If these need tolast a long time, I would wrap the 3/4 steel all the way around the axle, form the loop and wrap the end around the axle too. Weld the wraps shut and weld to the axle so it cant slide off. I would do this as a longer lasting job from a rust standpoint. This way the entire 3/4" has to rust off, not just the weld beads. The eyebolt and nut is good too, use a real big eyebolt and weld the nut fast. By the way, is this to sink something or to hold it in place like a mooring?