1018/26c3 San-mai question

R

running bird

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Sep 29, 2015
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Over my weekend I started a billet of 26c3 San-mai with 1018 cladding. The 1018 is about .25” thick and the 26c3 is .200” thick. flattened and cleaned all surfaces, fully welded the seams around the billet so I could avoid using flux. I don’t have a thermocouple but I heated to a bright/light yellow color for the welding heat. How much “squish” should I expect to feel under the hammer?

I’ve never hit 1018 with a hammer at that heat before but that first hit with the hammer caught me off guard with how soft it felt. Not to the point of crumbling or showing any cracks but it has me worried about how the whole thing will draw out when I get back to drawing out on my next day with it. Am I going to have the 1018 drawing out at a different rate to the 26c3, effecting the shape or the welds?

As I started drawing out I used progressively lower temps until I was at a normal forging temperature. I normalized once I stopped for the day but should I cycle the billet after I grind the edges to check the welds, or just carry on with forging after I check them?

Kevin
 
(With the caveat that I'm new at this too)
Yeah, I've found when hand forging the outer layers move more easily. It shouldn't affect the welds, but does seem to lead to some mushrooming around the edge. More aggressive drawing might help, but that would risk moving the core steel in ways you don't want.

And yeah, mild steel is squishy
 
I had a 3 day weekend so I got 2 days of working on this billet. The welds looked good before drawing so I just sent it with the forging.

It’s taking me a good while since I started with a thick billet and I forge slow. Is there a point where I can have too much carbon migration from forging?

Since I’m up to about 7hr total of welding it together and drawing it out, I see myself needing at least another 3-4hr until I get close to my final thickness… I’m very slow lol
 
You won't get carbon migration ... because it is carbon diffusion.

It will happen to some degree with many heats and long soaks. It is what it is.

Don't worry about it, it isn't the same as mixing chocolate syrup and milk and ending up with a chocolate milk.

To quote an old friend (now passed) from Shop Talk -
"Caribou migrate, carbon diffuses " .... Mete
 
Stacy E. Apelt - Bladesmith said:
You won't get carbon migration ... because it is carbon diffusion.

It will happen to some degree with many heats and long soaks. It is what it is.

Don't worry about it, it isn't the same as mixing chocolate syrup and milk and ending up with a chocolate milk.
Click to expand...
My bad mixed up my terminology there ha ha. Got it, thanks. As long as it I’m not racking up weeks of time drawing out this one billet I won’t worry about it
 
You said you have been forging and welding this billet for 7 hours! That is a long time. Are you sure you are fully heating the bar all the way through. I would expect a .70" billet to reduce by half in a couple hours at most.

I suspect you are not fully heating the billet through the core.

What size and type hammer are you using?
What type and size forge are you using?
How long is the billet in the forge each heat?
How many total heats have you done in the 7 hours forging time?
How much thinner does the billet get each heat?

Remember that the "Final Thickness" will be thicker than the final blade by a good bit. You will have a good layer of scale to remove and then grind clean. If you want a .25" thick bar of san-mai, stop at .35" and clean it up. You will remove a good .05" per side.

Soaking the blade overnight in a Ph-Down pickle will remove the scale easily. In the morning wash it off well and scrub under running water with a wire brush.
If doing multiple forging sessions, a soak overnight between sessions helps. Forge scale is HARD stuff.
 
Stacy E. Apelt - Bladesmith said:
You said you have been forging and welding this billet for 7 hours! That is a long time. Are you sure you are fully heating the bar all the way through. I would expect a .70" billet to reduce by half in a couple hours at most.

I suspect you are not fully heating the billet through the core.

What size and type hammer are you using?
What type and size forge are you using?
How long is the billet in the forge each heat?
How many total heats have you done in the 7 hours forging time?
How much thinner does the billet get each heat?

Remember that the "Final Thickness" will be thicker than the final blade by a good bit. You will have a good layer of scale to remove and then grind clean. If you want a .25" thick bar of san-mai, stop at .35" and clean it up. You will remove a good .05" per side.

Soaking the blade overnight in a Ph-Down pickle will remove the scale easily. In the morning wash it off well and scrub under running water with a wire brush.
If doing multiple forging sessions, a soak overnight between sessions helps. Forge scale is HARD stuff.
Click to expand...
By 7hr I that’s the time the forge was on for. When I forge welded the billet it was about an hour between that and a tiny bit of drawing out. Then 3hr each for 2 more days (one of those I was kind of messing around with different methods of drawing it out). As for Total heats I have no idea, I have a counter mounted on the forge cart but I never remember to use it.

