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I recently had a weirdness appear in a 1095 blade that I can only describe as "clouds". They started to appear around 400 grit and will not go away.

I even went back to 320 and they just keep developing.

So my hive-brothers, anyone ever have this happen?

 

Clouds 2 V2.jpg

 

Cloudy steel V2.jpg

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No, I did not clay the blade.

It is about .200" (5,3 mm) at the thickest part of the spine, and wasn't much thicker in the quench.

Fast oil, quenching at 1485*F. tempered at 450/475*F

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Looks like auto hamon to me!  That shows you normalized very well indeed.  And got the quench just right. B)

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I was thinking the same thing as Alan.  I"ve never had one turn out that wispy before though! 

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It's a tough life when the advice givers needs advice :D

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5 hours ago, Gerhard Gerber said:

It's a tough life when the advice givers needs advice :D

 

The last time I thought I knew something completely I was 18.  The older I get the less I'm sure I know! :wacko:  I just know how to sound like I know what I'm talking about. ;)

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7 hours ago, Alan Longmire said:

That shows you normalized very well indeed. 

 

OK, I can't get this statement out of my head.  I take it that grain size impacts the activity or existance of the hamone?

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The way that works is (keeping in mind what I said about sounding like I know what I'm talking about) that grain size is directly related to hardenability and depth of hardening in a simple shallow-hardening steel like 1095.  The smaller the grain, the more shallow the hardening, and thus the thinner the depth of hardening.  As I understand it, when you get that kind of auto-hamon in an oil quench, you are teetering on the precipice of having to go backward in time to beat the nose of the TTT curve and achieve hardening.  You know, that thing where you have less than one second to get 1095 from above 1425 degrees F to below around 1000 degrees F?  That's assuming a grain size of 9 or 10 (units don't matter, the larger the number the smaller the grain).  Say you refine the grain to 13 or 14 (industry stops at 10), you have now moved the nose of the curve closer to the Time = 0 axis of the graph.  

We had this happen at my February guild meeting. A new guy had a 1095 blade about 3/16" thick, not bevelled, that he wanted to harden.  He had done numerous normalizing cycles, like eight or ten.  I fired up the club gasser and guided him to decalescence, whereupon he quenched in fresh warm canola. No effect.  Didn't work the second time either.  We were thinking about going to water, but the only water we had was ice cold and that seemed like a bad idea, which is when I realized that we'd probably refined to grain to the point that it was physically impossible to harden it with the setup we had.  The solution?  Take it back up to critical, go a little hotter, hold for one minute to grow the grain a bit. Quench. And bam, it hardened perfectly.  Once he gets it ground it will probably have a bit of auto-hamon in the center of the blade.  

I know about this because I know another guy who cycles 52100 so much that it has to have a water quench or it won't harden.  And that's supposed to be impossible... ;)

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Huh. Kevin Cashen told me it's just decarb. Go figure. 

I'm used to getting all the scientific gobbledygook from Kevin and he pastes me with a simple answer. Alan on the other hand......I like this answer much better!

 

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I always defer to Kevin, but in this one case I like my answer better too!^_^

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How much steel was removed after HT? Did you use anti-scale? It may give us a hint whether it's decarb or hamon. For now, I'm on the hamon side as well.

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On 3/13/2020 at 5:56 AM, Alan Longmire said:

I always defer to Kevin, but in this one case I like my answer better too!^_^

Just for the record, I told Kevin about your theory and he said "Yes that is very possible. Finer grain = faster quench requirements in simple steels."

So, I think it's fair to say that Kevin likes your answer too!

 

On 3/13/2020 at 7:57 AM, Joël Mercier said:

How much steel was removed after HT? Did you use anti-scale? It may give us a hint whether it's decarb or hamon. For now, I'm on the hamon side as well.

There was a fir bit of grinding post HT and yes I used my latex based, white, anti scale secret formula. The clouds only started to show up at 400 Grit hand finishing and they haven't disappeared even when I go back to 320. I'm taking it back to the grinder to see if I can grind through it. If yes, it's decarb. If no, it auto-hamon.

My money is on the latter.

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Posted (edited)

Joshua,

 

I believe that you're seeing pearlite or retained austenite.  1095 is always a tricky quench and it's hard to get a high % of martensite.  You didn't say what your quench oil was.    Also you didn't say at what temperature you had the quench oil.  All can play a part in this.

 

I don't believe that it's an auto hamon as they're usually more linear than this.  I believe that it's probably an incomplete austenitic conversion. Just my $.02.

Edited by Gary Mulkey
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Gary,

Thanks for chiming in. Your observations are always welcome and appreciated.

I have been using the same fast quench Texaco something oil and process for years. Preheated oil to 120*F-130*F. I quench my 1095 at 1480*F and achieve a as-quenched hardness (tested with chisels) of 64+ HRC.

 

Here is my anti-scale application and a post-quench photo of other 1095 blades.

anti-scale.jpg

 

post quench blades.jpg

 

 

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I had the exact same thing happen to the last knife I made out of 80CrV2. Was driving me nuts trying to get a nice shine to it. After god knows how many sheets of sand paper I finally just gave up and put a handle on it. Glad to know it (most likely) wasn't my sanding technique. 

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Was the blade forged or done by stock removal? And where is the steel coming from? 

 

I'm asking because the steel from a certain place which buys all it's steel from the same mill in Europe have some serious grain structure issues(too coarsely spheroidized) and must be HT'ed using a special schedule to dissolve the carbides. Only when done by stock removal of course...

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11 hours ago, Joël Mercier said:

Was the blade forged or done by stock removal? And where is the steel coming from? 

 

I'm asking because the steel from a certain place which buys all it's steel from the same mill in Europe have some serious grain structure issues(too coarsely spheroidized) and must be HT'ed using a special schedule to dissolve the carbides. Only when done by stock removal of course...

The source of this steel was Alpha Knife Supply and it was forged. It was the blade I posted about that developed a warp during the tempering ( pretty sure you commented on that post ). 

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