kitchen knives after quench and tempering.

Fred.Rowe

Fred.Rowe

Joined
May 2, 2004
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The information supplied by fellow makers supported a good outcome. These blades were forged from W2 steel. I forged them pretty much to shape, the bevels were set and the distal taper was in the profile. I used room temp Parks 50, around 80 fh to quench these very thin kitchen blades. The thickest was at .098 at the spine plunge intersection. The thinnest of them was the one on top, second pic down, it was at .086 at the plunge spine intersection. The boning knife second from the bottom, same pic, had a long warp in it, end to end ; it took 3 heats at 450 clamped to a section of angle to get it straight.. I like the Brownell's liquid anti scale for a heat blocking agent. It goes on easier than clay. There were a couple of small ribbon warps along the edge but nothing that could not be dealt with on the grinder. I did a little re-profiling after heat treat. Keeping them at .125 at the spine plunge junction is something I'll shoot for from now on. The longest blade is 9 1/2 inches, shoulders to tip for scale. Thanks again for your input, I learned something here. Fred

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First of all, at 130F, your Parks 50 is around 10 degrees ABOVE the listed operating range. You shouldn't be heating that stuff unless the ambient temp in your show is below 70F. I would also be hesitant to grind bevels before quenching on any stock that thin, but you have already done it. Beyond that, treat them like you would any blade. I will warn you that if the blade is still hot enough to burst into flames when you bring it out, it may "auto temper" to a slight degree. I had that happen where the same customer bought two kitchen knives from me and he said one was slightly softer than the other and the softer one was the one that had flamed up coming out of the quench.
 
jdm61 said:
First of all, at 130F, your Parks 50 is around 10 degrees ABOVE the listed operating range. You shouldn't be heating that stuff unless the ambient temp in your show is below 70F. I would also be hesitant to grind bevels before quenching on any stock that thin, but you have already done it. Beyond that, treat them like you would any blade. I will warn you that if the blade is still hot enough to burst into flames when you bring it out, it may "auto temper" to a slight degree. I had that happen where the same customer bought two kitchen knives from me and he said one was slightly softer than the other and the softer one was the one that had flamed up coming out of the quench.
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I'll forge them thicker on the next run, but I have to deal with these four. Its all a learning experience or thats how I look at it. That makes sense on the flame up. I'll quench the first one that is the least favored, time it and see. I hadn't thought about the auto temper. The aluminum would be affected @ 1100 or 1200 but I think I want to be at around 700 or 750 before moving to the clamp. Thanks for the insight. I'll be painting them in the morning and quenching in the afternoon.
As to the temp of the quench I'm thinking top end so as not to shock the steel anymore than necessary. I don't have a temp table on the 50 so thanks for that as well. If they go full pretzel on me I'll let you know, if I'm successful I'll let you know as well.

Regards, Fred
 
Fred,
I do what you are talking about with thin W2 blades. I quench in rom temp #50 and count to eight. I pull the blade, quickly straighten any severe warp twist with gloved hands, and stick the blade in my quench plates. I get things ready for the next quench and just flip the blade out of the plates when I put the next one in. A thin W2 blade is cooled to below 400°F in probably 10-20 seconds in the plates.


With W2, the pearlite nose is past in one second.....or the blade will end up soft.
 
Stacy E. Apelt - Bladesmith said:
Fred,
I do what you are talking about with thin W2 blades. I quench in rom temp #50 and count to eight. I pull the blade, quickly straighten any severe warp twist with gloved hands, and stick the blade in my quench plates. I get things ready for the next quench and just flip the blade out of the plates when I put the next one in. A thin W2 blade is cooled to below 400°F in probably 10-20 seconds in the plates.


With W2, the pearlite nose is past in one second.....or the blade will end up soft.
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If I can get these thin ones through the process I'll have learned something. It's one thing I really like about this craft, always learning, always adapting.

Thanks for input Stacy! Fred
 
I have been making bare bones kitchen knives for the local farmers market where I sharpen for a couple years-stock is L6 bandsaw blade (the blade is 14" wide-it's impressive) and maybe 3/32". I cut the profile and heat treat before I grind anything, and straighten right out of the quench (stump and light hammer blows), then back into the quench. Hardening stuff that thin that already has bevels ground can be a pretty grim proposition in my experience-amon other things different cooling rates in the cross section tend to cause cracks (my experience at least).
Helps to differential harden with a torch-that way the spine doesn't contract as much and pull the edge around.
 
J W Bensinger said:
I have been making bare bones kitchen knives for the local farmers market where I sharpen for a couple years-stock is L6 bandsaw blade (the blade is 14" wide-it's impressive) and maybe 3/32". I cut the profile and heat treat before I grind anything, and straighten right out of the quench (stump and light hammer blows), then back into the quench. Hardening stuff that thin that already has bevels ground can be a pretty grim proposition in my experience-amon other things different cooling rates in the cross section tend to cause cracks (my experience at least).
Helps to differential harden with a torch-that way the spine doesn't contract as much and pull the edge around.
Click to expand...

