Steel hardening

peterk123

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Curious if you guys know who does the steel hardening. Does the knife maker do it or does it come prehardened or sent out somewhere after the blanks are cut? Seems like this is one of the most critical parts so I would expect the knife maker should be the one. Otherwise, a blade is just a blade, right?
 
So do the knife makers have their own specifications or is X degrees used for Y amount of time based on the type of steel?
Typically the steel producers will have a recommended process. Here's an example from Crucible Industries for their 3V, a common premium alloy for knives:

Crucible Selector - CPM® 3V.
 
So do the knife makers have their own specifications or is X degrees used for Y amount of time based on the type of steel?

Typically the steel producers will have a recommended process. Here's an example from Crucible Industries for their 3V, a common premium alloy for knives:

Crucible Selector - CPM® 3V.
What mountain said. There is some wiggle room depending on steel and the end use. You might want to play around with bainite in carbon steels or you might want to keep the temper down to have a super high hardness for a chefs knife.
Secondary tempering temperatures offer some trades offs without losing RC hardness.

Overall it’s a recipe though. Ramp at a specific rate to a specific temp. Hold. Maybe be ramp up and hold again. Then quench. Cryo if need be. Then temper.
 
Actually, the reason I was asking was whether or not one knife maker is really that much better than the next. If heat treating is outsourced or based on steel manufacturer specs, then at the end of the day it does not seem to matter that much. Steel is steel, so a small one man operation could put out a blade just as good as Benchmade, for example.

We put a lot of emphasis on sharpness, but that is temporary if you use your knife and it is really on you to keep it sharp.

Thoughts?
 
Actually, the reason I was asking was whether or not one knife maker is really that much better than the next. If heat treating is outsourced or based on steel manufacturer specs, then at the end of the day it does not seem to matter that much. Steel is steel, so a small one man operation could put out a blade just as good as Benchmade, for example.

We put a lot of emphasis on sharpness, but that is temporary if you use your knife and it is really on you to keep it sharp.

Thoughts?
Kind of.
One custom maker might see heat treatment as a simple necessary process and put more effort into different steps.

Another maker could be a retired metal allergist that puts just as much into his heat treatment as he does to the rest of his work.

Same goes for a big production company. Does Buck have an interest in keeping the hardness down by a few points so that they can avoid chipping damage? Which could result in a chunk of steel in somebody’s eye? At the very least results in a lot of knives returned for repairs or replacement.

I’ve definitely sharpened S30V blades that were nowhere near as hard as what they should be.

I guess what I’m saying is just like every process in knife making it comes down to an individual or companies desire to do it the right way and their budget to invest in the proper equipment to do so.
 
Kind of.
One custom maker might see heat treatment as a simple necessary process and put more effort into different steps.

Another maker could be a retired metal allergist that puts just as much into his heat treatment as he does to the rest of his work.

Same goes for a big production company. Does Buck have an interest in keeping the hardness down by a few points so that they can avoid chipping damage? Which could result in a chunk of steel in somebody’s eye? At the very least results in a lot of knives returned for repairs or replacement.

I’ve definitely sharpened S30V blades that were nowhere near as hard as what they should be.

I guess what I’m saying is just like every process in knife making it comes down to an individual or companies desire to do it the right way and their budget to invest in the proper equipment to do so.
Makes sense. Probably why some users will say brand X wouldn't hold an edge, while another says it is the best ever. Quality control. Or lack thereof.
 
Makes sense. Probably why some users will say brand X wouldn't hold an edge, while another says it is the best ever. Quality control. Or lack thereof.
Exactly. Think of it like a rifle. They all have specs that they need to meet for chamber and barrel dimensions. Some do it better than others.
Some that cost more end up being lower quality or less accurate than a budget rifle
 
IME/IMO, once a maker gets to a certain output volume, they tend to bring the heat treat and tempering process in house. It all depends on when they can justify the equipment expense. It shortens their time from start to finish for a blade as well. Since they no longer need to send blades out to another location for the process. Plus they gain additional quality control over the final product.

