I think we put WAY too much emphasis on alloys...

[kgd]

Interesting discussion. Personally, I have always been curious why folks who buy/collect folders tend to be more concerned with steel compared to fixed blades. Yes, I recognize that fix blades can be had in many steel types as well, but it seems that neither the variety of steel types nor the same kind of marketing angle typically goes into fixed blades.

Personally, I have noticed differences in edge performance that were greater between knives of the same steel type than across steel types. I've always attributed it to the heat treat.

 

[Ankerson]

Here is the last video in this series.

I will do more later, but they will be different.

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[Macchina]

I'll give the OP a fair hearing when he backs up his statements with good testing and provides us with the data. Until then, to me, he's just another "took a class, now I know everything". Seen too many of those, and I've done too much of my own testing to buy into it. You make me identical knives out of AUS 8 and D2, and I can tell you very quickly which is which.

So can a lot of other guys on this forum.

Seems like a whole lot of people like to attack me for "taking classes" for some reason. Please remember that the scientists and "experts" who you are defending leaned the same things about metallurgy that I am by "taking classes". What do you expect me to do when I want to learn about metallurgy and engineering? Go mine my own iron ore, build a smelting tower, and start from scratch? I'm all about second guessing what some guy says on the internet, but please don't say I know nothing BECAUSE I am trying to educate myself and earn my engineering degree!

True, I don't know close to everything there is to know about steel. I don't claim to though. I know all about what I am writing about though and I everyone who says I just took a class and now I know it all seems to be lacking on counter-points to what I am saying. As far as powdered metals go, I am out of my league there and overstepped myself there. Although alloys do diffuse with time in the austenitic phase, I don't think any heat treaters let thier steel soak for long enough to allow the alloys to properly diffuse into the steel matrix. Powdered metals do have the benefit of alloy a simpler heat treat and the end consumer may notice the difference because the PM steel was allowed to be heat treated properly.

I don't understand the person attacks in this case. Are you trying to make my point void by discrediting me? DID YOU READ WHAT I WROTE??? All that I wrote can be backed up by the science you think I am refuting! Do your own research about what heat treat does to the crystalline structure of steel. Please read about what effects vanadium, chromium, and molybdenum have on the structure of steel. What you'll find is that most all alloys either prevent corrosion (I don't at all refute this awesome property) or prevent grain growth. My point being that alloys do add a lot of control into the heat treat, but in themselves they don't add that much to the steel that the end consumer will see.

Please note that I am not saying that alloys don't do anything to the strength or edge holding ability of a blade, because they do add something. What I am saying is that hardness is the key factor in edge holding, yet I see way more emphasis put on what alloys a steel has instead of what hardness the steel is at and how it was brought to that hardness.

Do you know why INFI is so much stronger than other steels. I hate to burst the bubble, but it's mostly heat treat. INFI is not the hardest steel around, and that is what makes it so great. When you look and your specific use of a steel and are able to find just the right balance between hardness and ductility, you arrive at a the happy medium that INFI has found with its users.

Do you know why 440C can only achieve a maximum hardness of about 60 Rc even though it has as much or more carbon in it as 1095 (which can achieve 66 Rc)? It's because the chromium absorbs some of the carbon to form chromium carbides and not enough carbon is left to completely fill the structure with the iron. When 440C is quenched, not all of the structure is able to convert to martensite. Guess why 440C does not hold an edge as long as high hardness 1095 even though it's packed with chromium carbides and has as much carbon in it... did somebody say hardness?

Not one person has refuted the main point of my first post: Knife blade steel used to be hardened to about 55 Rc, now we are seeing the super steels hardened to 66 Rc. Does the correlation of hardness to edge holding not make sense to anybody else???

 

[Josh K]

^ I don't quite understand what you're saying. You're still not generating any hard numbers for us to look at.

 

[Macchina]

^ I don't quite understand what you're saying. You're still not generating any hard numbers for us to look at.

