I've got this axle I'm selling soon...and during cleanup I find what looks like a mig weld bead on the inside of the hub that holds the backing plate. Being g new to this I checked another axle hub and there's significantly more wear on the suspect one. I suspect there was a bearing failure and it gouged out the inner surfaces during the process and welded some material to the side via friction??, I don't see any indications on the otherside that there was a Crack and the odd inside buildup was a backside of a weld. So as far as the usefulness of this axle....would the excessive wear make it undesirable for future use? I'd guess there would be some play added now if the bearing and race touch the back area. Thoughts.
A snap ring holds the bearing in the hub and the taper on the axle keeps the bearing from rubbing on that surface, I don't see a problem with the weld unless the hub hits it.
I wouldn't loose an ounce of sleep over that. If it bugs ya just grind it off till you like the way it looks.