The BIGGEST LIE in the knife industry- Good Heat Treatment vs BAD Heat Treatment

[@OUTDOORS55]

Sorry one detail I forgot to mention was the steel is 1084. I knew I was forgetting something 😂

[@Butthead98]

you didnt, you actually mentioned it around 14:52, great vid tho!

[@PetesGuide]

Actually you did at exactly 14:00 and 14:55 even though you didn’t explicitly say earlier that’s what these knives were made from.

[@tacticalcenter8658]

1084(AISI) - Simple carbon steel, low wear resistance, decent shock resistance. Manufacturing Technology - Ingot Country - United States USA

[@brianlawson3757]

No, you mentioned it at the very end and my ears picked up on it. You just didn't have it on your comparison layout paper. It's the same steel I'm working in right now while I can get it. The 1080 series seems to be one of those blends that is only around here and there like D2, W1, and W2 were when I first started forging blades.

[@OUTDOORS55]

Ha! I meant to mention at the beginning..oh well glad its in there somewhere though 👍

[@cypher6083]

What I learned from this experiment is that even if you are a professional knife maker who does a month long experiment there will always be a 16 year old Redditor in the comments claiming to have a more informed opinion.

[@1wickedmonkey2]

ALWAYS! And they just can't seem to help themselves. I even had a guy tell me I was "using the wrong steel to make a straight razor and razors need to be made out of stainless" (I make razors out of 1095, W1, and W2) granted they then admitted they didn't know what W2 even was... I seriously wanted to slap someone through a computer screen. Just had to remind myself, their just an idiot... idiots happen... its part of the human condition.

[@LostLargeCats]

As a 16 year old redditor, I'm jealous of his forearm muscles.

[@cypher6083]

@@LostLargeCats Yea I've only got about 20 minutes of sanding/grinding/polishing in me before I'm done for the day. XD

[@charlesjonestherednecknerd]

Basically, this is what I have always heard. HRC goes to edge retention. Proper heat treatment (temperature and tempering) goes to the toughness of the blade and how well it can take impacts and lessens the chance of breaking or failing during usage. To me heat treatment is all important. So a 57 HRC might be my choice over a 62 HRC I can sharpen a knife with a pocket diamond stone or ceramic rod even in the field. What I can't do is replace one in the field that breaks.

[@christopherrowley7506]

Exactly! His statement: "When people talk about performance they are talking about edge retention" really frustrates me because it's too true, when it shouldn't be. People these days obsess over edge retention and they get overly brittle and impossible to sharpen knives.

[@baadtaste1337]

@@christopherrowley7506 Bought a chefs knife once that was so hard i could not sharpen it in a normal way. It ended up being used in the garden :D

[@mikeries8549]

​@@baadtaste1337 surgical steel

[@jic1]

@@mikeries8549 When a knife is sold as being made with 'surgical steel' without being any more specific, that almost invariably means that it's made of 420J2 stainless (or nearest Chinese or Japanese equivalent). 420J2 is about as soft as a steel can be and still make a useful knife. It's sold as 'surgical' because it's extremely corrosion resistant, and therefore ideal for surgical instruments. it's more likely that this 'unsharpenable' knife is made of what would be considered a 'tool steel'.

[@RelativelyBest]

Yeah, this has always been my understanding, since my interests lie more towards swords and other weapons as opposed to knives meant as tools. For a weapon, you'll often even prioritize durability over sharpness - a slightly dull sword is better than a broken one - so proper heat treatment is very important. It never occurred to me that for tool knives the priority might be reversed, but I guess that makes sense.

[@kelvinsullivan6299]

The answer to the quandary is obvious. The badly treated knives lacked handles and were therefore cold. Which meant they were shivering at the same frequency as an oscillating tool which caused them to appear artificially sharp

[@rrcaniglia]

Clever! Love it.

[@joshalmightyblades]

Uma...

[@BobJones-bh9qz]

The poor knives exposed out in the cold 😔

[@e.t.preppin7084]

Brilliant deduction, is your real name Watson by any chance 😂

[@uncletiggermclaren7592]

Poor-mans' vibro-dag.

[@jonduncansakurawallknifegarden]

Most thorough, most underrated, most professional “knife and steel reviewer” knife guy on the internet for actual testing. You and Larrin Thomas are doing God’s work. Thank you. Been watching for years and I go back to watch any that I missed.

