Forging a brush sword, a few questions

I

Ian Fifelski

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Oct 4, 2017
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Afternoon Gents,

I am making a brush sword for in the woods and I am forging it out of some unknown steel.
I took a piece from the bar and did some practice/fun forging and will heat treat this little piece to see what it will harden to.

Question
1: When I was forging the little test piece I noticed fine bubbles and pitting when reheating it after a couple of heats. It was very hot when this started happening. I am not sure if this is normal for very hot steel?

2: What angle of backwards curve do I want so the blade will be near straight? The blade will be roughly around 2 feet long and will be bringing the width from about 1 1/4 inch to 2 inch. The bar is 1/4 inch thick. I have actually never forged a blade longer than 4 inches so not sure how much it curves from forging bevels.

3: For future forging, what is a normal carbon loss from forging? I am pretty slow at this point and have a small anvil like object to do all my work on. Would it ever be enough to change the heat treat?

Thanks all,
Ian
 
None of you questions can be answered ... because it is mystery steel. The worst steel for a sword is mystery steel. I really recommend you set this blade aside when done forging it and use a piece of known steel to make a new sword. 1070/1075 and 5160 both make excellent bush swords. Aldo has 1075 in four thicknesses from .187 to .350". He is often out of some sizes, but currently, he has .187X1.25 X48" for $25, and .187X1.5X48" for $29.

1) Your "bubbling" could be you burning the steel by getting it too hot, or it could be a coating on the steel, or the metal itself ... no way to know without seeing it ... and no way to know with mystery steel.
2) The amount of negative sori will need to be determined by practice. Your quench medium, the steel, your HT method - all these affect sori. If doing an oil quench, you don't need any negative sori. Just forge to the shape desired. I leave a little extra width in the blade to adjust the curve on the grinder after tempering . With a brine quench, I use a little negative sori to keep the blade from becoming too curved in yaki-ire.
3) Forging loses some carbon, but it is insignificant unless you are greatly overheating or burning the steel. The surface gets decarb, but that is ground away in the final shaping and sanding. If you start with 1084, it is still 1084 under the rind ( the layer of scale and decarb formed in forging).
 
I totally agree with avoiding mystery steel. I should have mentioned that this was more of forging practice with a possibly usable brush hacker in the end. I finally got itc-100 on my forge to heat faster and hotter and I wanted to get some experience moving metal before using a known steel. I have 3/8in 1075 just for this purpose that I plan on using for another brush sword and bowies after I get a feel for things with free steel. Oh, and speaking of steel, I have a few springs from our 1965 ford galaxie. Most coil springs are 5160, correct?

I think the bubbling was the steel burning because I let it soak for a particularly long time that heat. I have heard of burning but never have actually seen it.

I believe the steel is a medium carbon steel, so I plan on quenching in water.
 
I have been working on this for a little while. I got it all forged, ground, normalized and heat treated. After heat treat checked with a file, hard. There was a warp near the tip though.

I put it in the oven at 450 for an hour and after that time clamped it to some straight angle iron still hot. Put it back in for a half hour and then put an about 1/8in shim in to help the warp some more. The one last twist broke 3 inches off the tip. Grain size looks great though. :)

I know I am hard to help because I am using mystery (misery?) steel but does my story sometimes happen? I would think after an 1 1/2, 450* temper it would toughen up a good bit. I clamped the tip down bending it about 5/16in and where it broke was probably 1/4in at its thickest. From this info should I temper just longer or should I go hotter? I currently have it in for another hour.

Thanks

ETA: I am tempering again because what is left is still usable if I clean up where it broke.
 
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I did the second hour temper and used the tip to see how tough it was and I broke the first half inch off the tip prying at two thin boards nailed together. Still at a loss.
 
OK, first off, straightening is either done between 900F and 400F immediately after the quench, or after the second temper. It is still somewhat brittle after the first temper. Everything else you did sounded right.

Yes, sometimes the blade breaks when straightening. This can be bad steel, bad technique, or bad luck. It happens to all of us.

Mystery steel may have flaws and microscopic cracks that will cause breakage after hardening. I really recommend using a known steel.

Fellows - Barefoot boy is in PA. There are a lot of you around his neck of the woods. Maybe one of you can give him a length of 5160, 80CrV, or 1084.

Barefoot - If no one around you offers help, send me a PM or email and I will send you some good steel for your sword.
 
Like I said above, I have steel for making this sword, some of Aldo's 1075. Thank you though. I would always recommend a known steel as well, going against my own rules.

This was a forging practice for when I use a known steel considering I have never forged something longer than 4 inch blade. I am glad I did this because it did not turn out the shape I was going for. Now I have a better feel for moving hot steel and fixing warps. (and maybe a chopper for the woods)

So I guess I will give it another hour at 450* and see where its at.

Thanks
 
What was the different shape that you got from what you wanted?

If it was that there was a big upward curve, that is from not bending the bar downward before forging the bevels. As the metal gets pushed down to make a thinner edge, it also moves sideways., making the edge longer than the spine ... and thus making the blade banana upwards. By bending the bar in a reverse banana, you allow for this curvature, and end up with a straight blade ( or the desired curve). If you try and straighten down a blade that has the bevels formed, it will usually waffle the edge. Little adjustments can be done, but big errors are a real B!t@h to fix.
 
I forged the backward curve and had the cutting edge flat with the spine dropping down like I saw in Nick Wheeler's WIP so that turned out ok.

The problem was with the tip, handle and plunge line. I didn't thin the width of the bar enough and the tip got really wide. For the handle I actually broke it from accidentally hardening it. I was cooling it down in water after forging and with my shade 3 forging glasses I couldn't see it was hot enough to harden. So when I was working on the blade I hit near the handle and it broke because it was brittle from hardening. Luckily it broke just far down enough I could still make it into a handle, though it wasn't near the shape I wanted.

When I was working on the plunge, I hit the handle a couple of times so it isn't flat which is going to make it fun to put scales on. Maybe shims and a bunch of jb weld.

So I learned a deal!
 
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