I appreciate your input. This is as thin as I've done. I've got a lot of years experience but in some things even that doesn't count for much. I'm painting with clay, tang and spine leaving the edge clear. It may reduce the thermal shock enough to keep the blades from cracking. We'll see :( :)


I'll post and let you know if I pulled it off, Fred
 
Fred.Rowe said:
If I can get these thin ones through the process I'll have learned something. It's one thing I really like about this craft, always learning, always adapting.

Thanks for input Stacy! Fred
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Fred, I've done the same thing with W2 (from Don's stash), in even thinner cross-sections, I've got one that's being finished at 0.060 spine above the choil.

I quench in room temp parks, to the three count. 1 one-thousand, 2 one-thousand, 3 one-thousand, heavily slicing in the oil during that time, pull out with a cloud of smoke but usually no flair ups. It doesn't take any longer than this on blades this thin, as long as you're fully submerging.


The advantage of clay coated W2 at these thicknesses is that straightening is a breeze, and can be done by hand bending. The disadvantage is that they'll ribbon if the edge is too thin proportionally.
 
My eight count is pretty fast - one-two-three-four......eight....out of the oil. Probably only four-five seconds.
 
Stacy E. Apelt - Bladesmith said:
My eight count is pretty fast - one-two-three-four......eight....out of the oil. Probably only four-five seconds.
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That sounds about right Stacy. Just have to be in there long enough to keep it from recombusting when you bring it out. Although the fireball is always good for a laugh. ;)
 
My experience with W2 has been the same- that it's really the proportional difference between edge and spine thickness that makes a big difference. Too thin an edge for the spine will usually heat much faster, even if a lot of care is taken, and ripple warp incurably.
I like the hot-straighten with gloved hands route, too. Then shimmed temper cycles to take care of any remaining problems.
 
Thank you gentlemen, I'll be taking the plunge, or the steel will be, tomorrow. I'll post the results.

Regards, Fred
 
If you are using clay, add a couple of seconds to the quench before you pull the blade out because you increase the chance of a flare up due to the clayed up part holding heat for longer. I just remembered that is what happened to me that time I was talking about. The first blade that stayed harder was not clayed up as it was my first real attempt to do a big kitchen blade from W2 and I kept it simple and end3e up just polishing it up real nice and purty.
 
jdm61 said:
If you are using clay, add a couple of seconds to the quench before you pull the blade out because you increase the chance of a flare up due to the clayed up part holding heat for longer. I just remembered that is what happened to me that time I was talking about. The first blade that stayed harder was not clayed up as it was my first real attempt to do a big kitchen blade from W2 and I kept it simple and end3e up just polishing it up real nice and purty.
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That's a good point!


Depending on what clay you use, some will just explode off the blade once it hits the quench, but some has to be scraped off later and will retain heat. I was differentially hardening with mine, no clay, so definitely consider this factor in your count.
 
I'm not experienced with w2 or clay coatings, but I do make a lot of similar knives.
Can you explain how plates would do anything besides keep the spine straight?
Most of the warping issues I have are with the tapered tip area, or cupping/waving on a ground bevel. How would a plate help with that?
Fortunately, straightening on a dead flat anvil with a mallet or soft hammer, or a somewhat domed very small ball peen is a breeze...but it's something I did for a decade of smithing before trying it on knife blades.
This is something I've always wondered about- when using aluminum to cool stainless steels after austenitizing, I found out pretty quickly that a blade that's distally tapered both ways and beveled is going to do whatever it wants between plates.
Thanks for your help in understanding this!
 
javand said:
That's a good point!


Depending on what clay you use, some will just explode off the blade once it hits the quench, but some has to be scraped off later and will retain heat. I was differentially hardening with mine, no clay, so definitely consider this factor in your count.
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That is a good point. I'm using Brownell's antiscale liquid for the clay. I've been using it for about a year and prefer it over Satinite or other stiffer materials. It can be painted on quite thin and placed on the blade in delicate patterns. It does explode of the blade when it hits the quench. I might try the first one spine first and see if that works.

elementfe said:
I'm not experienced with w2 or clay coatings, but I do make a lot of similar knives.
Can you explain how plates would do anything besides keep the spine straight?
Most of the warping issues I have are with the tapered tip area, or cupping/waving on a ground bevel. How would a plate help with that?
Fortunately, straightening on a dead flat anvil with a mallet or soft hammer, or a somewhat domed very small ball peen is a breeze...but it's something I did for a decade of smithing before trying it on knife blades.
This is something I've always wondered about- when using aluminum to cool stainless steels after austenitizing, I found out pretty quickly that a blade that's distally tapered both ways and beveled is going to do whatever it wants between plates.
Thanks for your help in understanding this!
Click to expand...

Thanks for adding to the conversation.

The aluminum plates are mounting on a pattern makers vise and are adjustable. They can be set to align with both the distal taper and the blades bevel. The blades are flat ground so when they are pressed between the plates the aluminum surface lies flat against the blades surface.
There were a few years where I was making quite a few big bowies and the adjustable plates were built to in order to keep these long blades straight. My visions not great and does not pick out the lines along the blade when its removed from the quench so the plates help to offset that.

Thanks again for the input guys its much appreciated. I was going to harden these yesterday but my outdoor stove blew a pipe fitting and that took up the day to repair.

Regards, Fred
 
Very cool, thank you, Fred.
I was comparing my primitive approach to a much more thoughtful one, thanks for the great ideas!
 
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