean up the weld zone. I would like some info on the correct filler to use for touching up the affected area. The wall thickness is approx. .100 thick. These are small visual indications perhaps .010 deep. Is there a recommended pre-heat / post heat cycle?
I have an AMS spec (6456D)that pertains to 4340 welding wire but none of the supply houses seem to understand what I'm asking for.

Thank you in advance for your help.

 

[metengr]

stillcrazy;
For some strange reason, I thought this question was asked before? If not, why bother to weld for 0.010"? Is the wall thickness something that can vary so that you can carefully blend/re-profile the surface to remove the 0.010" undercut or low spot?

Welding of 4340 requires elevated preheat and you could get around without a post weld heat treatment cycle depending on what you can tolerate in terms of hardness and toughness. Also, why don't you have the vendor doing the EB welding add filler metal on the surface using GTAW to PWHT and then machine, to avoid this problem in the future?

 

[GRoberts]

In addition to Metengrs's fine advise, you don't want to use the 4340 filler metal unless you plan on giving the weldment a quench and temper PWHT. Otherwise, the weld will be much harder than the base metal. The filler metal you do need to use depends on what properties the base metal has. You can get GTAW filler metal from 70-140KSI that I am aware of. If you need matching strength select the appropriate strength level of filler metal.