My point is not hard numbers. My point is steel used to be kept soft, now it's made ultra hard. The alloys help us get there, but people are too focused on the alloy content without realizing that it is the end result (hardness) that is actually driving edge holding.

Let me give you an example: What if Benchmade found out that when you take 304 stainless and add a peanut butter and jelly sandwich to it, you get an ultra hard, ultra strong, amazing blade steel called 304PB&J. Do you think people would be concerned the fact that there is PB&J in their steel? Do you think people would argue about weather or not grape jelly was better than strawberry jelly? What if Spyderco put a ham sandwich in with 440A (like Busse does with INFI) and they got a steel that was able to hold an edge 5% better just because they hardened it 1 Rc harder. Do you think people would compare the PB&J vs. Ham sandwich or would they compare the extra Rc.

My hard data is the Rc numbers you see in older steels (lower edge holding) vs. the higher Rc numbers you see in newer steels (higher edge holding). The alloys may have helped us get there, but people need to pay less attention to the ingredients of the apple pie and focus more on the fact that when made and baked correctly: all apple pie is awesome!

Hard numbers (no pun intended): S90V @ 55 Rc is not going to hold an edge as long as S90V 62 Rc. I don't have the graphs or charts or even data to show this. This is simple metallurgy and common sense. Ingredients (alloys) are the same, hardness is not the same.

 

[Gadgetaholic]

Seems like a whole lot of people like to attack me for "taking classes" for some reason.

I think you may have missed some classes on reading comprehension - "took a class, now I know everything" is NOT a criticism of you for 'taking classes'. The person that said that was criticising you for thinking you 'know everything' after having taken a class. This is kinda like the "hire a student straight out of university while they still know everything" idea. Sometimes someone that has taken classes then been out in the real world looking at the practical side of things realises that the classes didn't quite teach them 'everything'.

Until someone does some serious testing of identical knives with the same RC numbers but with different steels then it is hard to be sure of exactly how much difference the 'super steels' make. That testing should be for more than edge retention too - it should include tests of toughness. If a super steel retains an edge 2% better than a more mundane steel when both are hardened to RC 64, but the super steel is much less brittle and the edge chips less then the 'super steel' is quite a bit better than the 2% edge retention would suggest. Without the results of this testing I reserve my judgement on whether the steel makes a big difference or not.

I do agree though that the design & heat treat are each more important than the steel.

 

[bubblewhip]

My point is not hard numbers. My point is steel used to be kept soft, now it's made ultra hard. The alloys help us get there, but people are too focused on the alloy content without realizing that it is the end result (hardness) that is actually driving edge holding.

Let me give you an example: What if Benchmade found out that when you take 304 stainless and add a peanut butter and jelly sandwich to it, you get an ultra hard, ultra strong, amazing blade steel called 304PB&J. Do you think people would be concerned the fact that there is PB&J in their steel? Do you think people would argue about weather or not grape jelly was better than strawberry jelly? What if Spyderco put a ham sandwich in with 440A (like Busse does with INFI) and they got a steel that was able to hold an edge 5% better just because they hardened it 1 Rc harder. Do you think people would compare the PB&J vs. Ham sandwich or would they compare the extra Rc.

My hard data is the Rc numbers you see in older steels (lower edge holding) vs. the higher Rc numbers you see in newer steels (higher edge holding). The alloys may have helped us get there, but people need to pay less attention to the ingredients of the apple pie and focus more on the fact that when made and baked correctly: all apple pie is awesome!

Hard numbers (no pun intended): S90V @ 55 Rc is not going to hold an edge as long as S90V 62 Rc. I don't have the graphs or charts or even data to show this. This is simple metallurgy and common sense. Ingredients (alloys) are the same, hardness is not the same.

