1095 Won't Harden?!?

milkbaby said:
New kiln? Don't forget to try hardening a known good steel sample in it to make sure that's not your problem!
Click to expand...
This may be a overly simple thought but the curie point of 1095 is 1414 F, so set your kiln to 1400 and the blade should still be magnetic, bump it up to 1425 and it should be non magnetic, that tells you it’s within 10 degrees or less. You could probably safely assume it’s accurate on simple steels are that point. Correct me if I’m wrong.
 
Joshua Fisher said:
This may be a overly simple thought but the curie point of 1095 is 1414 F, so set your kiln to 1400 and the blade should still be magnetic, bump it up to 1425 and it should be non magnetic, that tells you it’s within 10 degrees or less. You could probably safely assume it’s accurate on simple steels are that point. Correct me if I’m wrong.
Click to expand...
Ac1 is reached at around 1370’f which would be nonmagnetic. I think curie point is used for pure iron.

Hoss
 
Last edited:
Joshua Fisher said:
This may be a overly simple thought but the curie point of 1095 is 1414 F, so set your kiln to 1400 and the blade should still be magnetic, bump it up to 1425 and it should be non magnetic, that tells you it’s within 10 degrees or less. You could probably safely assume it’s accurate on simple steels are that point. Correct me if I’m wrong.
Click to expand...
I have found the magnetic trick kinda problematic. The issue is it’s not like a light switch. It seams to be a gradual reduction in Magnetism. So when you start getting close it’s hard to tell exactly where the cut off point is. I would doubt even a heat treat oven is accurate to within 10° unless it’s been calibrated with a dry well block.
 
DevinT said:
Ac1 is reached at around 1370’f which would be nonmagnetic. I think curie point is used for pure iron.

Hoss
Click to expand...
Thank you for the correction, and I read through Larins article and it’s very interesting learning the science be hind the process, it can still be used as a good benchmark in my opinion, especially if the kiln or temps are in question.
 
Joshua Fisher said:
Thank you for the correction, and I read through Larins article and it’s very interesting learning the science be hind the process, it can still be used as a good benchmark in my opinion, especially if the kiln or temps are in question.
Click to expand...
It can’t be used if your assumption is that 1095 will become no magnetic at 1420. It won’t. It will be at a substantially lower temperature.
 
Larrin said:
It can’t be used if your assumption is that 1095 will become no magnetic at 1420. It won’t. It will be at a substantially lower temperature.
Click to expand...
I’m sorry Larrin, I should have been more specific, I meant that the lower temperature when it becomes non magnetic can still be used as a benchmark. I knew different steels had different points they became non magnetic but didn’t know the exact science behind it, and I truly appreciate your articles that help shine some light on the detailed specifics. I’d be interested to know if the OP has ground a bit of steel away on the edge and checked if his blade is indeed hardened. It wouldn’t surprise me if he has a bit of decarb and at this point has repeated the heat treat multiple times which doesn’t necessarily help matters.
 
Stacy E. Apelt - Bladesmith said:
Yes, Parks #50 is a room temp oil. the normal range is 60-90°F. A bit cooler or hotter won't matter, but 120 is too warm. However, your blade should have hardened.

What volume of oil are you using? For a large 1095 blade it should be several gallons.
Are you sure it isn't hardened?
How have you determined it isn't hard?
Have you ground into the edge to see if there is hard steel under a layer of decarb?
Click to expand...
2 gallons. The chefs knife is probably 12" overall but I decided to try another one that was smaller, it's 3/16 and 9" long, just a basic camp knife made out of an older piece of 1095 that I have successfully hardened before and I still had the same issue. I decided to heat treat again and quench in water to see what would happen and it still did not harden. I took a 45 hardness file and cut a groove in the edge of the blade with only 3 passes... Through process of elimination it seems that its pointing to the normalizing treatment I did may have something to do with it.
 
JTknives said:
Do not be surprised if the steel is bad as it’s not uncommon to get carbon steel from NJSB that won’t harden. I have not seen it in their 1095 as I don’t know if we have ever gotten any blades in that from customers. Our most common issue is their 1084 and W2. I have had great results with their 80CrV2 and it’s fantastic steel. We run our parks 50 at 100° for all our quenching. When it’s at that temp it seams to preform better and the quench scale comes right off in the quench. At lower temps the blades would hold into that dark black crusty scale.
Click to expand...
Thanks for the reply, I called them and they did inform me that they make a new 1095 now that is 85% annealed and to not normalize it because it could introduce carbides into it. I tried it on an older piece that I had from stock that I have successfully hardened before and had the same issue. I tried it again and quenched it in water to see what would happen and still didn't harden. It seems the normalizing treatment may be the issue. I am going to try a scrap piece of steel and see if that hardens...
 
