Proper heat Treat on 1095 or Just voodoo

curtisk

curtisk

Well-Known Member
Ok, there seems to be a vast array of suggestions/opinion on heat treating 1095. The chart shows 1475F as the optimum temp, but 1095 does not become non-magnetic until around 1560. If going by the chart it does not seem that the maker will make full use of the available carbon. Should one go non-magnetic or stick with the chart, or just do a little chant and wave a dead chicken around?

Curtis
 
Where do you see that 1095 becomes non-magnetic @ 1560?

At any rate, I think you'd be best to stick with the 1475F on the chart. Go much higher than that, and I believe you risk grain enlargment.

As far as the dead chicken: coat with melted butter, season to taste, and place in tempering oven at 400F for 1 hour. Carve with previously crafted knife, and enjoy!
 
Also, this question would probably be much better and more thoroughly answered in the Heat Treating forum.
 
If you are getting that austinizing temperature from the appearance of the steel when it becomes non-magnetic be advised that estimating temperature from steel color can be very inaccurate. It is highly influenced by ambient light. I'm even starting to think that I don't see red in hot steel. Everything looks to me to be organge until it turns yellow. I'm going to get some temperature sticks from the local welding supply house before I heat treat my next batch of blades. FYI, the ITT diagram that I have for 1095 gives the Ae1 (lower critical) point at approx 1340 degrees and a carbon phase diagram gives the Accm (upper critical point with the temperature increasing) at a little over 1500 degrees and you want to stay between those two temperatures when heating to quench. Don't confuse that with the actual temperature that the steel was austinized at to collect the data which can be above the upper critical point.

Doug
 
I'm sitting here, trying to figure out how to say this without sounding like a butt head, and not sure how to, so I'll just say it.

A few years ago they messed around with the chemistry of 1095.....essentially the widened the specs on some of the element contents, with the whole idea being to lessen the production costs. For the majority of 1095 users the changes didn't make any difference(s). But! After receiving a large number of phone calls and emails from folks who could not get their 1095 blades to harden, I started digging around and found that because of the changes (mainly manganese content variance from batch to batch, and even from bar to bar within the same batch) sometimes the steel would harden fine, and other times the TT curve was less than 1 second! (that means that in order to harden, the steel has to go from the critical temp, to 400 or less in LESS THAN 1 SECOND......Not Happening!) For the average Bladesmith/Knifemaker, that is physically impossible. Because of that, I no longer use, nor recommend 1095. My thought pattern is that I don't have the time to waste all the effort in getting a blade to the heat treating phase, only to be gambling as to whether I can harden it or not.

Now, here's the kicker.....many folks will ask the question.... Why didn't they tell us about this? When I spoke with a few people in the industry, who I consider friends, I got responses such as "The changes are irrelevant to most who use it" (1095), "Knifemakers are such a small percentage of steel buyers, we honestly don't care what they think." Those are not made up, those are statements made to me when I was researching the issue of non-hardening 1095.

So, my conclusion is this.....the decision to use 1095 is up to each individual. I simply do not have the time to waste on something that I might or might not be able to harden, therefore it no longer has any place in my shop.
 
Last edited:
If you are getting that austinizing temperature from the appearance of the steel when it becomes non-magnetic be advised that estimating temperature from steel color can be very inaccurate. It is highly influenced by ambient light. (QUOTE )

You are correct about ambient light . The Japanese call it Yakire . Basically you are doing is ht and quenching at dusk or early in the morning . If you try it in full light , it just doesn't work . When done correctly it is very accurate . So much that I can get about 100F difference between blade edge and spine . It produces what some smiths call a double hamon or "Utsuri" can only be produced in the narrow range between 1450-1550 . with 100F difference in actual temperature.
The japanese have been doing this for 1000 years
 
Last edited:
Thanks for all the input gents. Andrew, I actually ran some magnet tests with 1095 and it is still “grabby” at 1550F. It only stops adhering to a magnet when you get over that temperature. As for the “dead chicken”, that would be a much better use for it than my idea of just waving it around. I guess the chant is still applicable though.:3:
Doug, as I mentioned in my response to Andrew, I have tested the stuff repeatedly and it is consistent; 1095 will not stop adhering to a magnet until you reach 1550 (I run a PID w/type-k thermocouple). I made a couple of knives from it and there did not appear to be any grain growth. I also did a test piece and when snapped, the appearance was good ole grey felt. Go figure.
Ed, you have to be kidding, “…we honestly don’t care what they think.” Sounds like there are a few steel manufactures who are in need of an extended baptism (when the bubbles quit comin’ up, you know it took). :biggrin: Honestly, some folks are just plain rude. I can see why you don’t have any 1095 in your shop sir.
Bubba-san, I have never heard of the “double hamon”. Interesting. Question: based on your experience, do you think there is too much grain growth when you get above the 1475F mark in 1095?
Thanks again guys. I really really appreciate the input.
Curtis
 
Ok, just because the pyrometer says that the forge is up to 1550 degrees it does not mean that the steel is up to 1550 degrees. Now if you are talking a molten salt bath then that's a different story. The transfer of heat from liquid to solid is much more effecient than gas to solid. You can put a pot of water in an oven at 250 degees and it won't boil. The transfer of heat is too slow. Another way to test this would be to get some temperature sticks and apply them to the steel and see when they melt. Sticks in 1450, 1500, and 1550 should do if you want to do the experiment.

To expand on what Ed said. For most smelters making an alloy to the specifications of only a minority of customers is not financially practicle. Stating "we don't care what they think" is a little blunt but it is real. A way around it is for a customer to make a large enough order to make it worth while for the smelter to make a special alloy. That's what Aldo Bruno did for the 1095 he ordered. It has enough maganese in it to drive to nose of the ITT curve far enough to the right for the actual cooling curve to miss.

Doug
 
Ed...Thanks for posting that bro...Kevin steered me towards 1084 due to the involved HT and now I am even more glad I stopped playing around with it and went with the 1084fg from Aldo...

Bubba...I thought the different or Utsuri was due to different thickness of clay on the blade? so its the heat transfer itself?
 
Doug Lester said:
Ok, just because the pyrometer says that the forge is up to 1550 degrees it does not mean that the steel is up to 1550 degrees.
Click to expand...

That would be my suspicion... I have a quality PID and a K type TC as well, and when I have held a magnet to my 1095 @ 1475-1500F I don't feel it grabbing. Granted, I'm using a homade oven that's very well sealed and not excessive on volume, with a centrally located TC. The oven also holds very stable at +/- 1 or 2 degrees.

I'm not sure what your oven looks like or how it's set up, but I would try the heat sticks or another calibrated TC. In fact, I should probably double check mine too.
 
You must log in or register to reply here.
Back
Top