That makes no sense because if hardness was the only governing factor in edge retention, stainless blades would have the greatest edge retention against non stainless blades because Chromium gives a greater hardening factor to knives. Which may seem true for casual knife enthusiast which are only buying CPM S30V and VG-10, but the actual super steels like CPM 9V CPM M4 and 3V beat high chromium steels in edge retention. If that was also the case it would be impossible to make a knife both tough and have good edge retention. But steels like M4 and 3V give you close to S30V and D2 levels of edge retention with greater toughness the only sacrifice is stainless characteristics. HRC only works for that given steel it does not transfer to other steels because it will give off different characteristics. 440A treated to 55 is not the same as S30V treated to 55. You can't linearly say that HRC is transferable to all steels.

 

[pwet]

My point is not hard numbers. My point is steel used to be kept soft, now it's made ultra hard. The alloys help us get there, but people are too focused on the alloy content without realizing that it is the end result (hardness) that is actually driving edge holding.

Let me give you an example: What if Benchmade found out that when you take 304 stainless and add a peanut butter and jelly sandwich to it, you get an ultra hard, ultra strong, amazing blade steel called 304PB&J. Do you think people would be concerned the fact that there is PB&J in their steel? Do you think people would argue about weather or not grape jelly was better than strawberry jelly? What if Spyderco put a ham sandwich in with 440A (like Busse does with INFI) and they got a steel that was able to hold an edge 5% better just because they hardened it 1 Rc harder. Do you think people would compare the PB&J vs. Ham sandwich or would they compare the extra Rc.

My hard data is the Rc numbers you see in older steels (lower edge holding) vs. the higher Rc numbers you see in newer steels (higher edge holding). The alloys may have helped us get there, but people need to pay less attention to the ingredients of the apple pie and focus more on the fact that when made and baked correctly: all apple pie is awesome!

Hard numbers (no pun intended): S90V @ 55 Rc is not going to hold an edge as long as S90V 62 Rc. I don't have the graphs or charts or even data to show this. This is simple metallurgy and common sense. Ingredients (alloys) are the same, hardness is not the same.

basicaly you say that alloying is just a way to get higher HRC and higher hrc is what makes better edge retention ?

sorry if i missed your point but if i didnt it's just plain false. sorry.

s90v at 58 will outperform any simple carbon steel (iron+carbon) at 66 in edge retention. any day. steel composition with things such as vanadium carbides, chromium carbides etc has way more to do than HRC. shirogami 1 @ 66 is very hard but lacks wear resistance.

and no alloying is not what allowed harder blades, japanese made 66hrc blades out of shirogami 1 (1,4 carbon and almost no other alloying elements) even before you knew what a carbide was. and some very few high grade exemple apart alloying is not good for high hardness (ever seen S30v @ 66 ? plain carbon ca go that high way more easily )


and what makes most manufacter tend to pass the 60hrc bar is just customer demand, not new alloys.

 

[Macchina]

I think you may have missed some classes on reading comprehension - "took a class, now I know everything" is NOT a criticism of you for 'taking classes'. The person that said that was criticising you for thinking you 'know everything' after having taken a class. This is kinda like the "hire a student straight out of university while they still know everything" idea. Sometimes someone that has taken classes then been out in the real world looking at the practical side of things realises that the classes didn't quite teach them 'everything'.

In the very first sentence of my first post I said that I have been designing and building machines for 8 years. I am one of the primary purchasers of metals at my shop and also have a lot to do with choosing heat treat, target hardness, and calculating life of treated steels. I don't pretend to know everything, but I do know that I have experience in this field and I do know that I know what I am talking about when it comes to basic metallurgy.

Even if I am a college brat, what does that have to do with the fact that the new super steels are harder than older steels and also hold a better edge. I am simply out a correlation that anyone can see yet so many people seem to not want to see.

 

[me2]

You're getting replies like Sodak's because some of the stuff in your original post is not correct, incomplete, over-generalized, or misworded. Which of these you'll have to partly sort out yourself.

Also, some of your detractors agree with you that we put too much emphasis on alloy and leave out the other legs of the stand, like geometry, heat treatment, and intended use.

