I agree entirely with Lawrence.
Just to add a few words, it's easy to run a chemical analysis on the forks material, that will give you a good idea on what filler metal to use, but this answers just a part of the question.
The other part is the heat treatment the forks have undergone, of which a metallographic analysis and a hardness test will give you only a vague indication, and of which the manufacturer won't tell you a word.
Of course, before attempting any weldment on the forks you'll have to remove any heat treatment present in them, which is easy to carry out. BUT, after the weld is complete, you'll have to submit the fork to the same heat treatment they received at the manufacturer's plant, which you don't know.
So, the best solution is Lawrence's one: buy a new fork.
Giovanni S. Crisi
Sao Paulo - Brazil
It's been awhile. I found more favourable venues for me. LOL
I work for a company that modifies forks to customer specs. We have low quality fork blanks from China and add clips or eyes to them. We use Metalloy 110 1/16 inch wire with Moongone gas from Praxair (I can't find any documentation for the Ar/CO2 mix in that stuff).
Many of the forks are freaking huge and we have to weld everything in the flat position which is dangerous, I broke my leg on a "small" 500 lb fork. I welded eyes on some last week that were 4" thick, 10" wide, 120" long with a 50" back. I'm thinking 1500 lbs per fork. So we use overhead hoist to stand the blades of the fork up in the air so we can access the weldment in the flat position. OSHA would have a field day with some of the sketchy techniques we use to build these monsters.
Anyways, in reading the documentation from Hobart on the wire, it states that this wire CAN weld horizontal, flat and vertical down using spray transfer and all position using Pulsed MIG. I would like to find out any code for these damn things so I can stack up some ammo to present to the boss to invest in Pulsed MIG machines that would allow us to weld all position to make it safer as well as increase production. Most the time we can weld them out, the final pass on some fork eyes are 3 inch wide weaves, in a couple hours. Most the time we waste is trying to wrestle these things into a position that won't kill us and we can get the joint flat.
At times we have to add material to make the backs higher. So instead of a bevel full pen weld they have us placing a 1/2 to 1 inch rod in between the sections and weld up as a square butt. It's nerve racking to get this things into position to weld without the chance of them slipping off the hoist. There was a very close call with an 8" fork and a coworkers body the other day. So I'm trying to get something together to present to the CEO to help us help them and save our a$$es in the mean time.