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A few suggestions beyond what has been said here.
First, if you want to minimize cracking blades.
Buy some sort of industrial quench oil.
If you are not going to use a magnet or a thermocouple then train yourself to judge quench temp by eye.
The color to me looks like a harvest moon.
A medium bright orange with no shadows in it.
The problem with looking into a lit forge is that your going to have a hard time judging because of the light that the forge itself is making.
This is another reason to use a pipe.
Because there is not just decalesence there is also recalesence.
So not only can you watch the transformation during normalization where the light in the blade, starting at the edge, darkens and spreads over the blade and then there is a brief brightening of the light in the blade before it drops to black again.
In Recalesence you can watch the shadows disappear from the steel while it is heating up.
Because the the edged is thinnest it will generally heat up fastest, thus making it into solution before any other part of the blade.
You could quench at this point without clay and get a hamon. Probably in any steel, maybe not a pretty one but there will be a transition zone between martensite and pearlite

I have been told the Japanese, in days yonder thought the shadows were the Kami of the blade, the spirit if you will.
And they can control the heat to the point that they can quench when there is shadow dancing around the clay line thus allowing another condition to effect the hamon process.
As far as breaking blades.
We are creating tremendous stress in the steel in the hardening process. This is why normalization is so important.
Like Alan and others said, you need to know the difference between normalization and annealing .
After at least 3 normalizations an annealing cycle is a good thing to do also, and based on a conversation with Roman Landis one of the metalurgists at Audi told me its pretty much industry standard and the way he heat treats his blades.
He could give the science behind it.
I'm just not that educated.
Beyond that, when you quench, martensite takes time to grow in the steel.
So if there was no clay a chance of a crack is in the transformation after it comes out of the oil.
But having clay on the spine causes a ton of stress in the thinnest part of the blade.
Because you have slowed the cooling rate for the spine the edge cools faster which causes the bend in the blade.
That bend stretches the edge, the thinnest part of the blade.
Which is why in my estimation you get a line of cracks like your blade where the steel is literally being pulled apart.
They tend to be uniform, spaced kind of evenly and about the same height.
Another thing to note is that while there are water hardening steels.
The W series, 1095 hahaha.
Modern high carbon steels really aren't meant for water quenches.
What the Japanese are using is a very simple steel and as far as I understand it any steel like this WILL NOT harden in oil.
And has to be quenched at a startlingly hot temp.
So treating modern steels meant to be heat treated in an industrial quench oil like historic steel is going to add to the curve of loss of blades.
The Japanese loose something like 25% of their blades to cracking in heat treat and that steel is specifically meant for water and they are very familiar with the process.

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I did not read in depth on everyones posts, but when I normalize I keep a magnet handy to check the blade then let it cool back down to magnetic and back into the fire she goes...3x

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I did not read in depth on everyones posts, but when I normalize I keep a magnet handy to check the blade then let it cool back down to magnetic and back into the fire she goes...3x

You'll get better results if you let it get a bit colder between re-heats. Room temp would be best, but at least down to black (definitely below 1000). Not to say that that isn't good enough, just that for a few more seconds of cooling and re-heating you could get better.

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  • 2 months later...

Ok, I've been working on a few more blades from this steel and I've learned a few things.


Firstly it doesn't seem to like water at all, a recently finished Bowie with a hamon was hardened in an interrupted water-oil quench and ended up with multiple cressent hardening fractures in the point, other than that it faired quite well and has an attractive hamon. I believe this is due to the high manganese content (possibly higher than standard 1060)


Second, in spite of the high manganese content this steel will deferentially harden with clay quite easily, I hardened two blades this week from 1475*F into warm transmission fluid and they both show promising hamon's.


Now as far as the performance of this steel. it seems to have good wear resistance, during hand sanding when compared to 5160 hardened at 1550 and tempered at the same temp(400*F) it seemed to take a small amount of extra effort and would slide the sandpaper unless fresh. also this steel seems to be harder than 5160, when tempered at the same temp a file seems to bite easier in 5160 than this steel. And in tests conducted with the cracked blade I had mentioned before it showed good edge retention when chopping into fairly fresh ash.

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  • 1 month later...

I'm working on a knife now that was made from an anchor. It's ugly (my first completed knife) but I'll do some tests and put them up on this thread.

Edited by Ryan Hobbs
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  • 1 year later...

Found a supply of anchors myself (Safelok I type) and am conducting a number of tests on them, using very small kwaiken style blades. I did a ton of research into them and they look to be pretty safely 1060, however I found a chart that narrows it down to 2-4 very slightly different types, with the main difference in between them being Manganese content (ranging if I remember rightly from .17-.95% or so). 

So, test results. So far I'm not touching the subject of hamon, but I'm quite sure I'm getting some autohamon in a few. 

