1095 success?

Garrett Schmidt

Garrett Schmidt

Joined
May 17, 2006
Messages
450
Ken and I decided to give a brine quench a try since my last attempt at heat treating 1095 was a mess. We tried to be as "scientific" as possible as to leave as many unexplained variables out as possible. Blade was 3/16" x 1.5" x 9" hollow ground. The first thing we did was to get the brine ready. We filled a metal bucket with water and mixed in some water softener salt. We heated that over a burner until the salt was disolved and the water was at approx. 150 degrees. The amount of salt at this point was around 70% according to a salinometer(i think that's what it is called...a little bobber type device that floats at different levels according to how salt saturated the water is) When the brine was just about ready we heated the blade to 1475 in a controlled oven and let it soak for about 5 minutes. At this point I was almost expecting a severe crack or ping to occur and had resigned myself to that idea since it was our first attempt and the 1095 horror stories are so abundent. Ken took the blade out of the oven and plunged it into the brine tip down until the whole thing was submerged. For those of you who have never done this, it is a site to see for sure. The reaction with brine is totally different from oil. The water boils instantly and it makes this bubbly gurgling sound and then about 4 seconds later it is over and goes back to a steaming bucket full of brine. At this point the blade had cooled a lot and the water had warmed some so we let it sit for a minute until it cooled enough to handle. Right away we knew that at least the blade didn't explode or crack. It did warp but only a small amount. The file skated over the edge along the whole cutting edge so that part was good. The weird thing is that the spine and about 80% of the blade behind the edge was soft. You can literally scribe most of the blade with a carbide point right up to about the last 1/4" from the edge. You can almost even see a hamon line which was totally unplanned.

At this point I am wondering a couple of things:
1. Maybe the brine was too hot when the blade went in.
2. Did the spine and the rest of the soft area undergo any transformation at all, even though it didn't harden completely?

Even though the results were unexpected (hamon goodness:)), I would still consider this a success of sorts. What are your thoughts? Any ideas on why the blade didn't harden completely? Anyone think I am crazy to be trying 1095 when I know I can get near perfect ATS-34 results through Ken's heat treat methods...lol?
 
+1 AWESOME :thumbup: I just quenched W1 the other day in 10-20% brine and came out with 4 major cracks along the edge and the rest looked like cracked glass my edge thickness was a little to shallow at about .030" should have been .060-.070" It was my first cracked blade in brine. oh well stuff happens. To answer your questions 150ºF is a lil to high, I'd back it down to 110 -120ºF. That could explain the soft back. I think a good maker should offer both a good carbon and a good stainless steel choice for his blade styles. BTW did you coat it with anything to avoid decarb or is his oven a nuetral atmosphere? the reason I ask is the coating could have acted like a clay and caused the hamon.

Jason
 
The most effective concentration for brine is about 9 % NaCl !! It is more effective at room temperature though safer if you warm it up !! The salt acts to break up the vapou barrier thus speeding the cooling rate !!
 
You heat oil to reduce its viscosity, making it faster. Heating water is counterintuitive to me. I guess, being closer to its boiling point you reduce its quenching effectiveness and lower the shock? That is possibly why the spine failed to harden?

I wonder how it would work if you tried again with cooler water?

BTW, an edge with pearlite in it will still skate a file. RA too.

From my understanding of it, a good soak on the low end of the austenitizing range improves your luck using brine. That is exactly what you did - so it sounds to me like you're on the right track.

just my .02. I haven't water quenched anything in years, and that stuff wasn't knife stuff.
 
Nathan the Machinist said:
You heat oil to reduce its viscosity, making it faster. Heating water is counterintuitive to me. I guess, being closer to its boiling point you reduce its quenching effectiveness and lower the shock? That is possibly why the spine failed to harden?

I wonder how it would work if you tried again with cooler water?

BTW, an edge with pearlite in it will still skate a file. RA too.

