Full billet thickness water quench

[musicman980]

What disadvantages are there to water quenching a shaped, but unground 1095 or similar steel billet, other than it’s more to grind off after HT?

This would be to lower the risk of cracking while producing a hamon on a 3/16 - 1/4 thick billet.

Thanks!

 

[Stacy E. Apelt - Bladesmith]

You will get a poor (if any) hamon after removing the extra steel.

You need to at least pre-shape the bevels. You can leave a thick edge to prevent issues. I leave the edge about .040"

The ways to prevent cracks and warp on yaki-ire blades are:
Shape the blade very evenly from both sides.
Sand to a flawless 400 grit. Make sure the edge and spine are very smooth, as any nick or deep scratch can be where a crack starts. Avoid any hard angle. Slightly round the spine and edge.
Use a wash coat over the whole blade, and a fairly thin clay coat for the hamon ( about 1/16" to 3/32" thick).
Have a straightening board ready in the vise to straighten warps and twists immediately after removing from the water.

 

[musicman980]

That's perfect, will do.

I was actually planning on making a yanagiba, and leaving the hamon entirely above the shinogi, meaning not much if any grinding done in that area after HT. Would a full thickness billet, rounded edges and everything else you said, have a much lesser chance of cracking than if I preground the bevel?

 

[John mc c]

On a yanagi you will have little hope of preventing warping or cracking if you grind bevel before ht

 

[Stacy E. Apelt - Bladesmith]

Warp and cracking are just part of learning yaki-ire. Some ( OK, most) will warp. Some will crack.

The hamon will almost always form where the blade is thinning, so trying to place it in the thickest part will be difficult to nearly impossible. This is because the cooling rate is faster in the thinner steel. As the metal rapidly drops during quench, the thinner steel makes it past the pearlite nose and stays as supercooled austenite … which a few seconds later converts into martensite. But, the thicker and more clay covered steel lags behind and becomes pearlite. The area where these two processes meet is a mixture of structures and crystals which form the hamon.

The biggest thing you need is a very low Mn (and low alloy) steel.
Use a large volume of brine.
Make three or four identical profiled and pre-beveled blades to quench. This way you have back-up blades. Set the extras aside and do only one at a time so you will learn how to apply the clay in the best method and get used to the brine quench. Doing all of them at once will only teach you how to curse in Japanese. After the first is done tempering, clean it up enough to etch and see the hamon (even if it breaks/cracks). This will give you information on applying the clay on number two, etc.

 

[musicman980]

On a yanagi you will have little hope of preventing warping or cracking if you grind bevel before ht

Warp and cracking are just part of learning yaki-ire. Some ( OK, most) will warp. Some will crack.

The hamon will almost always form where the blade is thinning, so trying to place it in the thickest part will be difficult to nearly impossible. This is because the cooling rate is faster in the thinner steel. As the metal rapidly drops during quench, the thinner steel makes it past the pearlite nose and stays as supercooled austenite … which a few seconds later converts into martensite. But, the thicker and more clay covered steel lags behind and becomes pearlite. The area where these two processes meet is a mixture of structures and crystals which form the hamon.

The biggest thing you need is a very low Mn (and low alloy) steel.
Use a large volume of brine.
Make three or four identical profiled and pre-beveled blades to quench. This way you have back-up blades. Set the extras aside and do only one at a time so you will learn how to apply the clay in the best method and get used to the brine quench. Doing all of them at once will only teach you how to curse in Japanese. After the first is done tempering, clean it up enough to etch and see the hamon (even if it breaks/cracks). This will give you information on applying the clay on number two, etc.

Thank you for the advise, guys. I’ll certainly use it.

Perhaps I wasn’t clear, or maybe you’re already two steps ahead of me. The hamon shows up where the blade thins, I can get that, but this blade would be the same thickness from spine to edge, except for the clay of course, so no thinning whatsoever. 3/16 spine, 3/16 edge.

Heck, I could even pump out back up blades even faster with no thinning done.

 

[Britt_Askew]

Perhaps I wasn’t clear, or maybe you’re already two steps ahead of me. The hamon shows up where the blade thins, I can get that, but this blade would be the same thickness from spine to edge, except for the clay of course, so no thinning whatsoever. 3/16 spine, 3/16 edge.

Go back and read the first two lines in the second post

 

[Stacy E. Apelt - Bladesmith]

You aren't getting my point. If the bar is all the same thickness, it will be harder to get a good hamon. and harder to place it where you want. Add to that the fact that when you grind away a good half of the steel on the bar in forming the bevels and finish sanding, the hamon will also be largely ground away. The only real way to learn how to move the hamon up and down is to experiment on identical blade blanks with basic bevels. By changing the clay thickness and position, and varying the austenitization temp, you can gain some control. All that said, the final hamon will usually be a bit of a mystery for your first 100 or so hamons.

Now there is a way to get the line to move down from the spine. It will be a temper line, not a true hamon, but for your needs, it may work as well.
Harden the whole blade as normal with no clay. Temper at 400F as normal. Sand to a quick 400 grit. Then, using a small torch, draw the temper line down from the spine. Heat the spine edge slowly and watch the yellow color walk down, followed by a deeper bluish color. Holding the 1/4' above the edge in a shallow pan of water while drawing the spine is a good idea. Dunk blade in the water as needed to stop the line when it gets to the point you want. The temper line will be somewhere between the blue and the yellow (usually a brown color). Make the colors form a wavy line by heating every 3/4" or so, and not going in a continuous sweep down the spine. You will quickly get the feel of how to make the line undulate. When done, sand the blade and etch. If you like it, finish the blade and etch again at the end. If you don't like it, re-HT and try again.

 

[musicman980]

Go back and read the first two lines in the second post

Again, I was hoping to have this hypothetical hamon in a place I would not have to grind after HT, where no extra steel needs to be removed. No alteration to this hypothetical hamon. Thanks for your input.

It just seemed that every post except the last one assumed that I’d be doing some grinding before the HT.
Even post #5 “So trying to place it in the thickest part will be difficult to nearly impossible” I’m thinking my billet doesn’t have a thickest part, it’s all the same thickness, so how does that directly apply?

If the bar is all the same thickness, it will be harder to get a good hamon. and harder to place it where you want.

Now THAT answers my question about a billet of a consistent thickness. I can’t thank you enough, Stacy.