[@jaysonfraser5268]

The trouble with heat treatment from a consumer perspective is that it’s hard to quantify. Someone can tell me that Spyderco (for example) does an excellent job with heat treatment, but someone like me doesn’t really know what that means. Hardness, on the other hand, can be tested with a fancy machine like yours and listed in the specs. I’m no metallurgist, but if I’m choosing between two knives I’m at least smart enough to know that 61 is higher than 58. Most people wouldn’t put the effort into understanding the intricacies of heat treatment even if companies presented it as plainly as possible. In other words, while heat treatment is likely just as important, hardness numbers still make more sense for layman knife shoppers.

[@OllieVK]

Bzzzt. White iron can be 65 Rockwell, but would be a rubbish blade. Relying on hardness alone is misguided. It's like only relying on the miles per gallon when buying a vehicle.

[@AlexanderMason1]

@@OllieVK exactly. Some steel at 58 HRC will be far superior to another steel at 63HRC for example. Also two steels with the same hardness will be entirely different in performance, toughness, edge retention etc. What matters is the specific steel being used as well as the heat treatment.

[@geico1975]

Well, I've always heard one of the best in the industry is Buck, the whole Boss Heat Treat thing, but I sent a 110 in under warranty because the tip broke off on me. Of course, I'm hoping I had a lemon and I'll never worry about that again. A month later another Buck 722 Spitfire I had broke, the internal mechanism snapped or something sent it in, haven't gotten them back yet, but totally rethinking Buck.

[@AlexanderMason1]

@@geico1975 probably something you did.

[@MatrixCoreteam]

As a metallurgist, if someone tells me that one is 58 and the other is 61 I would assume both could have come off the same load. We don't heat treat to a single hardness. We heat treat to a range. Even a hardness test block has +/-.5 HRc uncertainty.

[@ieatcaribou7852]

So glad to see you back on KZbin. Thanks for doing all of this frustrating work for all of us. You really do a great job of simplifying tests and explaining it to your audience.

[@joshingle8532]

This was extremely well done. Interesting to say the least. I’d love to see more vids like this bud

[@Enes-wj5xq]

Can you harden a knife by magnetizing it for along period of time ?

[@mountainholler290]

​@@Enes-wj5xq no .

[@norbertnagy5514]

​@@Enes-wj5xqi dont think so, but it probably becames magnetized itself.

[@andrewayers1141]

This is just based on my experience and own personal research but likely the reason why all three of the knives had similar edge retention is because in reality what you're testing is abrasion resistance which with a more basic carbon steel like the 1084 that you were testing with, it pretty much just comes down to the hardness (and edge geometry, which was identical) of it which all of them were nearly identical. Toughness, strength, and apex/edge stability are much more open to variation depending on the other specifics that come along with heat treatment, which is exactly what your testing showed. Honestly, these results didn't surprise me at all, the results reconfirmed prior conclusions I've made. That's why HRC is just one indicator for a good heat treatment and isn't the only way that a person should be evaluating purchasing a knife. Videos of real world testing actually demonstrating the edge retention, toughness, strength, and edge stability are the best resource.

[@MrSunrise-]

Yeppers. 1084 is a pretty simple steel. Going to A2 yields much greater abrasion resistance (edge holding) because of the wear-resistant complex carbides formed, but heat treating is a little trickier - you need to watch your austintizing temperature and temper to Rc58 to get a maximally tough blade. If you're going to put all of that work into a blade, use a good steel and have it properly heat treated.

[@barkingspider2007]

I tend to buy knives with higher claimed HRC. The chipping issue is something the OEM's tend to discount as ____________ steel is difficult to work with and prone to chipping. Maxamet knives are a good example. I purchased two identical knives, one chipped like mad, the other ZERO issues. I sent the chipping knife back to the OEM and was told the Rockwell was "within spec" good luck with the knife... The chipping issue eventually sharpened out. The knife still has damage where the chips were too deep to completely remove. (waste of knife steel, only cosmetic issue.) Thanks for the video, excellent work! : )

[@Incandescentiron]

Great experiment. So, Edge retention and toughness are somewhat independent of each other. That is very valuable information. Thank you for posting!

[@OUTDOORS55]

Yes exactly👍👍 two different things 🙂

[@NandoKleijn]

Man, you seriously know science, especially after including the exceptions and disclaimers. I love your approach on steels and their properties, and your channel of course.

