San Mai....in one hit?

kuraki

kuraki

Fimbulvetr Knifeworks
Joined
Jun 17, 2016
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I don't have any mechanical forging equipment yet, and I just don't have the time or desire to do any laminating by hand.

But at work, I have a 400 ton brake press, and flat dies.

I'm thinking of hauling my forge in, TIG welding up a 304/15n20 sandwich, and squeezing it together in one shot. Maybe draw it out a bit as this press is just as fast as most forging presses.

If I can encapsulate the entire billet with the flat dies, assuming I got a good heat, wouldn't this have a high probability of getting a good weld?
 
Yes, it should work. I would advise you to have the forge running at 2300 plus degrees as you weld the entire billet up. be sure all the steel is ground clean and is clean before you weld the billet up. Immediately after welding, put in the forge for 10 -15 minutes. Then go to the break press.
I have used 410ss and 0-1 for my san mai, and have no experience with 304/15n20.
 
I don't know anything about making stainless San mai but I've made some out of 15n20 and 1084. If you clean all the surfaces and grind them free of scale, you can stack them and weld around the entire stack. Then all you have to do is heat it to welding temp and give it a few smacks with a hammer. You press would work fine. Again this applies to high carbon steel's. You just have to make sure you weld around the entire piece.
 
Thanks guys. I'll have to add another burner to my forge to hit the necessary temps I think.

Since it will be a bit of work hauling stuff around I might try a few different mixes.

I have 304 and 316 and 416 on hand, as well as 15n20, 1084, 1095, 80crv2, w2, a2, and o1.
 
If you have MIG, that's quicker and easier than TIG. Just set it so the weld is a bit superficial. ER-70-S6 wire is fine to weld carbon to stainless, for billet purposes.
Tom is right on about weld sides up, throw into preheated forge and soak. 10 minutes has worked for me but longer is common. Good and hot, 2400 degrees even. The 416 is probably your best bet though, you'll get some cool looking carbon migration and it won't want to tear apart quite as much as 304/carbon will during heat treat.
 
Thanks Salem. Also for the inspiration to try this via your Instagram.
 
Tom Lewis said:
Yes, it should work. I would advise you to have the forge running at 2300 plus degrees as you weld the entire billet up. be sure all the steel is ground clean and is clean before you weld the billet up. Immediately after welding, put in the forge for 10 -15 minutes. Then go to the break press.
I have used 410ss and 0-1 for my san mai, and have no experience with 304/15n20.
Click to expand...

Tom, just for my clarification, when you say "Immediately after welding..."

Are you referring to immediately after arc welding the air tight billet, or immediately after the initial forge weld?
 
kuraki said:
I don't have any mechanical forging equipment yet, and I just don't have the time or desire to do any laminating by hand.

But at work, I have a 400 ton brake press, and flat dies.

I'm thinking of hauling my forge in, TIG welding up a 304/15n20 sandwich, and squeezing it together in one shot. Maybe draw it out a bit as this press is just as fast as most forging presses.

If I can encapsulate the entire billet with the flat dies, assuming I got a good heat, wouldn't this have a high probability of getting a good weld?
Click to expand...

Why 15N20, why You do not use some better steel? At the press I successfully welded 52100 and 2x5160 , and I used borax .And this is the first time I did it .Now I intend to make another one from some of 400 stainless steel series and in the middle 1.2519 steel ..........
 
What I mean by "immediately after welding", I am referring to arc welding or tig welding the billet air tight. As soon as the billet is arc welded, stick it in the pre-heated forge.
I have tried to post some pictures of my work, but for some reason this site won't upload my pictures.
I hope you will let us know how this turns out.
 
If you want to send them to me, I can upload them to my hosting site and post them.

Is the purpose of getting it right into the forge to avoid stress fractures from the weld? Or something else?
 
I got the idea of getting the billet in the forge as soon as the sides are tacked up from Ed Caffery. If I remember right, the idea was if there was a pinhole in the tack welding , when the billet cooled oxygen would be pulled in and harm the welding.
 
Gotcha. Logistically that will be tough but I think I can do it. (welders on one end of the building, press on the other) We have one on a cart I could pull up there and do it all in the same area.
 
Here are the photos Tom wanted to post:

mw3ara.jpg

2v824bm.jpg

339m8f5.jpg
 
Thanks for posting my pictures. I don't know why, but when I "go advanced" and go to "manage attachments", the BF program will not let me upload pictures. My pictures have been re-sized and I never had that problem before.
 
So what are we looking at Tom? Other than some gorgeous knives, details I mean.
 
The blades were made of 1/4" 410 ss with a 1/4" piece of 0-1 sandwiched in between. The middle picture was the first blade I made. The other two I used 1" round bars to put a ladder pattern in.
I had heard that a person couldn't do much forging to shape with san mai, without it de-laminating, but my experience was different. I was able to draw it out and forge to shape.
I think the 410ss made the difference.
Plan to use up a new 36 grit belt getting the forge scale off. I don't know why, but the 410ss forge scale was the toughest forge scale I have ever encountered.
When the weather gets cooler I plan to make some more.
 
Do yourself a favor and stick the billet in a bucket of sodium bisulfate (ph down) overnight. It will dissolve and/or soften the scale ... leaving pretty much bare and clean metal.
Rinse well in running water while scrubbing with a stiff brush. Rinse again and wash with soap and water. Wash your hands, too. Rinse off your tongs that you put in the bucket, too.

About two pounds of SB to a gallon of water is good. Use a drywall/pickel bucket and just put the lid on when not in use. Mix 10# of SB to 5 gallons of water. It will last a long time. If it slows down, add a cup of SB.

SAFETY:
Work outside and stay upwind of the bucket. Fill the container with the water. Slowly add the sodium bisulfate as you stir. It may release a smell, so don't breathe the fumes. Once all has been added, stir a while more and the solution is ready to use.
 
I'm wondering if I dare passivate a 304/xxxx carbon blade, or if the nitric acid will cause hydrogen embrittlement in the carbon edge.
 
​
Tom Lewis said:
What I mean by "immediately after welding", I am referring to arc welding or tig welding the billet air tight.
Click to expand...

not trying to hijack this thread, but is welding air-tight really necessary? the last 2 billets I did about 6 months ago were without flux and only tacked. Surfaces were ground very clean and I did soak at heat for a bit...Did I just get lucky??
 
weo, if you are talking about san mai with stainless outer layers, air-tight is pretty much the way to go... are you saying that you had a ss/carbon billet cleaned up well, tacked only, and welded well with no flux and a fuel-rich forge? If that was reliable, it would be a good way to go, as well...
 
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