1095 Won't Harden?!?

C

Conor Jensen

Joined
Nov 24, 2019
Messages
22
Hi everyone, I have made quite a few knives with 1095 but I recently made a chefs knife (which I had never done before) that is about 1/8 " thick and I can not seem to get the thing to harden. I did a normalizing treatment in my new kiln on it first and when heat treat time came around I had a new batch of park 50 quench oil (heated). Quickly quenched and nothing... Tried another heat treatment a few degrees hotter and still nothing... I have done 3 heat treatments with different temps for kiln and the quench and no luck. I have never had this issue before and would love to figure this out. Also should I give up on this knife after 3 ht? Thanks in advance for any suggestions.
 
Ya, I suppose you’re right. I’ve never had a bad batch from them before. I will order some more and try again.
 
Ask for a batch alloy analysis report. Can you do a spark test to see if it is hardenable? Could request the batch alloy analysis report for the steel they filled your order with. Did your steel have any color coding indicating what kind it was? just some thoughts on how you might tell what you have.
 
Conor Jensen said:
Hi everyone, I have made quite a few knives with 1095 but I recently made a chefs knife (which I had never done before) that is about 1/8 " thick and I can not seem to get the thing to harden. I did a normalizing treatment in my new kiln on it first and when heat treat time came around I had a new batch of park 50 quench oil (heated). Quickly quenched and nothing... Tried another heat treatment a few degrees hotter and still nothing... I have done 3 heat treatments with different temps for kiln and the quench and no luck. I have never had this issue before and would love to figure this out. Also should I give up on this knife after 3 ht? Thanks in advance for any suggestions.
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1650fx 10min, cool to black
1550f,10min, cool to black
1450f, 10min, cool to black

1450-1475f x10min, quench, temper as usual.
 
Willie71 said:
1650fx 10min, cool to black
1550f,10min, cool to black
1450f, 10min, cool to black

1450-1475f x10min, quench, temper as usual.
Click to expand...

Thanks, those are the exact heats I used, unless my temps on my new kiln are off but the one batch of knives I did before this one all worked out fine so I'm not sure whats going on.
 
robwil said:
Ask for a batch alloy analysis report. Can you do a spark test to see if it is hardenable? Could request the batch alloy analysis report for the steel they filled your order with. Did your steel have any color coding indicating what kind it was? just some thoughts on how you might tell what you have.
Click to expand...

Thanks, thats a good idea. I will try to contact them on monday, there is color coding which matches up and they wrote on the steel what it was as usual. Hopefully they can shed some light on it.
 
Get a scrap piece, way too hot, quench in water, see if it gets glass hard brittle

How do you calibrate the kiln temp ?
 
I could try that. What exactly will the results tell me? As for the calibration I’m not sure. I figured it should be good since it’s new but probably worth trying. Thanks
 
Conor Jensen said:
Thanks, those are the exact heats I used, unless my temps on my new kiln are off but the one batch of knives I did before this one all worked out fine so I'm not sure whats going on.
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NJSB has had problems with bad batches of steel. Contact them and they will sort you out.
 
Has nothing to do with your steel not hardening but I thought parks 50 at room temp unless it's very cold out and canola oil at 120?
 
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?
 
Conor Jensen said:
I could try that. What exactly will the results tell me? As for the calibration I’m not sure. I figured it should be good since it’s new but probably worth trying. Thanks
Click to expand...
You asked what getting the metal too hot, then quenching water would tell you? Out of the water and cooled to room temp that metal coupon will break easy. No bending, just break. If the coupon bends much before breaking you can be assured it's not a high carbon steel, but some type of lower carbon that's not knife making quality.

Comments from anybody on this?
 
I the controller set correctly for the type of thermocouple you are using?

have not some others reported problems with inexpensive thermocouples (or something like that)?
 
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.
 
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.
 
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