440B hardness

[DeadboxHero]

I am also based in Europe and it looks like most of the shops carrying knife steel have that high carbon 440b. With oven at 1060°, dry ice bath and temper at 180°C I am reaching about 61 HRC.

I doubt that it is in 65 HRC range, but it might be in 62-63 HRC range.

Hardness chisels with a narrower hardness range could give you a preciser results. Keep your eyes open for a used hardness tester in local classifieds and auction houses.

Hardness chisels don't work very good it comes down to fundamentally how it works things scratch differently for various reasons other than just hardness. So it's not a good way to measure localized resistance to elastic and plastic deformation.

 

[Mac an sealgair]

Thanks for all the answers and advice given, much appreciated. I’m going to retemper the blade on Monday once I’ve finished my run of shifts and take it from there.
Just for a bit of clarity can I point out I’m a hobbiest not a commercial knife maker. I do it for fun. Most of my knifes are give aways and at best material cost recovery. I can’t justify spending thousands of pounds on kilns and hrc testers, certainly not at this point.
My first knife was made from an old file, softened/annealed in a fire and made into a knife shape with an angle grinder and files. It turned out as you might expect but I was proud of it and still have it. From there I bought a 1x30 which served its purpose for a while and my knife making improved enough to make me invest in a 2x72 which was a game changer in the quality of my knives.
The point I’m making is how many of you thought to yourself, I think I’ll make a knife and went out and spent thousands on a kiln, hrc tester, cryo equipment etc? We are all on a journey, our equipment and ability grows through time. But we all have to start from the same place.
Telling someone who is trying to dip his toes that he can’t do it without spending silly money first is just wrong. You can heat treat stainless in a gas forge, you can do it without foil, you don’t kneed to cryo to harden it. All of these things will undoubtedly make it a far superior knife but like my first attempt with the file, it will still be a knife.
I came on here looking for an answer that probably there wasn’t one but the response I got from some on here was somewhat underwhelming for someone looking to learn. That comment isn’t aimed at the majority of of civil comments made and they were appreciated and I have taken them on board, even some of what Devin said, and I apologise to anyone this has offended. Maybe we should all remember where we started and appreciate that we are not all at the same place on our journey.
Thank you for all your help.

 

[DeadboxHero]

Well, not sure what there is to discuss or what advice can be shared if you feel this way.


Luckily, neither is needed if this is the only objective.

Good luck, be safe, have fun.

You can heat treat stainless in a gas forge, you can do it without foil, you don’t kneed to cryo to harden it. All of these things will undoubtedly make it a far superior knife but like my first attempt with the file, it will still be a knife.

 

[BluntCut MetalWorks]

My results with 440b were similar as FredyCro. I've tested a few 62rc 440B blades.

I am also based in Europe and it looks like most of the shops carrying knife steel have that high carbon 440b. With oven at 1060°, dry ice bath and temper at 180°C I am reaching about 61 HRC.

I doubt that it is in 65 HRC range, but it might be in 62-63 HRC range.

Go ahead with experiment & fun, high alloy steels can be harden using a forge + clay coating + freezer. Your above 440B result probably no more than 60-61rc, try scratch test with an old file edge + heavy pressure. A side thought - D2 would yield 64-65rc for given ht above.

Few times a year, there are threads like this posted here and had similar responses/replies - basically "Do proper ht ... or else send to pro HT service". A curious mind would wonder - is it possible to produce 50% repeatable good ht result for high alloy steels using a weed burner + kaowool + satanite + toaster oven + freezer? e.g. 440c 61rc or s30v 62rc or cpm t-15 64rc with good edge stability. If I try, will post a video of ht & edge testing.