Forged seven blades out, extremely small kwaiken styles, spine thickness a tad above 3/16" and edge thickness about 1/16". First tests were for quenching itself, plain water. Three blades were cracked, however they were not standard perpendicular edge cracks but rather went lengthwise along the spine. Experimenting narrowed it down to overheating: darkening the room to supplement my magnet fixed this issue. So far my go-to is interrupted quench: 3-4 seconds in water and finish in warm canola. Yes I'll get Parks one day. However, despite interrupted quench resulting in safe results, plain water worked very well so long as I didn't overheat, which actually surprises me, especially as the edge is very thin. My theory is that the Safelok I anchors are very low manganese. There is also the possibility that because the blades have very low surface area, there's far less stress over the blade, which works for me. I also emailed the manufacturer asking for the technical data. It's unlikely I'll get a response but you never know. 

I haven't documented my results in plain canola as of yet, but from a few earlier blades it didn't seem to get quite glassy, whereas water did it every time.

One blade I clayed up with Rutlands and did an interrupted quench (3-4 seconds in water), resulting in no hamon activity. I normalized and tried again, this time with roughly one second in water before canola. This gave me an autohamon. Not much activity but an autohamon nonetheless. 

On to tempering, my first blade I tempered at 300 for three hours. I shot low on purpose, just making sure I have a base testing point. Edge retention was incredible. Hammered through walnut, brass rod, still hair shaving. Got about an eight inch through a bar of iron before it chipped a chunk out of the edge. Concrete toss test was just plain fun, made sure to get a good number of tip first into the cement. Nicked up the edge of course but no snapping of the tip, and nothing that couldn't be repaired with five minutes of sharpening. Very please. It didn't do so well on the bend test, absolutely no flex before breaking, but it did take some fair effort before that happened. 

Tempering the second blade to 350 F, will conduct tests this afternoon. 

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Sounds good, and fun!  Did you see any silicon in the specs you found?  If so, and it's about around 1.0 -2.2%, you've got 9260.  Great stuff for toughness. And with low Mn it will take a hamon.

The ASM heat treaters guide mentions it is close to S-5 for shock resistance too.

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Not sure yet, the best specs I could find was a selection of common steels used for the type of clip I'm researching. Four different steels, no way as of yet to narrow down which one it was except for (and this is still only theoretical) the fact that I didn't ping anything in a water quench. They're all in the standard .55-.65% carbon range though. Thanks for the info! With a bit more experimenting, I should be able to narrow it down. 

Or, I guess, get it tested, but that's no fun. 

In any case, I'm testing for the ideal tempering now, but would 9260 take a slightly different temperature from 1060 or is it close enough to warrant roughly the same heat treat?

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Interesting! I've been meaning to put up my results, but the Army is great at keeping me busy and away from my forge. 

I came up with results very similar to you Caleb! I made a 14" blade  Frankish seax. I put it through three normalizing cycles and then quenched blade section in cool water and got a messy hamon out of it (I left the top half of the blade out of the water). The steel hardened very well, same as you. I annealed it at 450 for 3 hours, and  then tried to fix a slight warp that formed during quenching. Unfortunately two cracks formed, each about 3/4 of an inch long, lengthwise down the spine about 3 inches from the beginning of the tang. One began where the other ended. The spine at that point was about 5/16 thick and didn't get quenched, so I was surprised that a crack started here.

Perhaps quenching the entire thing or annealing it differently would help?

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By Annealing do you mean tempering? My bet is the cracks formed during the quench itself and not when you tried straightening it; breaking the blade will reveal if this is the case or not. If the crack formed during the quench, when you break it you'll see the inside of the crack and it'll be colored by tempering colors. 

My best theory as to why the lengthwise cracks form is to too quick of cooling (and "shrinking") rate of the surface: I've had this many times and never had I had a crack go all the way through from one side to the other. I'm pretty sure that overheating the blade before the quench is the culprit. Try heat treating another one as close to critical temp as possible? That might do it. Quenching in the dark to more closely monitor heat should do the trick.

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Ah, yes, tempering, my bad.

There were no cracks after the quenching, and I heard it crack while I was trying to straighten it. Maybe the cracks were formed in the quench and didn't come to the surface until I tried to straighten it?

I have a few more knives that I've forged to shape, I'll have to try a lower quenching temp!


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Hm, now that's interesting. I guess the only way to find out for sure is to break it and take a look at the color of inside of the crack.

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The manufacturer, Pandrol, responded to my email! 

"Many thanks for your email. Unfortunately this information is part of our IPR and we are unable to release it. 

I hope your project is a success."

So dead end there. Oh well, I'm getting close to perfecting my process. Tempering at 350 F gave me about a 30 degree bend before snapping. 375 should give me what I want for a kwaiken, I'll probably be looking at 400 for mid size and closer to 420 for larger blades. 

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  • 2 months later...

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