[@GreenBeetle]

Great video! It would be interesting to compare toughness of a well heat treated knife at 61 HRC with poorly heat treated knife at 58 HRC.

[@rrcaniglia]

Or vice versa.

[@me2bfc]

Unfortunately the relationship between toughness and hardness is not linear and quite steel specific. The poorly treated knife at 58 could be notably less tough than one at 61 with a good treatment.

[@oldeays5085]

58 HRC is not poorly heat treatment at all!! 😂

[@me2bfc]

@@oldeays5085 depends on how it got there. Pull out of the fire/oven and quench and you can get to 58 without even tempering if you mismatch the steel and the quench.

[@adawolf9483]

Toughness will always be worse in the poorly heat treated knife regardless of the HRC.

[@joestahl5649]

Hey there, great video! I wanted to add a little thought to the discussion that you didnt mention in your video. I believe it is wrong to reduce the knives performance to edge retention of the blade where harder means better. By following through with that thought, the best knive would be a knive that has not been annealed at all. Your findings do prove that there is a difference in quality that is independent of the hardness value, after all nonne wants a kitchen knife to break upon cutting into a bone. Wich could happen with a knife that is equally bad as the third one. But on the other hand i do not believe that it is possible or sensible to try and find a metric to measure the quality of the heat treatment, since the manufacturers of quality knives have figuered it out anyways and the manufacturers of bad knives (i.e. the 26$ damacus knive you teste) lie about their products anyways. I believe the current system, where we get an information about the hardness and assume that it has been heat treated correctly, is flawed but there is no realistic benefit for the average consumer to change anything about it. Btw i love that you try to test things, that are currently measured by feelings and subjective means, in a way that is as scientific as humanly possible. Keep up the good work man!

[@Muscovy7]

Interesting results, toughness definitely matters for chipping on the edge. I imagine the results for edge stability in super steels would be interesting.

[@Skidgiz99]

Super glad you did this video. A few of my first knives were quenched way too hot and I've been really trying to get my heat treatment sorted

[@CagedSUPERMAN]

Shit I’ve had a string of good ones and really shitty ones. I don’t know what’s going on

[@LifeMyWay007]

I have Absolutely NO IDEA WHY, but You are one of my Most Favorite Channels!!! Keep up whatever Magic you do in your videos :)

[@VTPSTTU]

Thanks for an excellent video. An interesting test would be to take the knife with the poor heat treatment and re-treat that knife with the good heat treatment to see what effect you would get. The long and hot initial treatment would cause grain growth, but the quench might set up the microstructure to have a better grain size on a second heat treatment. The other possibility is that the prior austenite grain boundaries are already established as large grains and that you wouldn't fully recover the grain structure. Getting the steel back to where it should be might require annealing, rolling, and heat treating from the beginning. All of my classes in this area were too long ago for me to remember what the answer is.

[@clivegower-collins9012]

A thoughtful video with more evidence and detail than most. Keep feeding through useful stuff like this please. Appreciate your channel

[@DanieHattingh]

This was amazing. It confirmed a few suspicions I had too. Thank you so much for going through all this effort. It would've taken me years to get this amount of experience.

[@timcline2799]

Very impressive. So thorough. Full comprehension of theory while taking practical to maximum. The edge retention testing done here is supreme.

[@houseblacksmithing9836]

You did a good job! Hardness determines edge retention and abrasion resistance. But grain size determines toughness, in choppers, axes, and swords heat treatment is key to the performance of the blade. I have had poorly heat treated blades snap, much sooner than a properly heat treated blade.

[@thorwaldjohanson2526]

Another point is that you can get a thinner edge (more acute angle) with a tougher steel, without getting chipping. A thinner edge INCREASES edge retention. So the truly telling test would be to grind the 3 knives to an angle where they don't chip or roll on normal cutting tasks. Then see how the edge retention compares. (follow up video? *wink wink *)

[@brianlawson3757]

This was a great, down to the bones kind of video. I found it especially helpful since I'm currently using only 1084 and really trying to pin down how to get my best results with it. When I worked 1095 years ago out of an anthracite coal forge, all my blades failed because of grain growth. I just couldn't give it a steady soak without going too hot at some point and the grain looked like that moldable sand kids play with. Total disaster for me. I'm trying to focus now on maximizing durability. I'm getting ready to make a knife for my little nephew for when he goes out fishing or hunting with his dad, and if he's anything like I was as a boy, he'll need a blade that can hold up to um,...'rough' treatment 😉👍

