welding with Softweld 55Ni

Date 01-09-2007 18:54

I am using "Softweld 55Ni" stick consumable electrode for welding heat treated 4340 (220 ksi) to mild steel. The weld will not be under high stress and I don't need high strength from the welded assembly in the weld area.
I am using the consumable as a austenitic stabilizer to keep hydrogen in the matrix. I will be preheating to 600 F, and slow cooling after the welding at 50 F per hour.
The Softweld 55Ni is not a low hydrogen rod.
Anybody have experience or see any problems with this?

Thanks

By Sourdough (****)

Date 01-10-2007 01:28

Seems like you have the process licked. Slow cooling is the key, mind that.
No problems here, some of the fellas here will give you the dictionary version, WHICH, is great, because sometimes it helps a bunch to know why you are doing what you're doing!!

By billz

Date 01-12-2007 18:21

I see that some text book answers may be to use a consumable that has a chemistry similar to 4340, like UTP 62 Super Ti, which is stated to be designed for 4340, 4140 etc. But at a tensile of 120 ksi, seems like your asking for problems with high hardness and potential cracking, especially after dilution of more alloy form the parent metal. Seems to me if avoiding a post weld crack, using a low strength filler that is very ductile is the way to go.

By Dr. D

Date 01-16-2007 13:50

You might also want to look into and try Super 600 Rod. Very good to use when welding dissimilar steels.