Thanks for all the answers and advice given, much appreciated. I’m going to retemper the blade on Monday once I’ve finished my run of shifts and take it from there.
Just for a bit of clarity can I point out I’m a hobbiest not a commercial knife maker. I do it for fun. Most of my knifes are give aways and at best material cost recovery. I can’t justify spending thousands of pounds on kilns and hrc testers, certainly not at this point.
My first knife was made from an old file, softened/annealed in a fire and made into a knife shape with an angle grinder and files. It turned out as you might expect but I was proud of it and still have it. From there I bought a 1x30 which served its purpose for a while and my knife making improved enough to make me invest in a 2x72 which was a game changer in the quality of my knives.
The point I’m making is how many of you thought to yourself, I think I’ll make a knife and went out and spent thousands on a kiln, hrc tester, cryo equipment etc? We are all on a journey, our equipment and ability grows through time. But we all have to start from the same place.
Telling someone who is trying to dip his toes that he can’t do it without spending silly money first is just wrong. You can heat treat stainless in a gas forge, you can do it without foil, you don’t kneed to cryo to harden it. All of these things will undoubtedly make it a far superior knife but like my first attempt with the file, it will still be a knife.
I came on here looking for an answer that probably there wasn’t one but the response I got from some on here was somewhat underwhelming for someone looking to learn. That comment isn’t aimed at the majority of of civil comments made and they were appreciated and I have taken them on board, even some of what Devin said, and I apologise to anyone this has offended. Maybe we should all remember where we started and appreciate that we are not all at the same place on our journey.
Thank you for all your help.

 

[Mac an sealgair]

I still use hrc files myself and find them very useful, but they also have a learning curve and can be very misleading at times. If any file skates over the blade, I’d say it is good to go for your intended use.

Yeh they can be a bit of a pain sometimes. Consistency with pressure and method. They can’t give a spot on measure but are good enough to let you know if your heat treat worked and where your hrc is within a 5 point range. You can narrow that down a bit too by the depth of scratches left, if your at the high or low end of the 5 points. Not accurate but better than nothing

 

[Mac an sealgair]

My results with 440b were similar as FredyCro. I've tested a few 62rc 440B blades.


Go ahead with experiment & fun, high alloy steels can be harden using a forge + clay coating + freezer. Your above 440B result probably no more than 60-61rc, try scratch test with an old file edge + heavy pressure. A side thought - D2 would yield 64-65rc for given ht above.

Few times a year, there are threads like this posted here and had similar responses/replies - basically "Do proper ht ... or else send to pro HT service". A curious mind would wonder - is it possible to produce 50% repeatable good ht result for high alloy steels using a weed burner + kaowool + satanite + toaster oven + freezer? e.g. 440c 61rc or s30v 62rc or cpm t-15 64rc with good edge stability. If I try, will post a video of ht & edge testing.

Thank you Blunt! and Freddy. So my worry was would 440B tempered to 60-61rc not be too brittle? Stacy said right at the start that post quench it should be around that mark and temper down to mid to high 50’s which was the results I was expecting. Obviously you guys are getting a higher RC with your methods but I wasn’t sure about toughness. I don’t need it to be super hard, I just don’t want it to break if it’s dropped etc

 

[FredyCro]

Thank you Blunt! and Freddy. So my worry was would 440B tempered to 60-61rc not be too brittle? Stacy said right at the start that post quench it should be around that mark and temper down to mid to high 50’s which was the results I was expecting. Obviously you guys are getting a higher RC with your methods but I wasn’t sure about toughness. I don’t need it to be super hard, I just don’t want it to break if it’s dropped etc

I would up the temper to 180-200°C, you will lose 1-2 hrc but shoud still be in very usable range. Don't push the edge too thin either.

I appreciate the advice from all the folks here, having guys like D DevinT , Stacy E. Apelt - Bladesmith and other share their knowledge hear for free is awesome. Work within your limits, but be aware of what is the best practice.

Also, you don't need to spend thousands for an oven and hardness tester. I got my oven from ebay for around 300 Euro and tester from local classifieds for about 250 Euro.

 

[DeadboxHero]

Geometry Cuts, that's the reason why good heat treatment is so important, so you can push the geometry to make the knife perform good.

Don't push the edge too thin either.

 

[FredyCro]

Geometry Cuts, that's the reason why good heat treatment is so important, so you can push the geometry to make the knife perform good.

I am sorry for the lame explanation. I was reffering to the coarse carbide structure and carbide tear out that can happen if you push this steel too much (zero or near zero edge).

 

[Mac an sealgair]

I would up the temper to 180-200°C, you will lose 1-2 hrc but shoud still be in very usable range. Don't push the edge too thin either.

I appreciate the advice from all the folks here, having guys like D DevinT , Stacy E. Apelt - Bladesmith and other share their knowledge hear for free is awesome. Work within your limits, but be aware of what is the best practice.

Also, you don't need to spend thousands for an oven and hardness tester. I got my oven from ebay for around 300 Euro and tester from local classifieds for about 250 Euro.