[@daw162]

if you're heat treating in a forge, you'll need to heat the steel and not the forge. The advice to try to make a forge perform like a furnace is bad advice for simple stuff. If you can have a hot spot at your burner or burners and the ability to move the blade in and out of it, you'll get no grain growth with 1084 and 1095 if you do a low temperature pre-quench, then do thermal cycles - pull the blade out of the forge and let it cool to black each time and then heat only to nonmagnet plus a little bit of a temperature overshot as much as you can get one in literally 10 seconds and then quench. You should end up with finer grain than you'll see pictures of anywhere else and nothing unusual in the structure of the steel. if you use 1084 and overshoot temp once after the thermal cycles "just to be sure it's hot enough" for 15 seconds, the grain growth will double in size. 1095 is a little more forgiving, but it doesn't have any real margin to give in toughness. You can practice the thermal cycles by overshooting temperature on a sample for 15 seconds and examining it vs. something annealed once and quenched just after nonmagnetic. The latter will double in size grain wise. Take magnified pictures of the grain, then do thermal cycles with the large grain sample and bring it back to grain smaller than the part that you intentionally didn't overheat. That gives you a very good idea of what you're seeing in forge by looks and by time and how much it affects grain. You'll want to take an offcut and do this with everything you'd like to use. 80crV2, for example, suffers no visual change after a 15 second high temperature overshot. That doesn't mean the intentional overshot past just a little is a good idea, it just lets you know what you're dealing with.

[@beetroot7486]

If you want even heat in a solid fuel forge, place a thick walled (thin walled works too) pipe in the coals and bring it to temperature, then place the blade inside and the radiant heat will heat it up very evenly.

[@mikafoxx2717]

Watch larrin's video on heat treating with a forge. Just only to magnetic from a normalized blade. If it's not magnetic it's hot enough, no matter the temperature, if starting from normalized steel. You don't get a huge range of hardness value this way, though, so you have to choose the steel for the task. 52100 will be hard as hell but not tough enough for a sword where 5160 would be a better choice.

[@KnifeSteelNerds]

Very fun, practical testing to show the differences created from bad heat treating.

[@KillaZamii]

What’s poppin larrin

[@dan_taninecz_geopol]

Bah gawd that's Larrin's music!

[@donttreadonme1423]

Came looking for the Larrin stamp lol

[@lando8913]

I bet that nerd that made magnacut would find this interesting too.

[@jn651]

Dude you rock. So many people treat (no pun intended) this topic as yes/no when there are lots of maybes involved. To say nothing of whether the knives get used hard enough to discern a difference. Bravo

[@cordobadebear]

Great testing and discussion!! I fully agree, that’s why I don’t get excited about overly hard steels, unless they are also tough… pure edge retention only matters if you slice cardboard or rope all day in a controlled manner, but if you start using a knife in a realistic way, who needs a fragile blade that will be difficult to resharpen and strop? Favourite tool steels would be m4, k390, favourite stainless would be cpms30v… looking forward to trying out cruwear and magnacut, don’t care about 15v, s90v, m390 unless it’s heat treated to perfection, also don’t care about 110v or maxamet

[@davidgrise5820]

I'm just learning about all of this, your work and demonstration made it clear and easy to understand. Encouragement and props on what you did and shared. Outstanding job!!!

[@FireCreekForge]

Interesting video! Perhaps they all performed the same in the edge retention test because your tests were focused on abrasion resistance type tests, or is that correct? Since there are several modes of sharpness loss that may be experienced during varied practical use, such as micro chipping, or deformation... 1084 being (basically) a eutectoid steel the austenitizing temp has no real bearing on carbide content in finished product, or potential retained austenite like it does in higher carbon steels, both of which would make a big difference in the abrasion resistance aspect of edge retention. In other words, if you tried this with a higher carbon steel you might see some additional significant differences between the samples. I like your point that RC hardness isn't really the best reference point for blade performance!

[@gunflint1776]

Very interesting results. Not entirely what I expected. Thanks for all that hard work! I'm sure it was a pain in the drain, but we're all more knowledgeable for it.

[@alvinharp3437]

Interesting demonstration, definitely food for thought. A lot of trust goes into the purchase of a knife. I'm very careful with my good (expensive) knives because I don't want to mess up the finish, even knowing the knife is suppose to be very tough. How a knife cuts and how often it must be sharpen is about the only way a consumer can get a sense of whether the knife is satisfactory. I suppose if a knife manufacturer did a poor job with their heat treatments it would eventually get out thanks to social media. They have to do a good job to protect their reputation id they want to stay in business long term.

