1095, Mystery Hamon, HT ? & assumtions

Josh Dabney

Josh Dabney

Moderator
Lets start by having a look at what we're taking about here.

SSBowie016.jpg


Lousy pic, but it does show the hamon.

Blade was ground to approx. .010 before HT. Instead of leaving extra "insurance meat" on the thickness of the blade I left it on the height leaving approx. 1/16 to be ground off after performance testing.

Ht process-

Coat blade with anti-scale wash coat.

This is not the powder kind. It is the anti-scale available from Brownells. I dillute the antiscale with hot water. Approx. a few tablespoons worth of water then dip small fantail paintbrush in the anti-scale and mix to what is still basically the consistancy of water.

Clean blade with acetone (thanks Joe Mandt for that tip) then heat with a heatgun and paint a wash over the entire warmed blade. This ends up an extremely thin coating but it's enough to prevent scale.

Put blade in Evenheat when temp reaches 1400 degrees. let come up to 1475 degrees then a 5 minute soak.

Remove and quench point down into a coffee can of canola oil. :eek:
*I am aware that this is not the ideal quench tank or meduim for 1095*

Temper 2 hours 2 times at 400 degrees.

Shapen up blank and performance test edge with chopping seasoned oak 2x4 and brass rod test the entire length of the edge several times. 2thumbs


No attemp was made at getting a Hamon on this blade at all.

This is my interpratation of what I "think" this blade is telling me.

Cross section plays a large roll in quench speed.

As is common knowledge- Canoloa oil is an insuffient quench speed for 1095 in all but the thinnest cross sections. Like 1/8" or under.

ASSUMTION- I have what is basically the same HT that I would have if I clay coated and quenched in Parks #50.

Just because this quench produced a nice and active hamon does that tell me that I have the same properties in my blade as a blade quenched in a faster medium ?

I am by no means advocating this as a proper way to HT 1095 blades and do realize that attempting to get a hamon with this method may or may not produce the desired result and little to no control over the hamon will be possible.

I bring the dead horse of 1095 quench up yet again because I was shooting for a non-differetial HT on this blade so now I'm not really sure if I'm interpreting what this blade is telling me correctly.

What it's really saying is get a proper quench tank and the Parks, LOL.

Thanks to anyone who shares an opinion on this subject !

-Josh :D
 
Cross section does play a big part -- you can get a beautiful hamon in a full flat-ground blade with a full quench. :)
 
Josh, my granny used to tell me not to "look a gift horse in the mouth".
But seriously, I think you are on to something with the idea of of the combo of thicker cross section and oil.
Good looking knife.
 
As you know 1095 is a shallow hardening steel. One would expect that on quenching that the blade would have a jacket of martensitic steel around a core of pearletic steel, in actuality, that is not what happens, according to John Verhoeven in "Steel Metallurgy for the Non-metallurgist". What you are left with is a thickness of martinsetic steel to twice the depth of hardening at the edges and cornes of the spine. That is to say that if a blade, under specific conditions, only hardens to 1/32" the blade will form martinsite up to where it is 1/16" in thickness. Thicker than that and it will form pearlite. That leave the maker with the same effect as clay coating the spine of the blade to retard cooling in the quenchant. The problem with this method is that it is dependant upon grain size with large grain size promoting depth of hardening. If the grain is too large the blade will harden all the way through besides being more brittle. If too small then you end up with a tough blade with just a thin rim of martensetic steel around the rim of the edge.

Doug Lester
 
Thanks alot for the info fellas.

Doug- If I'm translating this info correctly then what I have is this-

Martinsite from the edge up to the hamon. (thin enough to be Martinsitic)

A mix of martinsite and pearlite which is the "activity" (the borderland)

And Pearlite in the area above the "activity" (too thick to form martinsite)

Using the the measurments for depth of hardening from your example the measurements would actually be taken from each side of the blade (????). Meaning 1/32 =hardening depth on each side + 1/32 martinsite formation from each side totaling 1/8" thickness that is capable of being fully martinsitic.