There are more reasons that just 2 for adding alloying elements. Wear resistance is a major reason for a lot of the newer steels used for knives, and it is heavily influence by alloy content. Maybe I should say its potential is influenced by alloy content, since heat treatment plays such a big role. Wear resistance can play a large part in edgeholding, though hardness is IMHO the major factor. However, once sufficient hardness is achieved, wear resistance becomes more important, as in 2 steels at the same relatively high hardness with different wear resistance. There is also the personal issue with knives. I prefer very high sharpness and my favorite steels will keep that for a while. This favors high hardness, typically 60 or greater. Many people will deal with a working edge that can still cut but can no longer shave hair or do fine cutting. For them, wear resistance is very important.
For someone like this, wear resistance in a steel like D2, CPM SxxV, and others, really will make a huge difference.

I still think you're missing the point by saying the steel industry is claiming some steels are vastly better. We are past the point that huge leaps in performance are easily found. They still do happen though. However, if you have a steel with 5% better wear resistance or 10% better toughness at the same hardness as it's competitors, I'd lump that in the "vastly superior" column. Industry will rant and rave for certain applications if they get 1% to 2% better performance. I happen to think a steel that wears slower than the grinding wheel used to shape it is pretty cool and vastly superior to previous steels in the wear department.

All that said, I still agree that knives function very well with fairly standard alloys given proper, and even superior, heat treatment. When you factor in cost, I really prefer the lower alloy steels for knives. I just have very few of them. 1095 is ok, O1 is better, S30V is slightly better. Its just like everything else, past a certain point, that little bit of extra performance really starts to cost you a lot. Some people are willing to pay for it, and the steel companies are not sinister or misleading for being willing to offer it. There are also some members here that purchased supersteels, and found the increase is not worth the price for them, so they don't buy any more. Some can't wait for 5% more and will snag it as soon as they can.

 

[singularity35]

Dude, not all apple pies are equally awesome. OK, so now I'd like to know something. Assuming the same blade geometry and equally excellent heat treat, can 1095 at 65 Rc perform as well as ZDP-189 at 65 RC as well? which metal performs better under those conditions? Or S90v and ZDP, for that matter, under the same set of circumstances?

 

[Macchina]

basicaly you say that alloying is just a way to get higher HRC and higher hrc is what makes better edge retention ?

sorry if i missed your point but if i didnt it's just plain false. sorry.

I am saying that alloys allow higher hardness without cracks. Alloys slow the growth of the steel grains therefor allowing a longer grace period between the austenic phase and the quech (slower cooling prevents cracks). Alloys have nothing to do with end hardness, that is bases solely on the amount of carbon that can enter the steel matrix.

Are you saying that higher hardness does not equal higher edge retention?

s90v at 58 will outperform any simple carbon steel (iron+carbon) at 62. any day. steel composition with things such as vanadium carbides, chromium carbides etc has way more to do than HRC.

I don't know if this test has ever been done in a controlled and scientific fashion, but I'd be interested to see the results if you can find any. From what I have learned, carbides in steel are made up of extra alloy material bonding with extra carbon. The carbides are like pepper in mashed potatoes and in the industrial world they are considered bad because they can cause high stress points in the matrix. I feel that there are too feel carbides to count on enough of them landing on the extreme edge to make a difference, but if you find those results, please post them.

and no alloying is not what allowed harder blades, japanese made 66hrc blades out of shirogami 1 (1,4 carbon and almost no other alloying elements) even before you knew what a carbide was. and some very few high grade exemple apart alloying is not good for high hardness (ever seen S30v @ 66 ? plain carbon ca go that high way more easily )


and what makes most manufacter tend to pass the 60hrc bar is just customer demand, not new alloys.

Wow, you've just completely backed up what I've been saying. Thanks!

 

[me2]

I'm not sure who you're asking, but since I'm being a knowitall today, I'll answer. What and how are you cutting? If cardboard, then zdp is my prediction. If heavy plastic zip ties, I'd bet 1095, but it depends on if either would chip. I'm betting ZDP would chip first, but I've been wrong before. Is there any side loading involved? How about light chopping? If so, 1095, but I must confess no experience with zdp in that area. My former Marine buddy chopped 5/8" plywood with a 1095 blade he hardened then tested to 66 HRc. No chipping.