[@robertshell4176]

Great video. I think this kind of stuff is extremely interesting. Thanks for sharing, always looking forward to more of your content.

[@dcsensui]

Very educational. Most folks would focus on the hardness and not consider toughness. For knives that are used in the great outdoors and need to be dependable, toughness matters. Thanks for taking all the time to do this, and for sacrificing your arm hairs in pursuit of knowledge.

[@1d3d4f5s2d]

Really well done video! It shouldn’t be much of a surprise that these all had the same edge retention. Regardless of crystal structure, HRC directly correlates to abrasion resistance, that’s effectively what it measures. Harder things will resist abrasion better than softer things. The grain size, which is the only variable here shouldn’t effect how the steel wears in a pure cutting application. Hacking through some boards would likely show more micro chipping and therefore faster wear on the poorly treated ones though.

[@baloneylorddonkeyhammer2273]

You are 100% right . The problem with in the knife community is there is alot of people with only 25 to 30 % of the knowledge needed to have a opinion that is relevant. that being what they read on a data sheet that show what a steels maximum hrc is but they don't understand that data isn't realistic as even if you do a heat treat perfectly it doesn't mean that you are going to reach that hardness or that max hardness doesnt translate to optimal performance. And they don't understand that as a knife maker we are trying to not necessarily to reach optimal hardness but optimal balance for the steel we are using and for what the knife is going to be used for . And these same people if the steel wasn't marked they wouldn't know the difference between say s30v and 1095 . Same goes for alot of knife reviewer who drive buying preferences in the edc and knife communities.

[@richardf9137]

Great Insight!

[@OUTDOORS55]

I do think that for the vast majority of knives, hardness is still a top priority. But, for the vast majority of knife consumers, there still needs to be a toughness balance. Since knives are often abused, dropped, thrown around, etc. A full flat ground 1084 steel blade at 63rc and 0.010 behind the edge would make a great cutting blade but don't drop it or open a paint can. Most knife buyers aren't knife people and expect one knife to do everything. 🙂

[@baloneylorddonkeyhammer2273]

@@OUTDOORS55 very . True what I'm seeing is people that watch a bunch knife reviewer content and then want to question why I'm not using 20cv or the like and how come I'm not shooting for 63-65 hrc . And then spend a hour trying to explain to them that yeah it's great steel but not in every application and that I'm trying to strike a balance of maximum toughness with still maintaining decent edge retention because sharpening is always cheaper and easier than a blade that breaks if you drop it or a tip comes off trying to remove a staple .

[@Fattrucker]

You're killing it boi ! ! ! Absolutely fantastic content . The way you test stuff in a kinda scientific real world use way is great . I don't know how else you could test knives any better . Sure all super scientific in a lab etc . But who uses knives like that? Or totally real world with no empirical data gathered whatsoever . Just gut feelings and personal anecdotal impressions . Keep it up . Those close ups are stellar BTW ! P.S. How's the house renovations coming along ? Fattrucker

[@CristiNeagu]

5:57 Dude. I'm looking at those images and my mind is blown. Like, you can see the scratch marks from the grinding. But look in between the scratch marks, towards the edge. That is really smooth. Wow! For some reason I was expecting scratch marks all the way down. So unexpected.

[@vontinkles]

Most of this was above my head, but still enjoyed watching and learning 🙂 Kudos for all the work you put into this. Thanks for sharing!

[@2dthoughts]

Glad to see you posting again Upset I wasn’t notified for 7 months, but glad I’ve got a bunch of stuff to watch now

[@eduardo_scarpini]

Great video and great explanation. Thank you and congratulations. The main problem here is that, when you buy a knife, you will never know if the heat treatment was made well, good or bad... Only if you abuse your knife to the breaking point.

[@scdub]

Interesting results - thanks for taking the time to film and share.

[@watermain48]

I've been watching your channel since the start and just wanted to tell you how much better your knives have gotten with all the experience you've gained. Just wanted to pass that along. I really enjoy your videos, keep it up my young friend.

[@jamesmiddleton6464]

Well done. I think what you are highlighting the difference between edge retention and toughness in a very understandable way. High performance is really a combination of both.

[@Norman_Fleming]

I am not into knives, per se, but I find your videos to be very informative and enjoyable. Nice mix of facts and reality.