Thats my plan, retemper at a higher temp though I don’t think I’ll go as high as 200.
I’ve been visiting this site for a while now picking up information and learning from the many who are willing to share their knowledge and skills here and I do appreciate them. That’s why I came here to ask my question.
Can I ask what oven you got?was it a proper heat treat oven or a kiln utilised as an oven? I’ve looked at kilns but never sure how useful they’d be or if I was just throwing my money away. And well done getting an hrc tester at that price

 

[FredyCro]

Thats my plan, retemper at a higher temp though I don’t think I’ll go as high as 200.
I’ve been visiting this site for a while now picking up information and learning from the many who are willing to share their knowledge and skills here and I do appreciate them. That’s why I came here to ask my question.
Can I ask what oven you got?was it a proper heat treat oven or a kiln utilised as an oven? I’ve looked at kilns but never sure how useful they’d be or if I was just throwing my money away. And well done getting an hrc tester at that price

I got lucky on an old, used industrial heat treat oven from ebay. Its an all analog 3 kw unit with a 1100°C temp range. Nice door setting and hidden elements. I have all the gadgets ro digitalize it, but i dont plan touching anything as along as it works. Same with the WWII era hardness tester. You will find a thread if you search my post.

Some pics of the oven

https://imgur.com/a/fW5pELJ

 

[Mac an sealgair]

Thanks for that, having a look now.

 

[Mac an sealgair]

I got lucky on an old, used industrial heat treat oven from ebay. Its an all analog 3 kw unit with a 1100°C temp range. Nice door setting and hidden elements. I have all the gadgets ro digitalize it, but i dont plan touching anything as along as it works. Same with the WWII era hardness tester. You will find a thread if you search my post.

Some pics of the oven

https://imgur.com/a/fW5pELJ

How cool is that. You definitely got lucky with both of these. Now you’ve got me interested, especially in an hrc tester. I take it a mechanical one is preferred to an electronic, longevity and easier to maintain etc.

 

[Stacy E. Apelt - Bladesmith]

I'll try and sum up what the advice is here:
1) No one is saying you have to spend !000 £ to make knives. What they are saying is the HT of stainless and high alloy steels should be done by someone with the proper equipment and skills. Those people can be found most anywhere in the world, and the cost will vary from free to maybe 10-15£.

2) The reading you are getting with your files is inaccurate. It could be your testing method, or inexperience with hardness testing, or the files are used up. 440B will not ever get to Rc65.

3) Just because it hardened it does not mean the structures are proper. It could be overly brittle, have huge carbides, or the alloys improperly distributes.

4) Don't worry about all the above. Temper at 180-200°C and finish the blade. It will be whatever hardness it is. Enjoy it and test it by cutting some things. The brass rod test will likely tell you a lot, too.

5) For your next forge HT knives, use a carbon steel. 1080, 1070, 5160, 9260, etc. will all harden easily with few problems in a forge with an oil quench. I don't have the charts available, but I believe rapeseed oil would be a better choice than rye oil.

Over 60 years ago I made my first knife. It was a piece of unknown low carbon steel hammered with a ball peen hammer on the tiny anvil area on the back of a vise while holding it with pliers and using a propane plumbers torch for heat. I hardened it by getting it red (I now know it was not nearly hot enough) and quenching in room temp tap water. The handle was a piece of weathered out white-tail deer antler, and the pins were 16-penny nails. The handle looked terrible, so I burned it with the torch to darken it. I was proud as heck with it! I still am, as it was the very best I could do with my primitive equipment and 0$/£ budget. You work with what you have and grow as you can.
I still have it and put it on the table at knife shows. Everyone starts somewhere. Most of us start with many errors. We improve over time and learn from our mistakes.
Avoiding future mistakes is one of the biggest helps from Shop Talk, as you can learn what to do and not to do before doing it.

 

[Mac an sealgair]

I'll try and sum up what the advice is here:
1) No one is saying you have to spend !000 £ to make knives. What they are saying is the HT of stainless and high alloy steels should be done by someone with the proper equipment and skills. Those people can be found most anywhere in the world, and the cost will vary from free to maybe 10-15£.

2) The reading you are getting with your files is inaccurate. It could be your testing method, or inexperience with hardness testing, or the files are used up. 440B will not ever get to Rc65.