I’m mostly using 2lb hammer and a 3lb cross peen hammer. I’ve got very little experience drawing out billets this thick so I’ve kinda been experimenting with how I’m doing it. I was also trying out the guillotine I just finished, using the 3lb hammer.

I have a 2 burner oval shaped forge, but when I’m working with just one piece in the forge I only use one burner. I could probably bump the pressure up on the regulator a bit, was running it low to try and save some on fuel but I have a feeling that is making this take longer (and wasting more fuel…lol)

Right now the billet is just under .5” thick, but I drew the length out to ~6” and brought the width in closer to 1”. It started as 4”L,1.25”W, .75”H.
 
I’d say you are using too light of a hammer and not getting good movement through the material, a 2-3lb hammer on 3/4” stock is mostly moving the surface and not really moving material effectively. I use a 6lb hammer when drawing thick stock down thinner if I’m working by hand, learning to swing heavy hammers is going to be a necessity if working down thicker material by yourself. Stand close to the work and when picking up the hammer rotate the head up first so the hammer is vertical then lift up over your head and drop the hammer on the downswing with a slight flick of the wrist like cracking a whip. If you try to pick the hammer back up in an arc it’s much heavier and if you are only swinging from shoulder height you aren’t getting a lot of force behind each hit making you work harder for longer. It helps to pick a spot on your anvil and strike the same spot and move the bar to be where you want to hit versus trying to hit different spots with the hammer and moving each hammer strike.
 
If you have an anvil with a horn, use it to draw.
If you have an anvil with a Hardy hole, consider a metal version of a bench dog that’ll hands-free your billet on the face so you can beat it with both hands on a sledge. (saw that on YT)
 
Use the 3# to 4# cross peen to draw the billet. Work up and down the billet and flip over.

A good set of drawing/fullering tools can be made from a 3" long piece of 1" round stock and any cheap 3#/4# cross peen hammer.
Gring the round stock flat on one side to roughly half round and securely welded to a square stub that fits the hardy hole.
Make a matching drawing hammer by grinding the end of a cross peen to the same radius as the 1" round stock.
Drop the hardie in the anvil and hammer the billet with the hammer, aligning the two curvatures. It may take a little practice on some 3/4" plain steel to get the hang of it, but it will draw a billet very fast once you get it down.

Another simple device is a 1/2" to 3/4" spring fullering tool. Take a 18" piece of round stock and bend it in a tight "U" like a giant bobby-pin. The bigger the loop/bow on the curved end the springier it is. The bottom arm should be flat to the anvil face. Harden and spring temper the round bend.
The fullering ends should be just a bit more distance apart as the billet you are working. Weld a hardy stub on it about halfway down one leg. Place the work piece between the fullering arms and hammer on the top arm. A "striker" helper can wield a sledge as you move the billet through the fullers.

Guillotine fullering jigs work the same way and are really great for fast fullering of tangs and such.
 
Joshua Fisher said:
I’d say you are using too light of a hammer and not getting good movement through the material, a 2-3lb hammer on 3/4” stock is mostly moving the surface and not really moving material effectively. I use a 6lb hammer when drawing thick stock down thinner if I’m working by hand, learning to swing heavy hammers is going to be a necessity if working down thicker material by yourself. Stand close to the work and when picking up the hammer rotate the head up first so the hammer is vertical then lift up over your head and drop the hammer on the downswing with a slight flick of the wrist like cracking a whip. If you try to pick the hammer back up in an arc it’s much heavier and if you are only swinging from shoulder height you aren’t getting a lot of force behind each hit making you work harder for longer. It helps to pick a spot on your anvil and strike the same spot and move the bar to be where you want to hit versus trying to hit different spots with the hammer and moving each hammer strike.
Click to expand...
I’ll see if I can find a heavier hammer or a sledge I can cut down and give this a shot. I do have a cross peen hammer head laying around that looks like it could be a 4lb+ head, if it didn’t have a 1/2 wide hole drilled vertically through the cross peen end. Not sure if this type of head was designed with that gap in it or if someone drilled it out at some point. If I could fill and weld that hole it might have enough weight to work.

