heat treating hype and reality

Stacy E. Apelt - Bladesmith

Stacy E. Apelt - Bladesmith

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In a series of emails to several newer makers I have come to believe that many are reading more into the numbers than is really necessary. Here is one of my replies to get this subject going.

There is a big thing being made by a lot of makers, "Oh, my blades are all Rc 61.etc..."( I have heard boasts of Rc66). This is mostly said by those who don't understand the actual situation. An example is a piece of glass. It has a high Rc but makes a poor knife. It will get razor sharp (sharper than any steel blade is able to) but the edge will chip and the blade will break. A plain piece of unhardened steel can be honed to a very sharp edge,and will not break under most any use. It just won't be able to keep that edge from wearing away or bending over.This too would be a poor knife.The optimal knife is one that has some features of both.
The aim of making a quality knife blade is to have a hardened edge that can withstand use (and a bit of abuse), be easily sharpened, and be tough.Its edge should be tough enough not to chip out or roll over. The Rc figures found on most charts are for industrially quenched large objects and tools, not knives. A good blade will temper down to Rc 59 area, and be springy enough to withstand side pressure without bending permanently or breaking.This is the subject that Ed Fowler,mete, Kevin and others like myself discuss ( I do not put myself in their sphere of expertise). Few ABS master smith blades are hardened beyond a final Rc 59. I can assure you no Rc61 blade ever passed the JS or MS testing.
The idea is to get a particular steel and learn all you can about how it works for YOU. If you have a lab with a SEM and argon shielded ovens - that is what you should master. If it is a propane torch, a can of ATF, and a set of yard sale files - that is what you should master.
I do O-1 blades with the Ac temps for O-1 ,a quench in Heat Bath's AAA and a double temper at 400, and a spine draw to achieve a properly balanced blade of a hard edge and a soft spine. On a blade done this way the Rc will vary depending on where you test.Rc 52 on some places, Rc59 at the very edge. A blade like this will outperform almost any simple quench and temper blade.

So to make it a simple catch phrase, "Don't learn the numbers...learn what the numbers represent."

I would rather have a blade made by a smith who understood the theory of knifemaking and made his blades to do a specific purpose (with procedures designed to attain that purpose) and didn't really care what the Rc is ,than one from a person who said ,"The chart said Rc61 so I tempered for that target hardness."
Stacy
 
I know that this has been said before, but the JS and MS testing requirements are not meant to be what constitutes "the ideal knife". I am sure that under certain circumstances it would constitute "the less than ideal knife". It was explained to me once that the testing requirements (for flexing the blade) were set so that a smith could prove some kind of knowledge of the heat treating process and how it affects the overall performance characteristics. He who controls the heat, controls the steel. I've been doing some study and reading on my own and, I have to say it is easy to be misled or get confused by the jargon and numbers. I agree with Stacy, the numbers don't mean much if you don't know what is going on in the steel when the heat is applied. Just my $.02 worth. -Matt-
 
Testing is just like putting together a jigsaw puzzle in order to guess what the complete picture is. Rockwell, while a little more precise than some improvised methods used by smiths, is still just a single piece of the puzzle. It can tell you how hard the steel is but it can’t tell you anything about grain size (larger grains harden easier) or carbide distribution. What makes our job even tougher is that we have a pile of puzzle pieces to choose from with some not even belonging to the same picture. Many bladesmiths have a very hard time determining which pieces belong to their puzzle and the overall picture ends up looking like a Picasso painting that they interpret any way they feel like. And others like to tell you what you should see in their fragmented puzzle, example:

I have seen some yahoos use a conversion table to translate microhardness tests into HRC numbers and use it in very ethically challenged hype spewing. Folks need to be aware of this trick! Rockwell gives you a general hardness of the material as a whole, while microhardness tests can measure the hardness of a very precise microscopic area, such as individual carbides, which is much harder than steel could be expected to get. Some jokers will then use a table to convert those numbers to Rockwell and make the claim that their blades gave a reading of 66HRC+ and are still very tough or can even bend 90 degrees. This is a complete contradiction as Rockwell is the measure of deformation from the penetrator, deformation =ductility. Higher Rockwell numbers means less ductility, when somebody tells you they are bending (ductility again) a high Rockwell steel they are calling you an idiot that they think will believe the steel has some sort of magic switch allowing it to go selectively strong or ductile at will. :jerkit:

There are days that I just want to dispense with the diplomacy and call a spade a spade, but let’s just say that there are folks out there who intentionally mislead buyers and other makers in order to grab their part of the spotlight and rely upon the public’s lack of knowledge not to get caught. I don’t know why it bothers me more than most, but it pi$$#$ me off more every year, and is the reason you have to put up with my incessant soap box talks. But one reason I don’t let up is that they never do!:grumpy:
 
I enjoy going to knife shows. I like talking with other makers and exchanging

ideas. Some times I even enjoy the food, thow rarely.

What I enjoy most is having a knowledgable buyer at my table.

Someone who has a good overall understanding of knives and the steels

they are made from.

It makes for an enjoyable discourse, without the smoke and mirrors or the

debunking of the outlandish claims made and considered factual by some

makers and many buyers.

Fred
 
....you mean I DON'T pick up another 2 points Rockwell by using a magnetized anvil????
 
deker said:
You do, but only if it's pointed north and you're using a rooster, not a chicken... :D

-d
Click to expand...

You forgot the chant:D


Seriously though...I have some blades just out of HT to make 7 knives that I ground last week. They have all be tempered to what I've been told is their "optimum" Rockwell hardness for a blade made of A2 and D2.

When I get them finished and hand them over to their new owner, I'm going to tell them, "this is a knife, not a prybar".

That's my story and I'm stickin to it:)
 
Matt, you are correct that a JS/MS knife isn't the ideal knife. I should have elaborated in an aside.I did not mean to imply that they are in any way superior. The conversation I was referring to had references to such matters. The point is that just shooting for a certain Rc is not the way to go. Shoot for a given purpose (the ABS test knives have a given purpose) and make the knife perform that duty to the highest degree. A camp chopper will have a completely different HT than a sashimi knife.
Stacy

PS: Your 2cents has a $ worth of wisdom.
 
bladsmth said:
Matt, you are correct that a JS/MS knife isn't the ideal knife. I should have elaborated in an aside.I did not mean to imply that they are in any way superior. The conversation I was referring to had references to such matters. The point is that just shooting for a certain Rc is not the way to go. Shoot for a given purpose (the ABS test knives have a given purpose) and make the knife perform that duty to the highest degree. A camp chopper will have a completely different HT than a sashimi knife.
Stacy

PS: Your 2cents has a $ worth of wisdom.
Click to expand...

Stacy, I must have read the post too fast and missed the overall meaning, my apologies. Electronic media sucks as a form of effective communication IMHO, but that's all we have here. I agree with your posts 100%. The Rockwell point issue that you brought up is a good one. It's kind of like when a person reads steel usage charts backward. They see that "knife" is one of the many uses for the grade O-1 tool steel. The knives they are talking about are used for industry purposes that require much more hardness than our knives do. Many of the steels that we use for knives were made for industry ( I know, knives have to be made of something) and the heat treat specs and procedures are geared toward industrial use. They are the correct way to heat treat that steel, but we have to make some adjustments for the intended use for the knife. -Matt-
 
Man, I just want mine to cut....that's all.....lol.
 
grease-man said:
...It's kind of like when a person reads steel usage charts backward. They see that "knife" is one of the many uses for the grade O-1 tool steel... -Matt-
Click to expand...