Joshua Fisher said:
Just jumping in here, I have a knife I heat treated from Njsb’s 1095 from an old batch and several from their newest batch and have had no issue hardening any of it, the one from the old batch I actually did some testing on it today chopping through 1/8” brass rod and chopping as hard as I could with a small knife on a piece of antler probably 20-30 times with no edge damage other than the very slightest glinting on the brass rod chops that was fixed with 10 passes on each side on a 1000 grit water stone the exact knife I tested today was heat treated in a forge doing 3 thermal cycles at reducing temps, one at around 1600-1650 the second at critical temp so between 1450-1500 then the last at sub critical to help relieve stress. Brought back up to critical then quenched into room temp parks 50. I heat treat the stock at full thickness to be able to easily straighten if needed and reduce warping on the edge. Working with 3/32-1/8” stock this works really well for me. Are you checking for hardness right after the quench or after temper? If you are using a good sharp file it could skate before tempering and bite in slightly after tempering. I like to use a round file to check if it’s hardened or not, I just feel like it gives me the most accurate feedback. Also if you are soaking the steel too hot you could get some decarb, try grinding your edge in a little bit then check again and see if it’s still not hardened.
Click to expand...
Thanks for the reply,
I called them and they did inform me that they make a new 1095 now that is 85% annealed and to not normalize it because it could introduce carbides into it. I tried it on an older piece that I had from stock that I have successfully hardened before and had the same issue. I tried it again and quenched it in water to see what would happen and still didn't harden. It seems the normalizing treatment may be the issue. I am going to try a scrap piece of steel and see if that hardens... The normalizing treatment was one Nick Wheeler suggested for 1095 which is 1600,1550,1500,1450, and 1400x3. Then ht at 1475 with a 10 min soak. I check the hardness before temper with round hardness files. I was able to file a groove into the edge in 3 passes with a 45 hardness file...
 
Thank you guys for the replies, still no success yet but it seems it may be in my normalizing cycle that is causing my issue. The normalizing treatment was one Nick Wheeler suggested for 1095 which is 1600,1550,1500,1450, and 1400x3. Then ht at 1475 with a 10 min soak. I have tried quenching in room temp parks 50 and also heated at 100 and 120. I also tried water to see what would happen and still nothing... I am going to try to harden just a scrap piece tomorrow that has had nothing done to it and see what happens. Process of elimination right? If it is the normalizing do you think there is anyway to save these blades? I have treated each one 3 times with different temps for the quench and up to 1500 for the ht on one of them. You guys rock
 
If you are water quenching 1095 and it won't harden, something is off with the HT oven. Heat the blade that didn't harden in the forge until it is just a tad above non-magnetic and quench it. If that hardens, then I suspect the HT oven has an issue with the TC or the controller.
 
Conor Jensen said:
Thank you guys for the replies, still no success yet but it seems it may be in my normalizing cycle that is causing my issue. The normalizing treatment was one Nick Wheeler suggested for 1095 which is 1600,1550,1500,1450, and 1400x3. Then ht at 1475 with a 10 min soak. I have tried quenching in room temp parks 50 and also heated at 100 and 120. I also tried water to see what would happen and still nothing... I am going to try to harden just a scrap piece tomorrow that has had nothing done to it and see what happens. Process of elimination right? If it is the normalizing do you think there is anyway to save these blades? I have treated each one 3 times with different temps for the quench and up to 1500 for the ht on one of them. You guys rock
Click to expand...
Not sure if this would help but perhaps heat the blades up to 1600-1700 then place them in vermiculite over night to try to anneal them then start over. It seems odd to me that they would suggest normalizing cycles to be the issue but it also seems like maybe you are doing too many cycles, in my experience 3 cycles of descending heat seems to work just fine but perhaps someone else can jump in. Another thought is perhaps do a high temp cycle as if you were forging the steel, so 1800-1900 without a soak time then start descending cycles from there, if you have more steel from the same bar perhaps cut off 4–5 coupons and create a baseline of what works and what doesn’t. As far as not being 1095 try spark testing it, if it sparks good then it gives you an idea it’s high carbon steel then try dipping a section in water, if it rusts Very rapidly then it’s not stainless. Just about any high carbon steel quenched in water from 1500-1600 degrees should harden. It doesn’t mean that’s the ideal heat treat for the steel or what type of high carbon steel it is but atleast you know it’s not mild or stainless steel.
 
Conor Jensen said:
Thank you guys for the replies, still no success yet but it seems it may be in my normalizing cycle that is causing my issue. The normalizing treatment was one Nick Wheeler suggested for 1095 which is 1600,1550,1500,1450, and 1400x3. Then ht at 1475 with a 10 min soak. I have tried quenching in room temp parks 50 and also heated at 100 and 120. I also tried water to see what would happen and still nothing... I am going to try to harden just a scrap piece tomorrow that has had nothing done to it and see what happens. Process of elimination right? If it is the normalizing do you think there is anyway to save these blades? I have treated each one 3 times with different temps for the quench and up to 1500 for the ht on one of them. You guys rock
Click to expand...

That is too many cycles. Once you get past three, you can be refining the grain so much that you cannot get past the pearlite nose, no matter how fast your quench is.

Normalizing is the first cycle. The rest are grain refinement cycles.

Contact me at wjkrywko at gmail dot com, and I will give you my address to send me a sample. I’ll try my protocol and see if it hardens.
 
Maybe I missed it in the thread, but how are you determining that they aren't hardening?
 
You must log in or register to reply here.
Back
Top