"depending on the application of the blade"

Chris623

Chris623

Well-Known Member
I don't understand this statement...........depending on the application of the blade, when it comes to tempering. Is there a chart that shows application and how to alter for that application?
 
This is going to be dependent on the type of steel and the geometry of the blade. But the point of the axiom you are asking about is to tailor the heat treat hardness for the intended use. Harder is typically for edge retention and softer for toughness and impact resistance. (in VERY general terms)

For example, AEBL stainless performs best around 60-62 Rc. But in a pocketknife the spring would be tempered down considerably softer than that so that it will b springy and not brittle.

Likewise, you probably don’t want a camp chopper to be at 62 or the edge will chip or break when you chop with it. So you’ll sacrifice extreme edge stability in order to get more toughness. The difference between a sushi knife and a bowie knife. The bowie doesn’t require a paper thin razor’s edge and therefore doesn’t need (nor want) insane hardness to hold the intended edge.

Keep in mind, I’m talking in big, round figurative terms for the sake of explanation of the principle.
 
Okay, I realize my question was pretty broad. Let's say I'm making a camp chopper (since you brought it up) and I want a tool that will hold an edge under that kind of abuse. Lets say I'm using 1084. (beginners steel..........and I'm a beginner) :D The data here on the site says:

Heat Treat;
1. Heat to ~1500 degrees F.
2. Quench in oil.
3. Temper twice, for 2 hours each time, anywhere between 350 & 475 depending on the application of the blade.

So the "application" would be for pretty heavy abuse. Would I temper at a higher or lower range of that suggested? And if so, why? In other words, how do those two temps affect the steel during tempering?

And lets say I wanted to make an EDC with the same material. What would the "intended application" be and what temperature would I be needing to temper?
 
Take a look at this link, down at bottom of page: http://www.cashenblades.com/steel/1084.html

There you'll see 1084 should have an as quenched hardness around 66 or so Rc, but tempered at 400F it will be around 60-61 Rc. For a camp chopper you might wish to temper at 450F for 57-58 Rc, or even at 500F for 55-56 Rc. 56 Rc might seem soft, but for a really tough blade for chopping it might be pretty good.
 
Thank you, Ken, that will help all this stuff make better sense to my feeble brain.

So if I were using 1084 to make a carving knife.............where edge holding is important, I'd want to temper at the lowest temperature, correct?
 
Thanks for that comment. I can control my tempering temps to + or - 1 degree because my oven is run by a PID. However my heating temps (I heat with a hand-held torch) are dependent on a magnet! Wish I had a propane forge operated by a PID.
 
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Chris623 said:
Thank you, Ken, that will help all this stuff make better sense to my feeble brain.

So if I were using 1084 to make a carving knife.............where edge holding is important, I'd want to temper at the lowest temperature, correct?
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Yes. Or at least that’s how I’d make the first one, and then I’d do a fair amount of real-world testing by using the knife as intended. See how it does, how the edge holds up, how hard it is to sharpen, etc. Only by using it will you actually know- and here’s why: Hardness doesn’t tell the whole story. It’s a theoretical starting point.

Kitchen knives are a better example because the feedback (edge failure) is pretty immediate. Japanese knives tend to be a lot thinner and lighter than European knives. They also tend to be much sharper. (Sharper because the edge is thinner.) To hold this super thin edge they are tempered to be much harder. The trade off is this makes the edge brittle and chippy. So you are trading durability for cutting performance.

So let’s say you make two kitchen knives from 1084. You temper them separately, one to 62 and the other to 58. You sharpen them the same way- laser sharp.

Hypothetically, the knife hardened to 62 holds the edge quite a bit longer than the 58 knife. Once they both go dull you inspect the edges. The 58 knife edge is softer and rolled over. You run it across a steel or a strop and straighten it and the knife goes back to being sharp again. Whereas the 62 knife is dull because most of the edge is missing. There are toothy little chips all along the edge. It will have to go back to the stones to restore the edge.

This is where you make your decision. Do you want a knife that is constantly in a state of going dull, but can be brought back fairly easily? Or do you want a knife that cuts like a laser until it fails and has to be resharpened?

This is a simplified explanation but the point is that it’s up to you. Now that you tested the knives and figured out what you prefer, you refer back to that chart Ken posted and you use that as your temp reference to harden accordingly to get the results you want for future knives.
 
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Another thing, Chris. You refer to 1084 as a beginner steel. Don’t fall into that trap. Of all the things that make a good knife, the type of steel is waaaayyy down the list. There’s no magical formula for a successful knife. Any steel heat treated well will outperform “super steel” that isn’t.

Pick the type of steel for the attributes it offers. The primary attribute is whether or not you can heat treat it properly. That’s all “simple” steel means... that it’s not a high alloy steel that requires special equipment to treat.

Other attributes are things that make it good for the intended use such as impact resistance, corrosion resistance, edge holding, toughness, etc.
 