My next question is this- Our discussion thus far has been based on what will happen to the steel given a sufficiently fast quench.

So how does the quench speed play into how the steel reacts to the quench.

What will form in the "martinsite capable" area of the steel given a quench that is not fast enough?

Will it then form a totally pearlitic blade ?

If this happens will the file bite the edge of the blade after hardening ?

How about passing the brass rod deflection test ? (IE- would pearlite readily fail this test)

I suppose my bottom line question is this- Is there any way for a maker to know with certainty that he has achieved the desired martinsite tranformation without actually having the steel analyzed with labratory equipment ?

Thanks for keeping this discussion technical fellas.

Thanks- Josh
 
Josh,

I had basicly the same thing happen on a W-1 blade a few years ago. It was full quenched edge down (horizontal as opposed to vertical). I had normallized it five or six times, trying to see how fine the grain would get. I also quenched an identical blade, except it was only normalised once, the same night. The single normalised blade fully hardened. The multiple normalised blade got hard to about 1/2" behind the edge all the way from ricasso to tip. After testing for edge holding ( performance was very close in both), I broke both to see what the broken surfaces looked like. The hardened portion of the differentially hardened blade was noticeably smoother than the fracture surfaces of the other blade, but not dramatically different. I read something around that time (by Kevin Cashen, I think) that said you could dramatically alter the hardening speed of simple carbon steels by dramatically decreasing the grain size through thermal cycles performed correctly for this purpose.

On a side note, I'm glad to see that this isn't devolving into a discussion about how you're somehow an inferior maker for using canola oil as a quenchant. Both of the above blades were quenched in a canola/vegatable oil mix, btw.

Is it "normalising" or "normallising" or maybe "normalizing"?:)
 
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Josh, you got it right on the depth of hardening thing. If a sharp file will not bite into the edge of the blade after quenching then you have formed martensite. If the steel cools too slowly the steel will be caught in the nose of the cooling curve in the TTT diagram and pearlite will form. If you get the temperature to fall below the nose of the curve before it converts to pearlite it will convert to martinsite unless you are doing something fancy such as austempering above the Ms point. For the simple steels that you mentioned you have less than one second to get the temperature from around 1400 degrees to under 1000 degrees to miss the nose of the curve. That is why some advocate for a harsher quenchant such as water or brine for those steels.

As far as whether or not you are using the "the correct" quenchant, nothing beats success. If it hardens, you are using the right quenchant. If not, you need to try something else.

Doug Lester
 
Thanks for the input guys !

Todd - If I understand you correctly your saying the larger the grain the faster the quench (your fully hardened blade).

Doug - Tha is what I thought. You either get under the nose, or don't. The steel doesn't know what it's being quenched in.

Again, not that I'm advocating canola just trying to figure out my HT with what I've got :)

Thanks again for the assistance. Josh
 
From what I've experienced and from what I've read, that's correct. Finer grained needs to have a faster quench. The fully hardened blade in the test above did have fairly fine grain, about the texture of velvet, I guess. The other one was more like the texture of my printer paper in the hardened area, really smooth. I'd like to repeat that test with brine quenching, but I can't find the time to test something just for curiosity's sake.:)
 
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Josh,

Maybe I read the thread too fast. I didn't see where you had listed the temperature of the canola oil. If is was either cool or hot, relative to "normal" quenchant temps (125-130 F) it would not drop the blade temp as fast as it could.

With any non-commercial quench oil, if it's old it will cool slower and more unevenly. Commercial quench oils have stabilizers in them to prevent cooling-curve change through use.

Scott McKenzie is Houghton International's metallurgist and quenchant specialist. He has said on BS and SF canola oil has the most appropriate cooling curve of the non-commercial oils and is quite fast... fast enough for 1095, I think. Canola oil is the base for Houghton's Bio-quench 700 (or maybe that's 600... I never remember which of the two is right) and it is extremely fast.

Well, there aren't any answers there, but maybe it narrows the question.

Mike
 
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