3) Just because it hardened it does not mean the structures are proper. It could be overly brittle, have huge carbides, or the alloys improperly distributes.

4) Don't worry about all the above. Temper at 180-200°C and finish the blade. It will be whatever hardness it is. Enjoy it and test it by cutting some things. The brass rod test will likely tell you a lot, too.

5) For your next forge HT knives, use a carbon steel. 1080, 1070, 5160, 9260, etc. will all harden easily with few problems in a forge with an oil quench. I don't have the charts available, but I believe rapeseed oil would be a better choice than rye oil.

Over 60 years ago I made my first knife. It was a piece of unknown low carbon steel hammered with a ball peen hammer on the tiny anvil area on the back of a vise while holding it with pliers and using a propane plumbers torch for heat. I hardened it by getting it red (I now know it was not nearly hot enough) and quenching in room temp tap water. The handle was a piece of weathered out white-tail deer antler, and the pins were 16-penny nails. The handle looked terrible, so I burned it with the torch to darken it. I was proud as heck with it! I still am, as it was the very best I could do with my primitive equipment and 0$/£ budget. You work with what you have and grow as you can.
I still have it and put it on the table at knife shows. Everyone starts somewhere. Most of us start with many errors. We improve over time and learn from our mistakes.
Avoiding future mistakes is one of the biggest helps from Shop Talk, as you can learn what to do and not to do before doing it.

View attachment 1785445

Thanks for the good advice Stacy, and by everyone else. My frustrations were trying to get my points across. I’m not a master knife maker and don’t pretend to be but I’ve been making knives for 3 years, all of them from carbon steels, mostly O1 and 80CRV2 so I do have a little knowledge. My forge is set up with thermocouples and a muffle. Not as convenient or accurate as an electric kiln but I enjoy tweaking and playing about with it and get good heat treats from it. Still not ideal for stainless I know but you’ve got to try eh.
It’s the first time I’ve done anything with stainless and am just playing about with it. I knew my setup wasn’t right but with this particular knife the quality wasn’t as important as say a chefs knife. It’s a sgian dubh, it won’t see any work, or even be sharpened and will just be another addition to my own collection and possibly worn next time I wear a kilt depending how it turns out. I was surprised about what I thought was the hardness of it when I tested it and came on here to see if anyone had a similar experience using this steel. What you told me right at the start about quench hardness was one of the things I wanted to know. I was questioning my temper though more than the hardness.
My problem with Devin wasnt so much what he was saying but the way he was saying it. I didn’t come here to fall out with anyone though so if he’s reading this, my apologies. If you were closer I’d buy you beer and laugh about it
Anyway. Now that I’ve had a bit more time and looked at it again, you guys were right, it wasn’t 65hrc, closer to 60. I’ve retempered it just for peace of mind and got it around mid 50s, well according to my files anyway. My worry was about it being too hard and brittle. As for carbides etc, that had crossed my mind too. I considered breaking it but didn’t see the point. It was a substandard heat treat so wasn’t going to tell me anything.
By the way Rye Oil 32 is a quench oil, not a cooking oil. Rye oil is just a brand name, they do all different types of oil. It’s a UK equivalent to Parks AAA, which isn’t easy to get here and quite expensive. It is the recommended quench oil given by the steel supplier and what I use on my carbon knives.
FredyCro’s hrc tester pricked my interest though and got me searching. I’m now waiting on a guy getting back about shipping costs and I might have a new toy
Thanks again to everyone for their input, as much as it might not have looked like it at times, it was much appreciated.

 

[DevinT]

