1095 hardening question

PetrifiedWood

Well-Known Member
This might seem a bit off the wall but...

I want to make some flint and steel strikers from 1095. I have them already cut out (got them laser cut).

When they came form the laser company, they were hardened about 1/16" in from the edges from the laser, enough to strike sparks. But, I want them through-hardened because I'm going to be putting a sharp edge on them for striking ferrocerium rods as well as flint.

I've made about 27 of these strikers using 5/32" thick O1 steel. I use an evenheat kiln and ramp up to 1275 and hold for 15 minutes, then ramp up to 1500 and soak for 15 minutes, then quench into room temp mineral oil. This has worked fine for the O1 strikers. They get hard enough to strike nice sparks, and they are at least RC60 as verified with my hardness testing files.

I tried the exact same program using the 1095 strikers (these were 3/16" thick, so only slightly thicker), and they got softer, rather than harder. They don't throw sparks at all, and if you put an edge on them they roll easily. I haven't checked their hardness with the files but something obviously went wrong.

Time from the kiln to the quenchant was less than 2 seconds, and I agitated them vigorously (not concerned about warping because they don't need to be precise).

What confuses me is that Evenheat's program for 1095 is the same as that for O1. But I had drastically different results with my program.

So do you think my problem is with the heat program, or the quenching? Should I try water quenching them instead of oil? Was 12 minutes at 1500 too much for the 1095? Did I burn out all the carbon?

A friend of mine suggested throwing them in a pile of lit charcoal and letting them cool overnight in hopes that some of the carbon would be replaced if decarb was the problem.
 
The 1095 is a different beast from O1 and austinizing it and getting the carbon to disolve is only part of the equasion . Also not all 1095 is created equal. If it is low manganese, it may not want to through harden for you because it is very shallow hardening. It will only harden to twice the depth of hardening in things with thin cross sections and that will depend not only on the manganese level but also the grain size. Thicker than that and the steel will only form pearlite. The finer the grain the shallower the hardening. What you could be seeing is that the only parts thin enough to harden are found at the corners of the edges. Another problem could be that the oil is cooling the steel too slowly and is allowing pearlite and/or bainite to form. You may need to go to something more agressive like water or even brine.

Your soak should be fine. None of the IT diagrams that I have for give upper critacal temperatures of hypereutectic steels such as 1095 but I think that you are good there. Don't worry about carbon burn out at those temperatures. That's really not much of a problem until you get up to welding temperatures. Your friends suggestion to throw them into hot charcoal and let them cool slowly would only compound your problem by making them even softer.

Doug
 
The 1095 is a different beast from O1 and austinizing it and getting the carbon to disolve is only part of the equasion . Also not all 1095 is created equal. If it is low manganese, it may not want to through harden for you because it is very shallow hardening. It will only harden to twice the depth of hardening in things with thin cross sections and that will depend not only on the manganese level but also the grain size. Thicker than that and the steel will only form pearlite. The finer the grain the shallower the hardening. What you could be seeing is that the only parts thin enough to harden are found at the corners of the edges. Another problem could be that the oil is cooling the steel too slowly and is allowing pearlite and/or bainite to form. You may need to go to something more agressive like water or even brine.

Your soak should be fine. None of the IT diagrams that I have for give upper critacal temperatures of hypereutectic steels such as 1095 but I think that you are good there. Don't worry about carbon burn out at those temperatures. That's really not much of a problem until you get up to welding temperatures. Your friends suggestion to throw them into hot charcoal and let them cool slowly would only compound your problem by making them even softer.

Doug

Thanks Doug. So my problem then is more likely to be the quench? I'll give water a shot tomorrow and see if that does the trick. I'm not sure about the manganese content as this steel is "1095" from a friend's friend. I am confident that it is actually 1095, but I don't think he'd be able to find out the specific composition for me.

It did harden around the edges where it was laser cut (presumably in the air). So it still seems a bit mysterious to me that oil which should be faster than air can't even make it hard on the corners of the edges. I have a 70 degree (inclusive) chisel grind on the back side for scraping ferro rods. After quenching, I touched up this edge (exactly as I have done with O1) on a 120 grit belt, keeping it cool with frequent water dunks and the edge rolls when trying to strike a rod. Ferrocerium is very soft.