As already mentioned, some makers will be over the top in how they perform the task. Others will be less stringent on things. Generally speaking though, the temperatures involved are pretty set (small variances are allowed) for the hardening process. Quench methods depend on what steel is being processed. You won't process O1 or 5160 the same as ATS34, D2 or one of the newer stainless super steels. Some steels also benefit from a cryogenic process where others either won't, or it won't be enough of a benefit to justify the additional steps.

From what I've seen of things, over the decades, the heat treat ovens have gotten a lot better, and might not be as crazy expensive (haven't looked in some time). What happens to the steel is a bit interesting during the different stages. Tempering a blade is a critical step too. Since if you don't, then the result is something very hard, but brittle (easy to break/damage). Often the desired hardness numbers are determined by what the blade will be used for.

All of the needed information is typically published for an alloy. What temperature to harden at for how long, followed by what quench method is needed. Then they'll give what temperature to temper the item at (also for how long IIRC) to get to the desired end hardness.

BTW, edge retention can be ruined if a blade edge is ground so that heat is created/transferred to the edge. This is one of the reasons I'll never use one of the belt driven sharpening items (worksharp). You have to be very careful when using such items in order to keep the edge cool enough to NOT screw up the heat treatment that's been applied. I'll gladly spend the time to sharpen my blades with the setup I have knowing that zero heat is going to the edge during the process.
 
Actually, the reason I was asking was whether or not one knife maker is really that much better than the next. If heat treating is outsourced or based on steel manufacturer specs, then at the end of the day it does not seem to matter that much. Steel is steel, so a small one man operation could put out a blade just as good as Benchmade, for example.

We put a lot of emphasis on sharpness, but that is temporary if you use your knife and it is really on you to keep it sharp.

Thoughts?

Depends on a number of factors- some blade makers or commercial heat treaters may take the time to follow the best process and/or may have the optimum equipment to do it. A blade maker who farms out the heat treat may have a very specific process to follow or might just request "60 HRc" etc. Some may have developed that 'black art' for given alloys and blade profiles that creates an unusually high performing blade.

Some may be all about the cost and productivity, with 'OK' results.

Consider the art of the ancient Japanese sword smiths. There's a legend that a master lopped off an apprentice's hand when said apprentice was caught checking the temperature of the quench water. They were making incredibly sharp and tough blades forged from thousands of layers of steel and composite structures with an extremely hard and sharp edge, medium hard and tough sides, and very tough but not necessarily hard cores and backs. Their raw materials were collected in the wild. This technology goes back to the 7th century give or take.
 
IME/IMO, once a maker gets to a certain output volume, they tend to bring the heat treat and tempering process in house. It all depends on when they can justify the equipment expense. It shortens their time from start to finish for a blade as well. Since they no longer need to send blades out to another location for the process. Plus they gain additional quality control over the final product.

As already mentioned, some makers will be over the top in how they perform the task. Others will be less stringent on things. Generally speaking though, the temperatures involved are pretty set (small variances are allowed) for the hardening process. Quench methods depend on what steel is being processed. You won't process O1 or 5160 the same as ATS34, D2 or one of the newer stainless super steels. Some steels also benefit from a cryogenic process where others either won't, or it won't be enough of a benefit to justify the additional steps.

From what I've seen of things, over the decades, the heat treat ovens have gotten a lot better, and might not be as crazy expensive (haven't looked in some time). What happens to the steel is a bit interesting during the different stages. Tempering a blade is a critical step too. Since if you don't, then the result is something very hard, but brittle (easy to break/damage). Often the desired hardness numbers are determined by what the blade will be used for.

All of the needed information is typically published for an alloy. What temperature to harden at for how long, followed by what quench method is needed. Then they'll give what temperature to temper the item at (also for how long IIRC) to get to the desired end hardness.

BTW, edge retention can be ruined if a blade edge is ground so that heat is created/transferred to the edge. This is one of the reasons I'll never use one of the belt driven sharpening items (worksharp). You have to be very careful when using such items in order to keep the edge cool enough to NOT screw up the heat treatment that's been applied. I'll gladly spend the time to sharpen my blades with the setup I have knowing that zero heat is going to the edge during the process.
Larger the oven, the more difficult it becomes to control temperatures within all zones. Bigger could be better, but that depends.
 