Thanks for the good advice Stacy, and by everyone else. My frustrations were trying to get my points across. I’m not a master knife maker and don’t pretend to be but I’ve been making knives for 3 years, all of them from carbon steels, mostly O1 and 80CRV2 so I do have a little knowledge. My forge is set up with thermocouples and a muffle. Not as convenient or accurate as an electric kiln but I enjoy tweaking and playing about with it and get good heat treats from it. Still not ideal for stainless I know but you’ve got to try eh.
It’s the first time I’ve done anything with stainless and am just playing about with it. I knew my setup wasn’t right but with this particular knife the quality wasn’t as important as say a chefs knife. It’s a sgian dubh, it won’t see any work, or even be sharpened and will just be another addition to my own collection and possibly worn next time I wear a kilt depending how it turns out. I was surprised about what I thought was the hardness of it when I tested it and came on here to see if anyone had a similar experience using this steel. What you told me right at the start about quench hardness was one of the things I wanted to know. I was questioning my temper though more than the hardness.
My problem with Devin wasnt so much what he was saying but the way he was saying it. I didn’t come here to fall out with anyone though so if he’s reading this, my apologies. If you were closer I’d buy you beer and laugh about it
Anyway. Now that I’ve had a bit more time and looked at it again, you guys were right, it wasn’t 65hrc, closer to 60. I’ve retempered it just for peace of mind and got it around mid 50s, well according to my files anyway. My worry was about it being too hard and brittle. As for carbides etc, that had crossed my mind too. I considered breaking it but didn’t see the point. It was a substandard heat treat so wasn’t going to tell me anything.
By the way Rye Oil 32 is a quench oil, not a cooking oil. Rye oil is just a brand name, they do all different types of oil. It’s a UK equivalent to Parks AAA, which isn’t easy to get here and quite expensive. It is the recommended quench oil given by the steel supplier and what I use on my carbon knives.
FredyCro’s hrc tester pricked my interest though and got me searching. I’m now waiting on a guy getting back about shipping costs and I might have a new toy
Thanks again to everyone for their input, as much as it might not have looked like it at times, it was much appreciated.

Thanks

Hoss

 

[Stacy E. Apelt - Bladesmith]

Thanks for the explanation of Rye oil. That is good info for other UK and EU folks.

Enjoy making your knives and don't worry too much about how hard they are and such.

 

[BluntCut MetalWorks]

Well, I'd tried... ** Note: This is a Demo of possibility without showing 'how' to achieve the result **

It is possible to HT using a weed burner + Toaster Oven + Freezer and produce good quality blades.

S30V 62.5rc, 15 DPS, BET less than 0.010"
440C 61rc, 15 DPS, BET less than 0.010"

Edge Stability Test: Whittle Bamboo; Argentine Lignum Vitae; Cut & Chop rope on beef rib bone backing; whittle elk antler tip

Result: Both Passed!

My results with 440b were similar as FredyCro. I've tested a few 62rc 440B blades.


Go ahead with experiment & fun, high alloy steels can be harden using a forge + clay coating + freezer. Your above 440B result probably no more than 60-61rc, try scratch test with an old file edge + heavy pressure. A side thought - D2 would yield 64-65rc for given ht above.

Few times a year, there are threads like this posted here and had similar responses/replies - basically "Do proper ht ... or else send to pro HT service". A curious mind would wonder - is it possible to produce 50% repeatable good ht result for high alloy steels using a weed burner + kaowool + satanite + toaster oven + freezer? e.g. 440c 61rc or s30v 62rc or cpm t-15 64rc with good edge stability. If I try, will post a video of ht & edge testing.

 

[Mac an sealgair]

Nice one, cant believe youve done that and Im still not finished my wee knife
So what would be the failings on these knives. Im guessing grain/carbide growth and retained austenite but if theyre holding an edge would that matter for an edc? Fit for purpose?
Look forward to seeing what happens if you narrow the edge angles. Thats what Deadbox hero was talking about with geometry and the need for proper heat treat. Be interesting to see how far you can take them before they fail.

 

[BluntCut MetalWorks]

Nice one, cant believe youve done that and Im still not finished my wee knife
So what would be the failings on these knives. Im guessing grain/carbide growth and retained austenite but if theyre holding an edge would that matter for an edc? Fit for purpose?
Look forward to seeing what happens if you narrow the edge angles. Thats what Deadbox hero was talking about with geometry and the need for proper heat treat. Be interesting to see how far you can take them before they fail.

Even with top-notch ht: 15dps Edge whittles elk antler is quite a challenging test. It requires high strength and full elastic range in order to dig into the antler w/o deformation/failure. This is something easily test by anyone.

RA (fcc structure) isn't strong nor has full elasticity range. Grain growth is almost not a concern for high alloy steels because there are copious amount of grain pinning element/particle in solution (aust matrix).

Just to be clear - for this demo, I applied part of my R&D sequencing IP, hence won't disclose the 'how'. Although using simple tools (weed burner, toaster oven, freezer), complex technique were conducted. Perhaps point being, barrier to entry - equipment wise - is low. You've better setup, so now just matter of think & tinker.

Here is S30V 62.5rc with 13.5dps edge performs same tests - result: passed!