I believe this is the source of problems like the plethora of posts regarding why a persons knife cut from a sawblade doesn't act like L6- well because it is not L6! Recycling old items into knifeblades is a cool and attractive idea so I am not beating that old equine skeleton here, but instead addressing your point Matt. Those charts are indeed not any sort of reliable indicator of what type of steel an item may be since, as you rightfully pointed out, that would be reading them entirely backwards. How one should use those tables is in determining what steel you want to buy, for your application, by looking at what they had in mind when developing the distinctive chemistry for that steel.

Any actual item can be made from any steel the manufacturer found most economical that week, and these days probably some cheaper soft alloy with special inserts or coatings only at the actual interface with the work, this could be true of a range from bearings to bandsaws. Folks could save themselves a lot of aggravation of they realize that those charts are much more usefull to folks who buy new steel than they are to those who wish to recycle.
 
It appears to me that a "steel usage chart for custom knives" would be a great benefit to all of us, especially us newbies! Has anyone thought of creating a chart of this type? Or is one already available?

I'm thinking each knife steel type could be broken down into types of knives, with a suggested heat treat process for each of those types. With a resulting Rc throughout the process. Such as Rc after hardening and tempering.

I for one, do not have the knowledge yet to create such a heat treat chart, but would be willing to begin one with the help of some of the more experienced in each steel type. I could begin by searching through the threads here to understand the processes used by many of us and begin creating a document. I would then look to our experts here to assist me in refining the chart (Cashen, Apelt, Fowler, etc.) Once completed, the chart could be posted here in a thread as an attachment that any knife maker could refer to, for the particular steel they want to utilize and the intended knife and use that the knife will see in real life. This will allow any of us to quickly send someone to, "a best in practices" type of chart, so that they have a starting point when beginning to use a "new" steel.

As I stated, I'm willing to gather all of the information and create a document for us. How many of you would like to contribute to this kind of a project?
 
scottickes said:
It appears to me that a "steel usage chart for custom knives" would be a great benefit to all of us, especially us newbies! Has anyone thought of creating a chart of this type? Or is one already available?

I'm thinking each knife steel type could be broken down into types of knives, with a suggested heat treat process for each of those types. With a resulting Rc throughout the process. Such as Rc after hardening and tempering.

I for one, do not have the knowledge yet to create such a heat treat chart, but would be willing to begin one with the help of some of the more experienced in each steel type. I could begin by searching through the threads here to understand the processes used by many of us and begin creating a document. I would then look to our experts here to assist me in refining the chart (Cashen, Apelt, Fowler, etc.) Once completed, the chart could be posted here in a thread as an attachment that any knife maker could refer to, for the particular steel they want to utilize and the intended knife and use that the knife will see in real life. This will allow any of us to quickly send someone to, "a best in practices" type of chart, so that they have a starting point when beginning to use a "new" steel.

As I stated, I'm willing to gather all of the information and create a document for us. How many of you would like to contribute to this kind of a project?
Click to expand...

Sounds like a one heck of a project! In theory it sounds like a great idea, but would it even be possible? Or practical, for that matter, given the tremendous amount of steels used and variations of the heat treat method used for each given steel? I'm by no means trying to be a "nay-sayer" here, maybe I'm thinking too far into it. If it can be done practically and realistically, I'm all for it! Kind of like a "steel recipe book". Now I'm kind of excited!
 
What percentage of forgers have beards and do they make better knives ??
 
mete said:
What percentage of forgers have beards and do they make better knives ??
Click to expand...

I don't know about beards, but maybe a good 'beer gut' would help by mellowing the resonance of the hammer blows-- making such blows more 'sympathetic' to the harmonic predisposition of steel atoms. :thumbup:

That and an XXL magnetic bracelet strapped around the horn of your anvil and you're all set!
 
Resonance of the blows ? They just tore down a bridge here .When they were undercutting the concrete of one of the supports they hit the resonant frequency of the truss.!! The whole truss vibrated, a shower of debris came off it and the sound was very obvious - a low frequency pulsing !!! The photo shows the truss just as it came down, the whole thing resonated just before !!
 

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