Welding a nut

alderotes wrote: > I haven't see the Phosphoric acid cleaners rust

Phosphoric acid converts Iron oxide to iron phoshate, which is a rust resistant coating. See also Naval Jelly.

Stuart

Try _dilute_ phosphoric acid - a great source for rust problems.

If you're using it for deliberate rust conversion, use it as concentrated as you can handle.

I had milled some Iron making a tool and wanted to blacken it a bit to inhibit rust. I dumped it in a bucket of Phosphoric acid and planned to get it out after dinner. The next Saturday (almost a week) I saw it in the sink and found that about 1/8" of material all-over was removed. That was some hit! So it really depends on the concentration or volume of materail - will it deplete before going to far...

Martin

Phosphoric acid has no blackening effect on steel. If you want to do this, use a selenium cold-blue (any gunshop, Phillips is the best black I've found).

If you want to do it with phosphoric acid, then you need a layer of rust to work with first. Apply a gunsmith's "browned" finish, a controlled rusting, then use conc. phosphoric over that.

You could also parkerize parts - another phosphide based process. A bit complicated though, but gunshops should be able to arrange to have it commercially done.

A quick soak in vinegar will accomplish the same thing. Rinse well immediately after removal from the vinegar though!

Pete

Thanks for all the options guys. I finally just ground off the zinc coating. I probably should have left one coated just to see if it welded any different. I would imagine that it would have just put out a bad gas, but welded the same. Just guessing though.

Jim

The phosphoric acid works a treat. I used some left over 'surface prep' stuff and it had all the zinc off in less than 20 min. without heating.

Even though I welded the nut in place with thread anti-sieze on a through- bolt, the bolt refuses to be removed after welding. The bolt rotates about 1/8 turn but that's it.

Should I forget the anti-sieze and just run a tap through the nut after welding?

Thanks

--Winston

I have welded nuts in place and done similar operations many times. I have a can of "Pure Nickle" Never-Seez which is rated for 2600F. That stuff really works well.

It helps but do try the above mentioned stuff.

Ted

Thanks, Ted.

I found this stuff at McMaster-Carr:

10295K29 Premium Grade Nickel Antiseize Lubricant 1/4 Ounce Tube Temperature range is -65° to +2600° F. $4.88

I will try it out as soon as my order gets here.

--Winston

How come you don't use oxy-acetylene? It works well if you wish to reduce large pieces to smaller ones. It will embrittle the end surfaces which will require machining if you are doing high stress end result work. Ti work hardens which is why you would want to machine any critical surfaces.

how much the fire hazard was. No big deal at

Out of curiosity and not that I have a big 'burning desire' to try it, but how about plasma cutting Magnesium? That has to raise the hackles, if not the insurance rates...

Lawrence Farries