 

[Macchina]

That makes no sense because if hardness was the only governing factor in edge retention, stainless blades would have the greatest edge retention against non stainless blades because Chromium gives a greater hardening factor to knives. Which may seem true for casual knife enthusiast which are only buying CPM S30V and VG-10, but the actual super steels like CPM 9V CPM M4 and 3V beat high chromium steels in edge retention. If that was also the case it would be impossible to make a knife both tough and have good edge retention. But steels like M4 and 3V give you close to S30V and D2 levels of edge retention with greater toughness the only sacrifice is stainless characteristics. HRC only works for that given steel it does not transfer to other steels because it will give off different characteristics. 440A treated to 55 is not the same as S30V treated to 55. You can't linearly say that HRC is transferable to all steels.

What?
CPM9V, CPMM4, and 3V are all alloyed steel. Stainless steel and Alloy steel do not mean the same thing. Stainless steel means it resist corrosion, alloy steel means the steel contains alloys (as do tool steels, stainless steels, and most powdered metals)

The Rockwell hardness rating is a STANDARDIZED test. S30V and 440A at 55 Rc are the exact same hardness. I think you mean to say that their are other characteristics that should be taken into account besides hardness alone. I agree, and to some extent alloys do add something to a steel besides attainable hardness. My point is that those alloys don't add as much as simple good heat treat and actual hardness do.

 

[Macchina]

Dude, not all apple pies are equally awesome. OK, so now I'd like to know something. Assuming the same blade geometry and equally excellent heat treat, can 1095 at 65 Rc perform as well as ZDP-189 at 65 RC as well? which metal performs better under those conditions? Or S90v and ZDP, for that matter, under the same set of circumstances?

Simple answer is no. I do not believe that a blade made of 1095 can be quenched fast enough to obtain 65 Rc and not have micro cracks (I may be wrong), so if we are comparing overall "usefulness" of the blade then the answer is no. I do know that 1095 at 65 Rc will be brittle, but I don't know how brittle ZDP-189 at 65 Rc is and how the two compare at that hardness. ZDP-189 is great stuff, and it exemplifies my point of not carring about alloy content, just looking at the hardness. Alloys allow ZDP-189 to get that hard without cracking, but I think a successfully hardened 1095 blade would compare quite well at 65 Rc when comparing edge holding abilities.

 

[Gator97]

I do not believe that a blade made of 1095 can be quenched fast enough to obtain 65 Rc and not have micro cracks (I may be wrong)

If I am not mistaken, Alvin Johnston and one more gentleman were hardening 1095 to 65HRC for light cutters.

I don't know how brittle ZDP-189 at 65 Rc is and how the two compare at that hardness.

Obviously depends on the application, but yesterday I've tested 2 ZDP-189 knives, at 63-64(Kershaw) and at 67HRC(William Henry) on 0.22mm thick Aluminum sheet, no chipping, at least not visible in microscope, micrographs and details here.

 

[Macchina]

If I am not mistaken, Alvin Johnston and one more gentleman were hardening 1095 to 65HRC for light cutters.

Awesome! I'd love to be there to see him do that, it amazes me what some people are capable of. I'd much rather have a 1095 65Rc blade than a ZDP-189 65Rc blade just because of what it means to have 1095 so close to the limit...

 

[hardheart]

Why use 1095? That's too much carbon to reach maximum hardness. You want cementite or something? Carbides are bad! I did not know that was such a blanket statement, I thought that if thy stayed out of the grain boundaries they were A-OK.

And if hardness is so important, then why is steel tempered after quenching? Hmm. Now why might alloying actually be a good thing?

Why just Rockwell testing? How about Knoop or Vickers? Does maybe Charpy/Izod impact testing have some value? Does it matter that 3V has more toughness and wear resistance than L6, D2, 52100, etc. at the same Rockwell hardness range? Is alloying at all relevant?