Thanks for the tip on technique too, I’ll definitely have to give it a shot. I have lots of thick stock that I’ll get around to working too so I might as well start preparing for it now


fitzo said:
If you have an anvil with a horn, use it to draw.
If you have an anvil with a Hardy hole, consider a metal version of a bench dog that’ll hands-free your billet on the face so you can beat it with both hands on a sledge. (saw that on YT)
Click to expand...
I didn’t even think of using the horn on the anvil. Mine is a little jacked up from being abused at some point in time so I tend not to use it. I don’t think there’s any amount of magnets or weights that will dampen the sound of me hitting the horn… but I’m sure the neighbors won’t mind too much.

I have a very old wrought iron hold fast hardy tool I can use as a third hand if I need to

Stacy E. Apelt - Bladesmith said:
Use the 3# to 4# cross peen to draw the billet. Work up and down the billet and flip over.

A good set of drawing/fullering tools can be made from a 3" long piece of 1" round stock and any cheap 3#/4# cross peen hammer.
Gring the round stock flat on one side to roughly half round and securely welded to a square stub that fits the hardy hole.
Make a matching drawing hammer by grinding the end of a cross peen to the same radius as the 1" round stock.
Drop the hardie in the anvil and hammer the billet with the hammer, aligning the two curvatures. It may take a little practice on some 3/4" plain steel to get the hang of it, but it will draw a billet very fast once you get it down.

Another simple device is a 1/2" to 3/4" spring fullering tool. Take a 18" piece of round stock and bend it in a tight "U" like a giant bobby-pin. The bigger the loop/bow on the curved end the springier it is. The bottom arm should be flat to the anvil face. Harden and spring temper the round bend.
The fullering ends should be just a bit more distance apart as the billet you are working. Weld a hardy stub on it about halfway down one leg. Place the work piece between the fullering arms and hammer on the top arm. A "striker" helper can wield a sledge as you move the billet through the fullers.

Guillotine fullering jigs work the same way and are really great for fast fullering of tangs and such.
Click to expand...
I had considered making one of those spring tools. The only round bar stock I have available around me and on hand is 1018, would that still have enough of a spring to it to be useful? Even if it’s just a temporary tool until I can get some medium carbon steel round bar like 4140 or 1045

Thanks for the replies guys I’ll give these all a shot and see what works best for me
 
R running bird Take a small refrigerator magnet and put it on the very tip of the horn. Check to see if it has reduced the ring. If that works for you, find a circular magnet with a hole in the middle that'll grab on that tip. (This trick was taught to me by the lead 'smith @ Centaur Forge, credit due.) It quiets my bell-like Peter Wright more than the big magnet on the side, the big chain wrapped around it or having it nailed into the stand. I don't know the physics, but it works.
 
fitzo said:
R running bird Take a small refrigerator magnet and put it on the very tip of the horn. Check to see if it has reduced the ring. If that works for you, find a circular magnet with a hole in the middle that'll grab on that tip. (This trick was taught to me by the lead 'smith @ Centaur Forge, credit due.) It quiets my bell-like Peter Wright more than the big magnet on the side, the big chain wrapped around it or having it nailed into the stand. I don't know the physics, but it works.
Click to expand...
I have 2 large ring shaped shop magnets on it and one large rectangular one I use for grinding stuck on the side of mine. I’ll try drilling out the holes in the shell of one of the ring shaped magnets so it will fit around the horn. Right now one ring is stuck to the bottom of the horn and one to the bottom of the other end (toe?) next to the hardy hole.

My anvil is also a Peter Wright (135lb) the ring really is something else without the magnets on. Thanks for the tip!
 
Had some more time to work on this project this past week. Using the technique mentioned by Josh and the biggest hammer I could find locally (4lb) it was significantly easier to thin out the billet. Brought it down to little under 1/4” in no time.

https://imgur.com/a/cpxH7pK

The 1018 looks like it ended up a bit thinner than the 26c3. My plan was to just forge the billet down and then do some stock removal. But since it looked so thin in the cladding I’m afraid the finished knife would have too much of the core exposed on the bevels. So I just opted for forging it a little closer to shape. Forged in the bevels and brought the edge to about 2mm thick before grinding

I’m still trying to figuring out the proportions for the finished knife but I’m planning on doing a small/medium sized bowie. I might forge out the tang a little more for some more length and to center it a little bit more with the ricasso
 
That looks like a nicely welded billet.

However, I still think that you may not be fully heating the billet before forging each heat. A thick billet takes a long soak to heat all the way through. What happens is you only heat the cladding hot enough and forge down the cladding much more than the core. This may have happened mainly in the early forging and continued in the second heavier forging.
You were wise to forge the bevel to shape before grinding or you will have no cladding showing except at the spine..