I thought since it was a chisel grind that I might have some soft decarb on the flat side of the edge so I ground off all the scale and tried again and it still rolled the edge. I'm truly at a loss.
 
Hmmm..... 1095 from a friend's friend?

I'd be a little suspicious myself. Can you ask this friend's friend where he got it from?

At any rate, when I heat treat 1095, I just set my oven to 1475, give it a 5 to 10 minute soak, and take directly to the quench (Parks 50). I'd then probably temper it at 300 to 325 or so if I were making strikers.

If you're using something like vegatable/canola oil, make sure it's heated to about 130F, or you won't cool fast enough. I'd try using fresh oil too. Another option would be brine (salt water), though you might crack a few in the process.

Remember, 1095 requires a fast speed quench, where as O1 is more of a medium speed.
 
When making strikers, I use brine at 110° to maybe 120°. It is less violent than water, and less likely to crack the 1095. In my experience. With one type I make, I cannot afford failures. Too much time in them

pennyknife736_640x480.jpg
 
I'm a little at a loss to explain why you evidently have some air quenching from the laser cutting but have problems getting to harden in oil reguardless of what the steel is. You may have to face that the steel will never harden all the way through with fine grain but you should ge able to get it to harden on a thin edge. I hate to advise it but another thing that you can try is to soak it at around 1700-1800 degrees to deliberately increase the grain size and thus increase the depth of hardening.

As far as steel that was gotten from a friend of a friend I hope that that person absolutely knows that he got 1095 or what you're dealing with is mystery metal.

Doug

Corresponding with Kevin on this is a great idea. It's unfortunate that he's had problems with personal attacks on these boards and no longer participates in board discussions but I have found him to be knowledgable and helpful.
 
Petrifiedwood, if you feel I may be able to help out with any of your 1095 questions, you can also feel free to e-mail me at kevin@cashenblades.com

Thank you Kevin!

If my next try doesn't work I might take you up on that.

Andrew,

I think what I'm going to do is have a bucket of water standing by, and try heating my oil to 130 or so and try one striker in each quenchant.


LRB,

That's a beautiful tinder pouch!

For anyone who's curious, here is a picture of the strikers I've been making. (This one is O1.)

IMG_1283.jpg



The back edge has the grind on it for striking ferro rods, and the front edge is for striking sparks from flint.
 
Ok, just wanted to give you guys an update.

I got one hard enough to spark using my regular O1 heat program, and quenching it in cold water. There was a huge difference in the time it took to stop "fizzing" in the water vs. the oil. It probably cut 2/3 off the time at least. It went from 1475 degrees to room temp in a matter of about 8 seconds or so. I could tell right away on the grinder as I was touching up the edge that it got hard as it was producing a lot more sparks from the belt.

I did have to put a slight back bevel on the grind to keep the edge from rolling because of a very slight soft layer on the surface (maybe 2-4 thousandths or so). But it is now sparking well with flint and hard enough to work with ferro rods too.

My test files show a hardness somewhere between RC60 and RC65, probably toward the harder end of the two. this is harder than I've been able to achieve with O1. I'm impressed with the water quench! I had intended to try one in warm oil but I tried the water first and it quenched so fast I decided to stick with water for these.

So do you guys recommend tempering for a couple hours at 325 or so, or just leaving them as is. I'd hate to draw them back to where they don't spark as good.
 
I would temper them just a little to relieve stress in the steel. A temperature of 325 degrees will do little in the way of softening the steel but it may relieve some of the stress from quenching. You don't want any of them to snap from normal use or from just sitting around. I would do that at least twice to try to trigger retained austinite to convert to martensite and then temper that. Three times wouldn't hurt anything even if it didn't do any good.

It sound like the water is cooling things fast enough to miss the nose of the IT curve so you don't pick up a bunch of pearlite formation.

Doug
 
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