Larger the oven, the more difficult it becomes to control temperatures within all zones. Bigger could be better, but that depends.
Ovens should be sized for batch sizes. Or size the batches according to oven size. Better to start off with a smaller oven when you're just starting out. Well, unless you plan to fill it up each time. Then again, that's probably just being logical/smart. You wouldn't use an oven that can handle 100 blades for just a few. Well, unless that's the only oven you have. I would also hope that the oven would not have any cool spots inside it that would impact the process. I can't imagine there being many air circulation fans that could hold up to heat treatment oven temperatures without failing.
 
IME/IMO, once a maker gets to a certain output volume, they tend to bring the heat treat and tempering process in house. It all depends on when they can justify the equipment expense. It shortens their time from start to finish for a blade as well. Since they no longer need to send blades out to another location for the process. Plus they gain additional quality control over the final product.

As already mentioned, some makers will be over the top in how they perform the task. Others will be less stringent on things. Generally speaking though, the temperatures involved are pretty set (small variances are allowed) for the hardening process. Quench methods depend on what steel is being processed. You won't process O1 or 5160 the same as ATS34, D2 or one of the newer stainless super steels. Some steels also benefit from a cryogenic process where others either won't, or it won't be enough of a benefit to justify the additional steps.

From what I've seen of things, over the decades, the heat treat ovens have gotten a lot better, and might not be as crazy expensive (haven't looked in some time). What happens to the steel is a bit interesting during the different stages. Tempering a blade is a critical step too. Since if you don't, then the result is something very hard, but brittle (easy to break/damage). Often the desired hardness numbers are determined by what the blade will be used for.

All of the needed information is typically published for an alloy. What temperature to harden at for how long, followed by what quench method is needed. Then they'll give what temperature to temper the item at (also for how long IIRC) to get to the desired end hardness.

BTW, edge retention can be ruined if a blade edge is ground so that heat is created/transferred to the edge. This is one of the reasons I'll never use one of the belt driven sharpening items (worksharp). You have to be very careful when using such items in order to keep the edge cool enough to NOT screw up the heat treatment that's been applied. I'll gladly spend the time to sharpen my blades with the setup I have knowing that zero heat is going to the edge during the process.
It's interesting you bring up the issue of heat when sharpening. I used to always use stones but got sick of doing a half dozen knives at once. So got a worksharp. I can run it real slow so it shouldn't heat the steel. But, given that my wife upgraded my blades, I just ordered some diamond stones and a new strop. The worksharp does a great job but I actually can do a better job with stones. Just takes longer.
 
It's interesting you bring up the issue of heat when sharpening. I used to always use stones but got sick of doing a half dozen knives at once. So got a worksharp. I can run it real slow so it shouldn't heat the steel. But, given that my wife upgraded my blades, I just ordered some diamond stones and a new strop. The worksharp does a great job but I actually can do a better job with stones. Just takes longer.
I've been using the Wicked Edge (Pro Pack 1) I picked up since 2019 to sharpen all my blades. LOVE the setup. Picked up the 1500/220 stone set as well. Never used the strops due to that. I find that if I hit blades about every three months (for my kitchen knives), depending on use level, then they retain a razor edge. Takes maybe ten minutes on my longer blades (over 6") to do that. Which means I spend no more than an hour every few months on edge maintenance.

I really like the adjustability of my setup for blade edge angle. I also like how the blade is held edge up, and then you run the [diamond] stones over it. No need to use much pressure/force while doing it too. I have found that long, flexing blades don't sharpen as well. But I've not really found any setup that did well with those anyway (that I'd use at least).

Something else to keep in mind for the worksharp setup. The belts WILL wear as you use them. Faster for higher hardness steels. Plus there's a higher chance of the belt accumulating any previous metals run against them. Meaning if you run any non-stainless blades against it, you run the chance of embedding particles of that steel into your stainless blades.

I'm sure the worksharp setup is fine for some people. I just care for my blades more than that. ;) Most of mine cost at least $100 to purchase. I have a Shun Kaji slicer that goes for well over $200. NFW am I not taking great care of that.
 
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