Let's look at the numbers:
The initial .70" billet had .25" cladding per side and a .20" core
It was reduced to .25".
Looking at the image I estimate the core is now .125" and the cladding is .05" per side (maybe less).
That means you reduces the cladding by 500% and the core by 60%
This certainly shows that the core was not getting moved in the forging heats.
The 1018 forges at 2100°F and the 26C3 forges at 1800°F. So, the issue has to be the cladding got hot, but the core was way too cold to move.
 
I’ll definitely make sure for the second attempt that it soaks at heat before I take it out of the forge each heat. Would it also help for me to start with thinner material overall? I have some ~.110” 26c3, I just have to source some more 1018 of the same size.
 
It all depends on what the final thickness desired is and how you are welding the billet.
If you are forging by hand down to .25", then what you had was about right. If you are forging to .15", thinner would save time.
If using a press, you can start with a billet only 50% thicker than needed, say .10"-.15"-.10".

Here is a rough summation of how I do san-mai:
I usually start at around twice as thick as the desired drawn-out thickness, and press weld it. Something like .125"/3mm core and .10"/2.5mm sides.
I then hand forge to a .15"/4mm flat billet.
I cut the tip off at an angle and grind a very basic blade profile (ignore the tang for now)
Next, I start forging distal taper, pull down the bevels, and thin the edge. Always work from both sides evenly as you go. If you don't forge in te distal taper and bevels to at least 75% the san-mai line will not end up evenly spaced as you approach the tip when you finally grind the bevels to shape.
NOTE - A smooth faced 1.5Kg hammer is perfect here. I like my Hoffi (Czech style). Sand the face smooth to at least 220 grit before final shaping and it will make smoother bevels. Make sure the edges of the face are "broken" by a slight chamfer.

I grind the edge flat all the way around the blade and check the core centering with a quick FC dip. (125-grit is fine for all the checking steps)
If it looks good, I shape the tang and refine the blade shape on the grinder. I clean up the sides to remove the major forging marks and expose the san-mai clearly (it is usually multi-layer or suminagashi*)
At this point the blade has a basic shape, the spine is around .125"/3mm at the ricasso/tang, and the edge is around .03"-.05"/1-1.5mm.
If the core and sides look OK, I grind a quick edge bevel at around 10-15 degrees to see the line where the san-mai meets the core and check the core position better.
If there are adjustments to the core position needed, I forge it to center making a bacon like edge to correct it, grind flat, and check again. If the san-mai ends up too thick, the blade gets ground a lot thinner than planned. This is usually a good thing in a kitchen knife.
If no adjustments are needed, I flatten the edge, normalize/thermal cycle the blade, do the HT, and finish the grinding post HT.

* Suminagashi is when you make damascus and use it as the san-mai cladding.
The damascus (or any san-mai cladding) does not need to be hardenable, and things like 203-E/1084/15N20 make a good mix
Adding a thin strip of pure nickel between the core and the cladding creates a faux hamon effect once forged out that looks great.
 
I had some time off from work so I’ve been working on this blade a bit more. Got the rough grinding done, finished to 120grit then went in for the heat treatment. 1475° for 10min and quenched in parks 50, started with a 300° temper for 2hr incase there were any warps I needed to fix.

Just got it out of the oven from the temper and noticed that the 26c3 core split at the spine during the quench I assume. The crack is straight down the spine, not even a delamination along the weld just straight down the spine.

https://imgur.com/a/4Lk7viT

Everything else held up great at least, no delaminating along the edge and no cracks on the edge (that I can see at least). Maybe on the next one I should round the spine? I tried to make sure there weren’t any sharp angles in the geometry of the blade to try and avoid stress.

Forging the bevels did help make the best of the issue with the cladding being too thin by the time I was done forging. While I was rough grinding the blade the transition between the core and 1018 was still decently close to the edge

https://imgur.com/a/00lk8kO
 
Too hot and too violent a quench.
Try quenching IN-1-2-3 ... OUT-1-2-3 ... back in the quench tank until cooled.

I have several of those split blades in the reject bin, so don't feel alone in the anguish. On ones that looked like yours, I have clamped the blade tight between metal plates in a vise and TIG welded the crack shut to salvage the bade for personal use or for friends. Sometimes it was unnoticeable.
 
What was the condition of the steel before hardening and tempering? Normalized, annealed, other? Are you using a forge or a furnace to heat treat?

Hoss
 
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