[@benwiley3962]

Another great test and video...appreciate all the work you put into these!

[@KnifeCrazzzzy]

This is extremely fascinating!!! Thank you for the time and effort that went into this! 🙌🏻🤙🏻

[@troyclayton]

6:31 Any idea what are the radii like lines we see under the impact points on each blade? #3 seems to show another starting on the left side.

[@matthewpeterson1318]

I would love to see a video on different sharpening angles and the edge retention and edge toughness for the different angles!

[@Claudiu-72]

All depends of sharpening angle, if is more open it will last more, if is more close like, 10-15 degree, it will last shorter time

[@toddcarr.]

Great vid really enjoying the content. I think HRC is a good indicator of what heat treaters are looking for when they know the process was done correctly. If your expecting say 61 HRC but you only get 55 you know something went wrong with the process or the problem could be the steel itself. For consumers when buying from a company they are hoping the HRC is a result from a good heat treat process as an indicator of steel performance during cutting. For the typical person who isn't into the depth of heat treat process it's another statistic that they can slap on a label and say "we did the steel correctly" and the consumer will go for it because a higher number is better right. Just my opinion though. Thanks for the great vid and keep making sharp things fun and enjoyable.

[@lukearts2954]

Love your setup, _especially_ because you're doing "pro science in a garage"... The close-ups keep teaching us a bunch of interesting things. Given you were aiming for the same hrc and found the same "performance" on all 3, would you say the performance is most linked to the hrc, or to the steel type? (i.e. if it's the hrc, similar results from other steels at the exact same hrc would be expected; if it's the steel type, then similar results would appear at (slightly) different hrc in the same steel, and different results in different steel at the same hrc)

[@Donorcyclist]

“Bro science”, not pro.

[@chrisreuther4546]

Great video... so happy I came across it! I am not sure about HRC being equated to a "good heat treat" but I think HRC is meant to be indicative as to the other attributes of the steel. Depending on the heat treat (to my understanding) will help dictate the trade offs between stainlessness/corrosion resistance, toughness, and edge retention. Today, this has become a huge talking point I believe because it attempts to help people compare apples to apples. If I have two knife manufacturers and the same steel if the HRC is at least measurably the same... you have 1 point of true consistency for comparison not good or bad..... just something consistent to view the rest against. But as often said as of late.... geometry is more important than anything else pretty much... but without heat treat do you even have a knife?

[@MrSaltybloke]

it would be interesting to see how the un-tempered knife at 65 hardness compared to the other three, in the same test categories. A fair assumption would be that edge retention was better than the others, due to the greater hardness, but toughness would be rubbish

[@Claudiu-72]

Un tempered blade will snap at once, is like a glass very hard but very weak on elasticity

[@ThisNameWasTooLon]

it would break instantly.. possibly even from just setting it down too hard

[@mikafoxx2717]

​@@ThisNameWasTooLon People think steel is way more brittle than it is.. files are untempered.

[@clf235]

It would be interesting to see how they perform in processing a deer. From skinning, to parting and even boning. At least that is how I judge my knives. Hold a reasonable edge and not break. Keep up the good work.

[@71simonforrester]

That was counterintuitive! Thanks for carrying out the experiment for us all.

[@hansdietrich1496]

Thanks for your thorough testing and not just making up wild statements out of thin air!

[@Thepreppersbunkeroutdoors]

Im wondering if there wasnt much of a difference in the sharpness testing because 1084 is such a simple steel that it doesnt have that much edge retention anyways. (I love 1084 fwiw) Hard to say. But this test was VERY well done, i am hugely impressed by the amount of effort you put into this. Bravo sir.

[@joshuacruce8964]

These results make perfect sense. Wear resistants as far as I know is a quality of the steel, and the hardness. Toughness is greatly enhanced by reducing retained austentite and when a steel is soaked at a higher temp longer it can increase that pesky brittle stuff. At the same hardness and wear resistance the knives should all slice the same. If your chopping however I bet chips would show up fast in the poor heat treat. Also I bet the crappy heat treats lead to less ability to flex when in a bending test. Great job showing how toughness and edge retention are manipulatable factors and how we can improve our outcomes

[@josephshaff5194]

So how we sharpen knives is important. I have a Spear (AlexDrow) I would like to put an edge on. After some research it is 420 Stainless a common material for surgical instruments and kitchen knives as well. I have a dremel or I can use a knife sharpening wet stone (more forgiving and lower temperature.) Now if I use the Dremel tool and heat up the edge too much during the adding an edge process I will change the properties of the material. Then it may not hold an edge as long if I change the crystalline structure due to heat. It can also be more prone to rust in the area heated.