 

[sodak]

I am half way through a fairly advanced Metals Selection course and a lot of what we deal with is the molecular makeup of steels. I am finding out that a lot of what knife/steel companies tell us is total bullcrap.

And you wonder why you aren't being taken seriously. Read your own last sentence again.

As far as most of the industry is concerned, 99% of alloys are added to steel for two things: corrosion resistance or depth of hardness.

Really. Alloys can add many desirable qualities to the steel, and many times, they act in tandem.

For the most part, it's good old carbon and heat treat that does almost EVERYTHING for the edge, good or bad.

The big 3 for a good edge are steel type, heat treat, and geometry. All are important, not just heat treat. Geometry cuts. Steel type and heat treat allow the knife maker to optimize the geometry.

Steel companies put out a lot of literature that makes it seem like the newest steels are vastly better, but for the most part I think it's in our heads.

Some of the newest steels ARE vastly better. For hunting knives, I've yet to find anything that can compare to CPM 10V, properly heat treated and ground.

It took me a lot of science to realize that steels aren't really getting much better, the heat treat and metallurgy are simply getting more precise and allowing us to achieve higher hardness.

Heat treat and metallurgy are getting more precise, AND steels are getting better. We're getting more out of the "old" steels, and raising the bar with newer steels.

Now we are seeing super steals up to 66 Rc (ZDP-189, M2, etc.) but these knives are usually quite brittle and suffer from edge chipping whenever they encounter resistance.

I've yet to see any of my ZDP knives chip, except for one instance of gross abuse on my part. This was on an edge that mic'd out to less than 0.005 of an inch. The amount of force to cause the chip was substantial. So give me some example of brittleness of ZDP and M2. M2 HSS hardened to 66 HRC is used in power hacksaw blades. I have quite a few left, some of which I've sent to fellow forumites to make knives out of. Very good edge holding, very, very tough.

Ever see a power hacksaw in action? Yet you claim that M2 at 66 is brittle? Sounds like total bullcrap to me (to use your words).

That's odd: Hardness = edge retention (who wudda thunk it)

We've been talking about this for over 10 years on this forum. Alvin Johnston and Cliff Stamp were discussing this on rec.knives before that. When edge degradation is caused by deformation, then increased hardness does indeed give superior performance. The harder the knife, the stronger the steel.

When edge degradation is caused by other things, then other factors come into play. This is not a new topic that you have discovered.

There. I've been reading your posts. Heat treat is important, but it has to be balanced with other factors - geometry and steel type are 2, but there are other desired characteristics that need to be thought of. To cast aspersions on an entire industry is immature and uncalled for. There is hype in the industry, and there is also a TON of highly reputable professionals who have forgotten more about steel than you and I put together will probably ever know.

There are other members of this forum who are REAL metallurgists with degrees and advanced degrees on the subject, as well as years of experience. Many people here (myself included) have engineering degrees. I suggest you tread lightly and try reading and searching old posts. You might learn some things.

 

[Macchina]

And you wonder why you aren't being taken seriously. Read your own last sentence again.

Read it again and I still feel like advertising is advertising whether it be from Crucible Metals or the latest diet fad.

Really. Alloys can add many desirable qualities to the steel, and many times, they act in tandem.

When you combine steel construction, automotive and transportation, consumables, general steel structures, etc. I think you'll realize just how much steel is unalloyed all together, and the steel that is alloyed is simply alloyed to allow for a deeper heat treat with less risk of cracking. Alloy steel is very expensive and in industrial applications people do everything they can to stick to simple carbon steel.

The big 3 for a good edge are steel type, heat treat, and geometry. All are important, not just heat treat. Geometry cuts. Steel type and heat treat allow the knife maker to optimize the geometry.

Sorry, I meant between alloys and carbon content (as related to hardness), hardness contributes to edge holding a whole lot more than alloys. you can add as much vanadium to mild steel as you want, and you won't get a good knife blade without that carbon...

Some of the newest steels ARE vastly better. For hunting knives, I've yet to find anything that can compare to CPM 10V, properly heat treated and ground.

