Really strange results heat treating 1095

T

Tom Lewis

Well-Known Member
I have never really worked with 1095 steel, but had some in my shop that I had bought years ago. Today I decided to use some. After the blade was ground to a rough shape. I normalized at 1600 degrees, then let cool, then normalized at 1500 and let cool.
Then I used my Paragon to heat to 1475 degrees, let it set five minutes, and quenched in room temperature Parks 50. While waiting for the kiln to cool down for tempering, I put the blade in a kitchen oven at 250 degrees. a few hours later when the Paragon had cooled down to 425 degrees, I put the blade in for two hours. When I took the blade out I checked with a file and it seemed soft. I used my Rockwell tester and it tested 40 RC.
I tried heat treating again used my Paragon at 1475 degrees, left the blade in five minutes, quenched in Parks 50. I then without any tempering checked the blade with the Rockwell tester and it tested 45RC.
I tried a third time. I set the Paragon at 1500 degrees, left the blade in five minutes, quenched in Parks 50 for about ten seconds, then finished quenching in water. Without any tempering, I checked the RC hardness and it was 55RC.
Now the really strange thing about this blade is, when I file the left side of the cutting edge which is maybe 3/16" thick, the file barely cuts. When I file the right side of the cutting edge the file skates off like a piece of glass.
I have checked my Rockwell tester against test pieces and it is accurate.
When the blade was in the Paragon oven at 1450 degrees I checked with a magnet and it was non-magnetic, so I think the Paragon must be pretty close anyway.
I don't remember where I bought the 1095 steel from. I always mark the steel with it's type when I get it so there will not be a mix up.
I don't think the RC tester has a problem, I don't think the Paragon oven has a problem. I am wondering if I really have 1095 steel.
I really don't understand why one side of the cutting edge is cut with a file while the other side maybe 3/16 away, is hard as glass.
Any thoughts would be appreciated.
 
This morning I checked the blade again and the file skated over both sides of the blade. I checked the RC hardness and it was 52RC. I check the ricasso where the steel is thicker. Maybe it didn't get as hard as the edge of the blade. I can't check the edge of the blade for RC because it is beveled.
 
Four areas to look at- heavily segregated 1095 (I have seen quite a bit of it), retained austenite (holding at 250F would do it, as would a 1500F soak, and Rc climbing over time is indicative of it), decarb (the file skating only in certain areas), insufficient solution (hold for at least 10 minutes at 1475F). These things can be difficult to troubleshoot long distance, there is often a small and overlooked variable that would be spotted in person but remains unknown in a conversation such as this. You will rarely, if ever, get a reliable Rc reading off a ricasso made of 1095, unless you are quenching in brine or something similar.
 
Interesting

Half of what is known about heat treating is (probably) wrong. Determining which half is wrong is problematic.
 
"You will rarely, if ever, get a reliable Rc reading off a ricasso made of 1095, unless you are quenching in brine or something similar." This is intriguing. Why is this so?
 
samuraistuart said:
"You will rarely, if ever, get a reliable Rc reading off a ricasso made of 1095, unless you are quenching in brine or something similar." This is intriguing. Why is this so?
Click to expand...

It has a lesser Mn content than the other 10XX series, resulting lower hardenability. Edges and thin sections can beat the curve. Thick sections, and a ricasso will often be the thickest, will allow for mixed pearlite formation, unless you have a quenchant fast enough to overcome the mass. Most oils do not fall into this category. I have managed to eliminate pearlite in cross sections as thick as a ricasso in a wedge or edge bevel shape with Parks #50. But a solid block of steel like the ricasso is a different story. If I have to do 1095 for somebody else, normally what I will go for instead are flat areas in the webbing between the rivet holes on a full tang piece, otherwise I hate trying to get accurate HRC on 1095.
 
Perhaps a silly question, but are you getting the steel into the quench "under the nose"?

I.E., you're not taking too long to quench the blade once it's out of the oven are you?
 
That's a very good question. My quench tank is right behind the Paragon oven. I pull the blade out of the oven, turn around and immediately dunk it in the Parks 50. I don't think it could be done any quicker.
Thanks for the question, I appreciate you thinking about the experience I had.
I plan to heat treat another 1095 blade today. I hope it goes better.
 
Remember that the nose is somewhere around 1000-1200° and if you are heating it to 1475° it gives you a few seconds to get the blade into the quenchant. That one second that everyone seems to talk about with this steel is at the nose.

Doug
 
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