[@robertkoowalski1014]

At the beginning it is said “this video relates to previous video addressing relation of hardness and performance”. Would it not be helpful linking it (if not in video then at least description)? It cannot be found with KZbin search neither by name nor date (as KZbin don’t give precise dates, just “1 year ago”).

[@philipgamboa6134]

Always great watching ur vids. learning something new that makes us wonder and wanna try during lazy winter day. God speed

[@JDStone20]

The reason you got the results you got is that geometry is king when it comes to knife performance. Cliff Stamp cut a lot of cardboard with a mild steel tension bar he ground down and put a coarse edge on. There is a KZbin video or forum post about it somewhere.

[@Thestargazer56]

Very practical testing. Every time I watch your videos, I can't help but chuckle at your quote "...Is this even wood..." Thanks for helping me as I'm lying in my recliner at home after having "unexpected" open heart surgery. Maybe by the time things cool down here in NC, I can start swanging my hammer again.👍

[@CheeseFriesAndCoffee]

You put so much work into these videos. Thank you for all the information!

[@jasonstevens5943]

I think this proved more than anything that1084 is as close to a dummy proof steel as there is! I appreciate how far you took the testing. I don't think you could have done anything different to make it better. With a different steel like 1095 it would have been much different.

[@FindersKeepers88]

Somewhat surprised how they all dulled at the same time regurdless of the heat treat. Excellent job on keeping all of the other factors so even for each knife as the tests progressed. Think I have a better understanding of some of the aspects of heat treat and how the edges react to those tests.

[@Ruoja71]

For tool steels (slightly hypereutectoid alloy steel) 3rd critical point is somewhere arround 860 degrees centigrade. For quenching you want to bring it above critical point 1 where it starts austenitizing (around 790 degrees centigrade) but under 3rd critical point where grains start to overgrow from heat. Depending on the temperature you have to soak it for a different amount of time to fully austenitize - lower temps require longer soak, at higher temps grains recrystalize faster and actually can overgrow also if soaked too long despite being within ac1 to ac3 range. For 800C 10-20 minutes is very correct. 870C might be above ac3 already, so it's rather a no go zone, but you might get away if you just bring the piece to that temperature and quench without any soaking. 980C for 40min - I'm more than very supprised the blade didn't shatter into million pieces at quench. You can see after breaking how swollen the grains are from overheating. The moral of this experiment is for a given steel, hardness comes from crystalline structure while toughness comes from crystal grains size?

[@turing2376]

after being in the "discussion" in the other video and seeing all the work in this one I had to drop a comment for the algorithm at least. great content and video presentation as usual, top notch. was interesting to see real world example and comparison with very low carbide forming steel.

[@joetaylor486]

I am late to your channel and this video. I found this fascinating and it challenged several precepts I had about knife steel and functionality. Also I predicted the humungous grains on the badly treated knife, so a year of a metallurgy degree wasn't completely wasted 😊

[@janneruohomaki2211]

Wonderful stuff. All this hardness/heat treatment stuff has been a bit murky to me. This was the very enlightening.

[@kevinsorensen367]

This gives me hope as a hobby knife maker just starting that my knives have a chance of being somewhat decent 😅

[@donscottvansandt4139]

I have a Moaraknife and it seems to be a little softer than some of my other knives... however it's so easy to sharpen! Where is the middle ground? I love the Moara ... I usually abuse the edge anyway because I'm usually whittling bark with dirt to start ...

[@ChristopherSalisburySalz]

My conclusions from this are that heat treatment details are more important to blade toughness than edge retention. HRC seems to single handedly determine edge retention (within the same type of steel). I'd definitely rather own knife 1 because it will last much longer.

[@marrenmiller]

Very interesting, thanks for all your hard work on this. I'd be particularly curious to see how this impacts higher alloy, higher carbide steels, and particularly stainless steels. I have a feeling that the carbide make-up and corrosion resistance might be more affected on those steels.

[@kellymah1579]

2😅ÿÿĝ ft😊

[@jasonnonanon7206]

By far my favorite knife marker on youtube. Can't wait to get my workshop set up.