I cannot even begin to argue with your personal experience. You stated above, heat treat and edge geometry are equally important in rating a knife. Do you have the exact same knife in CPM 10V as you do in older steels? Same heat treat? Same edge geometry?

Heat treat and metallurgy are getting more precise, AND steels are getting better. We're getting more out of the "old" steels, and raising the bar with newer steels.

Yes, this is my point. Knives are getting harder: edges are lasting longer.

I've yet to see any of my ZDP knives chip, except for one instance of gross abuse on my part. This was on an edge that mic'd out to less than 0.005 of an inch. The amount of force to cause the chip was substantial. So give me some example of brittleness of ZDP and M2. M2 HSS hardened to 66 HRC is used in power hacksaw blades. I have quite a few left, some of which I've sent to fellow forumites to make knives out of. Very good edge holding, very, very tough.


Ever see a power hacksaw in action? Yet you claim that M2 at 66 is brittle? Sounds like total bullcrap to me (to use your words).

Nope, I claim that when steels get hard they get MORE brittle. It's the way things work. Every steel has a balance of hardness and ductility, when one goes up, the other goes down: it's as simple as that. This is not to say that a hardened steel cannot take incredible loading before breaking. Also, I don't think hacksaw blades are run at 66 Rc... That means they would have to be quenched at the absolute maximum hardness and not tempered a bit. Please find a manufacturer that is selling 66 Rc hacksaw blades...

As far as the ZDP-189 goes, I cannot argue with your personal experience. All I can tell from your statement is that you own a ZDP-189 blade that chipped

We've been talking about this for over 10 years on this forum. Alvin Johnston and Cliff Stamp were discussing this on rec.knives before that. When edge degradation is caused by deformation, then increased hardness does indeed give superior performance. The harder the knife, the stronger the steel.

Not exatly true. The harder the knife, the more resistant to deformation. A harder edge will break before it deforms because it's ductility has been reduced. If "The harder the knife, the stronger the steel" were true then we wouldn't temper anything and all blades would be made of high carbon steel with 66 Rc ratings.

When edge degradation is caused by other things, then other factors come into play. This is not a new topic that you have discovered.

There. I've been reading your posts. Heat treat is important, but it has to be balanced with other factors - geometry and steel type are 2, but there are other desired characteristics that need to be thought of. To cast aspersions on an entire industry is immature and uncalled for. There is hype in the industry, and there is also a TON of highly reputable professionals who have forgotten more about steel than you and I put together will probably ever know.

There are other members of this forum who are REAL metallurgists with degrees and advanced degrees on the subject, as well as years of experience. Many people here (myself included) have engineering degrees. I suggest you tread lightly and try reading and searching old posts. You might learn some things.

Sorry my opinion offended you, but everyone has the same right to a discussion no matter level of education or occupation. Do you disagree with my statement that old steels are soft and new steels are hard? Do you disagree with my statement that alloys don't matter as much to the end consumer as hardness and heat treat do? I am not trying to cast aspersions on the steel industry as much as I am trying to get people to stop focusing on the alloys within the steel instead of where the steel arrived after heat treat. Knife companies have preyed on this hype by over-advertising steel type because of the belief that heat treat doesn't matter as much as alloy content. Gerber is a great example of this with S30V that performs very poorly due to improper heat treat.

I'm about to lock this thread because it has taken a horrible turn away from what I intended. Sure I don't everything, I don't think I know that much at all in big picture of things. But I do know enough to see that alloys are used to get steel to do what you want in heat treat, but they have taken on a whole life of their own here on Bladeforums. People nit-pick over tiny percentage changes between two steels without even discussing the hardness of the steels in question. My intention of this thread was to use the science of steels that I know to show that alloys are generally used to get the steel to do what you want during the heat treat process and not to add these miraculous abilities to steels that some people think they do. Instead, this thread has turned into people attacking me, my education, and my knowledge.

I know I made a few mistakes, I know I don't know nearly everything there is to know about steel, but does that really prevent me from making the statement that hardness is the primary factor in edge holding?