Depending on the application of the blade
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In a nutshell, time and experience are the key factors in understanding that statement. The difference between a KSO (Knife Shaped Object), and a Quality cutting tool is the understanding of the many factors that go into it. The information most available on heat treating numbers and times is merely a starting point. As you gain experience, you will start to understand that steel type, COMBINED with heat treatment, COMBINED with geometry, COMBINED ALL the other factors that you, as the knifemaker put into the knife's creation, down to the tiny details, is what makes the difference(s).

These factors can be from slightly, to significantly different based on the end application.... Kitchen, hunter, chopper, campe, fighter, survival, etc all have certain aspects that are desired based on the end use.

For example..... a kitchen knife is generally thin, and can often be much harder, as it's expected to slice, and maybe some mild chopping..... where as a camp/chopper should be slightly to significantly softer to absorb the abuse of hacking on things in an outdoor environment.

This is all due to the variables that are present, not only in our home shop environments, but in how we each envision the "right way" to create the blade/knife we are working on. Knifemaking/Bladesmithing is NOT a one size fits all type of thing..... and that's where the time and experience comes in. If you're not learning with each blade/knife you produce, then you've already missed the boat. Even after 30+ years of Bladesmithing, I still learn something new, each and every time I go to work in the shop. For me, always seeking improvement, and learning those "new" things, is what has kept my deep interest and adoration for this craft.
 
Thanks, guys. Just got home from work. (my wood carving class at the Vo-Tech) I sold 4 of the 6 carving knives I made. All of the people who bought them are experienced carvers and will be back for the Fall class. I'll ask for feedback, as they all know what to look for in a good carving knife. Based on my experience, they are good solid knives.........................but we'll see. They'll have 5 months to critique them.

I'd give anything if I'd had some "over his shoulder" time with my Uncle when he was making carving knives to know what his types of steel, heating, quenching and tempering data was. But I'm on my own on this journey. I've a lot to learn and know it!!!!! Thanks for the feedback on my question.
 
I will reccommend “The New Edge of The Anvil” book to help your carving knife/chisel or tool making. Great book wonderfully illustrated. I have read many Blacksmithing books and it is at the top with “The Complete Bladesmith” for knife forging.
 
Thanks, Chris, I'll check out both of those titles. I've been in touch with Walter Sorrells and sent him an e-mail earlier this afternoon. Will see what he suggests.
 
John Wilson said:
Another thing, Chris. You refer to 1084 as a beginner steel. Don’t fall into that trap. Of all the things that make a good knife, the type of steel is waaaayyy down the list.
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John, I think the reason 1084 is often referred to as "beginner steel" isn't anything to do with how good a blade it will make, but that it can be "fairly" successful HT'd with a forge and magnet. When planning to HT with a forge the type of steel is right up at the top.

Comments from other folks?
 
KenH said:
John, I think the reason 1084 is often referred to as "beginner steel" isn't anything to do with how good a blade it will make, but that it can be "fairly" successful HT'd with a forge and magnet. When planning to HT with a forge the type of steel is right up at the top.

Comments from other folks?
Click to expand...

Good point, Ken. I don’t use a lot of carbon steel but I always keep 1084 around. It is very good stuff.
 
KenK, I only referred to 1084 as a "beginners" tool steel because that's the term I've heard. I understand that reference is based on how easy it is to HT using a magnet as temperature guide. At this point, I'm forced to HT with a torch. That's not a big problem because the blades I'm presently working with are incredibly small since they are for carving knives.
 
Chris, you're not the only person to refer to 1084 as "beginner's" steel, it's pretty common phrase when referring to 1084 because it is so easy to HT without special equip.
 
Yup, Ken, that was what I was trying to say.

Would 1084 be a good steel to use for making carving knives? Walter Sorrells suggesteed O1, which is what I made this last batch of knives out of.
 
Walter answered my e-mail about recommended books. In a nutshell, this is what he said: Most of the books he read and re-read when he was first getting into blade making have long since gone out of print. But the authors have written other, newer books. He recommended three authors, Jim Hrisoulas (I guess "The Complete Bladesmith") Wayne Goddard and Ed Fowler. He also recommended "Steel Metallurgy for the Non-Metallurgist" by J.D. Verhoeven. His comment about it was "It's pretty advanced but worth reading and re-reading over time as you get more experienced. The hardcover book is crazy expensive, but there's a pdf available online that's authorized by Verhoeven, so you're not taking money out of his pocket by reading it." All of which was very helpful coming from a Master Bladesmith.

I really appreciate it when people of such stature in a field are so willing to help new people just finding an interest. I have found it to be that way in many fields of my interest and can't thank them enough.
 
Yes, there is a pdf out there that is pretty much the same thing as Steel Metallurgy for the Non-Metallurgist. However the book does not belong to John Verhoeven; it belongs to ASM International which you do take money from when you violate their copyright when you download that pdf. It also does take money out of John Verhoeven's pocket because ASM International pays him royalties on book sales.

Of the above authors I would say Jim Hrisoulas and John Verhoeven are the best. Wayne Goddard is good on the basics. However, and I hope I don't start a pi$$ing contest here, I do not recommend anything by Ed Fowler unless you want read some thoroughly entertaining stories.

Doug
 
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