Preparing steel for forge welding

rhrocker

rhrocker

Joined
Jan 18, 2004
Messages
1,135
Mill scale, I just don't like the stuff. I grind it off using my 4.5" right angle grinder with a course disk. If the steel is fairly thick, I clamp it in my vise so that I can completely grind the entire side at once, before flipping it over and grinding the other side. On thin stuff though, I clamp to the workbench and do 1/2 at a time of each side, changing the clamp 4 times. I've been thinking about buying a inexpensive magnetic chuck just for doing this grinding, seems I could put several pieces on the chuck and grind away, then release, flip, and grind the other side. Someone suggested an acid bath, will this get it all? On a 21 stack billet, this is about 40 sides to grind, time consuming for sure, but I dare NOT do it. BTW, I also even grind the 15n20, seems I can see a "layer" of something in it also. How do you guys handle this problem? Does anyone try and grind the entire length of material first before cutting into peices?
 
When using white vinegar I soak over night then take a wire brush to it then soak for another 12 to 24 hr. Muriatic acid works faster but is harder to get rid of. Gib
 
I used to grind all the mill scale off also. Got tired of all the work, started using anhydrous borax (I think this helped a lot) and quit all the grinding. I have not had ANY bad welds because of the mill scale. Let the flux work and it will take care of the scale. The only time I grind anymore is when building layer count up and then only if there is heavy, old flux on the bars. Then I will grind down to shiny material and reflux.
 
I used to stack, weld, fold, weld, until finished with no grinding with pretty good results, I would find an occasional cold shut or flaw. Now I grind all mill scale, stack, weld, draw out long, grind clean, cut into 4 or5 pieces, stack, weld and do it again, I have NO flaws or cold shuts this way, it's a little extra grinding but I think it's well worth it. I also grind my bar stock with an angle grinder before I cut it up, It's much more easy to grind one long piece than it is to grind lots of short pieces. I don't grind my 15N20, it's clean enough,no mill scale, and I don't grind off rust, it's not a problem.
You can have good results without grinding the scale off but I think it's a little risky, the flux will get rid of the scale but you have to make sure you use enough. Muraitic cut 1/2 with water works very good in about an hour, you still have to wire brush a little.

Just my .02,

All the best, Don Hanson :D
 
I like all the ideas. Staying away from the chemicals would be nice, but apparently it must help a lot. I like Don's method of sanding the entire piece, makes sense to me. Now to rig up a grinder with a spring loaded platen, and run all the long pieces through it :p Seeing as how I'm no Devin Thomas, I guess I'll stick to a less involved method. I'm surprised Don about the 15n20. When I grind on the stuff, I can see a definate coating (not the correct term) of something that's being removed. May be a patina of some sort from exposure to the air. That would eliminate a lot of work by not grinding the 15n20.
 
Hi Robert,
Tina says hi also. There is absolutely no reason to grind 15N20, I've used around 300 lbs in the last 10 years and never ground any to make damascus.
You are right about the patina or oxide but you don't need to grind it off :D
Also the 1080 I've been getting from admiral has very little scale and is easy to grind off, I got some 1/2''X1 1/2''1080 from them that apears to have no scale at all and I'm not even grinding it,welds up fine :confused: The 1084 I used to get had a thick scale that took a little work to get off and 203E is the worst for scale.

best regards, Don Hanson
 
I've had pretty good results with regular mule team borax and not grinding scale off, provided there are no pits to trap flux. I don't have a problem welding rusty steel either. I grind most of my stock though if there is any pits, if it's got pits I'll get traped flux every time, if it's smooth steel with scale I don't grind.
 
I grind everything clean before I start my welding process, I also grind clean with a 4" angle grinder between each and every fold and or weld. Nothing welds better and easier then good clean steel, and I look at it this way. If I'm going to put several hours into making a piece of damascus I don't want any weld problems or inclusions because of scale that I could eliminate with a little grinding, there are several factors that can mess up a piece of damascus, so the more problems a person can eliminate the better. I also use plain ol 20 mule team borax for my flux, I've tried anhydrous and never could find any difference in my welding capablities, maybe if I didn't grind clean every time before rewelding it would make a difference, but the way I work in my shop plain borax does great.

Hope this helps a little.

Bill
 
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