From my understanding of it, a good soak on the low end of the austenitizing range improves your luck using brine. That is exactly what you did - so it sounds to me like you're on the right track.

just my .02. I haven't water quenched anything in years, and that stuff wasn't knife stuff.
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I thought about the pearlite or retained austenite too. Is there any way to tell? The one hint that I thought about was the hamon. There is a definite difference between the two hardnesses in color and the way it reacted to etchant. I suppose this doesn't prove that the edge is martensite but at least there are two different things there. Possibly pearlite flats/spine and a mix of martensite and RA on the edge? Or maybe something to that effect? Is there any real way to tell if you have full martensite transformation?...without using a microscope I mean If there is retained austenite, would cryo help in fixing that? Bare with me, I am still trying to learn about this stuff and sometimes it seems that my jarhead brain just doesn't respond well to this learning thing:)
 
X-ray crystallography I think is the only way to tell as far as a non-destructive test to tell the percentages of martensite, pearlite [the ferrite] and retained austenite.
 
I wondered about the heat factor in brine quenching too. I looked couple of knife makers sites and one stated that brine should be heated to 170 degrees or more for quenching. Another stated that theoretically if you were to quench in boiling water/brine the blade would come out softer than an oil quench.

I've done a couple of 1/8 in thick 1084 blades in 7% brine that was heated to 180 degrees more as an experiment than anything else and they came out with no cracks or warpage. I know it's not a scientific test but the file skated off of every part of the blade. I broke the blade and the grain structure seemed fine and uniform.

My guess is that heating it does reduce the shock factor as Nathan said. Some oils are heated to 140-150 degrees for quenching to speed their cooling rate. Brine and water work in reverse as I understand it. Heating them slows the the rate.

From reading your post I was a little confused. Did you take it out after 4 secs. and then put it back in? I wonder if that had anything to do with the soft back.

Joe
 
Garrett Schmidt said:
I thought about the pearlite or retained austenite too. Is there any way to tell? The one hint that I thought about was the hamon. There is a definite difference between the two hardnesses in color and the way it reacted to etchant. I suppose this doesn't prove that the edge is martensite but at least there are two different things there. Possibly pearlite flats/spine and a mix of martensite and RA on the edge? Or maybe something to that effect? Is there any real way to tell if you have full martensite transformation?...without using a microscope I mean If there is retained austenite, would cryo help in fixing that? Bare with me, I am still trying to learn about this stuff and sometimes it seems that my jarhead brain just doesn't respond well to this learning thing:)
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If there is RA, yes, cryo would probably help. But I doubt you'll have a problem with RA with 1095 soaked on the low side. I was only mentioning it as an example of something that could be there and still skate a file.

Now, pearlite is a different story. From my understanding, it can reach well past a hamon line. I simply don't know. The fact that much of the blade didn't harden up to 1/4" of the edge would make me nervous. 1095 is really bad about pearlite. I would think a water quench would do the trick, but I would also expect it to more fully harden.
 
Here's something to add to the confusion :D. The title of this book is "Tool Steel Simplified" , by Frank R. Palmer and George V. Luerssen, published by the Carpenter Steel Co. This printing is July 1968. I hope the attachments are readable.



Saltbrine.jpg

Saltbrine001.jpg
 
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Why does that add confusion ? The only thing missing in that is a discussion of agitation which you makers should ALWAYS do !!
 
But mete you would be astonished at the number of makers who do not. Another old bladesmithing myth that refuses to die is that agitation causes distortion (yes, improper agitation does), this is another one of those points that will often get us techno-jerks the standard answer "why over think things, I've been doing it this way for years and it works fine":rolleyes:(I wished I had the head bang emoticon here). Not everybody can set up water jets or J-tubes, but anybody can keep the blade moving in the quench. Water based quenchants may not matter as much since I am not sure if we can move the blade enough to evenly kill that vapor jacket, but oil is not only a breeze it is vital.
 
It did warp but only a small amount. The file skated over the edge along the whole cutting edge so that part was good. The weird thing is that the spine and about 80% of the blade behind the edge was soft. You can literally scribe most of the blade with a carbide point right up to about the last 1/4" from the edge. You can almost even see a hamon line which was totally unplanned.
Click to expand...

That is exactly what happened the first time I quenched 1095 but I was using a sodium hydroxide solution and just dipped it in and pulled it out as fast as I could. I should have left it as it was because I ended up cracking it and the next two blades.
 
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I need to correct something from earlier. The reading on the salinometer was 70....not 70%. According to Keith's post of the book, that is about 28%. I guess the two variables that I would imagine would've caused it to not harden the most would be the salt content and the brine temp. I guess I can be edgeikated aphter all. Thanks for the replies all.
 
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