[@johnkennedyswenja]

I'm pondering about this video and I decided I really like it and appreciate the time you invested.

[@martinhafner2201]

Edge retention without much side load is really just testing the steel and its hardness - slowly wearing the edge down to dull-ish. There would be very little rolling or chipping unless the steel is extremely weak. So you are testing the hardness, especially when they are the same steel alloy. You got that steel to 60-61 HRC on each knife, so short of extremely weak steel (e.g. walmart knife) they should perform in slow wear mode just about the same.

[@OUTDOORS55]

I did do side load testing. Its in the video

[@bahur47]

this was interesting and even if not completely precise and scientific - it still provides alot of good information. Maybe on a non skandi blade with higher and finer edge the bad heat treatment blade will show more negative effects than in this case . I love these types of videos that you make , I hope you keep doing them :)

[@OUTDOORS55]

These were at 14 degrees. That's about as extreme of an angle as anyone is pushing. The scandi grind is irrelevant as all we are looking at is the very apex in these tests 👍 Thanks for the comment 👊

[@ciscosugui8290]

Thanks for conducting this experiment. I just learned not to worry about the heat treatment of light duty knives.

[@roy.h.barrett]

This is good stuff man. Thanks for sticking with it for the duration of your test... im sure it was beyond monotonous at points.

[@bikerfirefarter7280]

Having broken a few tips, I now grind my 'utility knife' edges to a point with a more robust angle. Still sharp where needed, but significantly less chance of nipping the tip off. The last 10% of the edge angle is increased by 30-50%. e.g. 22deg progresses to between 29 to 33deg.

[@jerrythomas463]

Love your videos. And I can coMpletely relate to the “running out of arm hair” issue.

[@kevin3837]

This was a fantastic video. At some point I would love to see you test tuff steels like 8670 at higher hardness compared to other higher edge retention steels at lower hardness where those lines intersect and see the edge retention.

[@OUTDOORS55]

I do have some s7 laying around as well as some cpm-m4. Although im not sure those two would be a good match up. I think it may be difficult to match the two in hardness to a point where you are not introducing other undesirable characteristics into the steel. Might be worth a try though🤷‍♂️

[@kevin3837]

@@OUTDOORS55 Perhaps an easy one could be like 8670 at like 63 or 62 compared to O1 at 59. I would guess even at those different hardness levels they are still close to the same toughness. Or AEBL at 63/62 compared to another stainless at 59 where the toughness line intersects. Hope that makes sense. I guess my general theory is that tougher steels are more versatile and could come close in edge retention at higher hardness to other steels or left tuff when needed.

[@Ronsonic]

Okay, we seem to have established that hardness determines edge retention. However, you also demonstrate that keeping that edge from breaking depends on quality of heat treatment. Great test.

[@sayeretmatkaal]

Wow. What a fantastic experiment, video & channel ! MOST impressive ...and inspiring ! Kudos Sir !

[@SamMiller-x4f]

Try the paint on or soak surface carbon treatments(per heat treatment).

[@SamMiller-x4f]

I've used these with good results.

[@chazy10]

This video is a piece of GOLD!

[@haitchteeceeeightnineeight5571]

EDIT: You have gone above and beyond regarding the scientific method in this video. Hot damn, sir. Holy moly, from the first 20 seconds of this video I knew I'd like you as a craftsman if we met in person. I like to faff about and shave with a straight razor from time to time. Those are the only blades for which hardness is a primary concern for me because they're exposed to no strain. For my utility knives I like it if they keep an edge well, but they need to be able to do it while I'm striking them with an olive wood bastoni or clipping a bone in an animal I'm preparing to eat.

[@olbaid84]

Seems like this makes sense. Hardness is more how it's holding it's shape, but doesn't factor in the "structure" of the molecules/grains (which heat treating properly helps address), so you're able to retain the shape in things that don't strain the internal structure as much...but once you start doing things that rely more in the internal structure, it starts falling apart. I'm imagining it to being like building a house with proper angles/load bearing/structural considerations vs one that doesn't...it'll get the job done just fine until something tests the structure, and it'll collapse or various parts of the frame that was under odd stress will pop out.

[@chrishoesing5455]

Very fun video. Now try 3 new ones, same metal , shape, and grind, but this time all 3 with the same good heat treat, but tempered to 3 different hrcs. Then the same tests.

[@pauljs75]

If you still have some kind of uncertainty or doubts, I'd suggest seeing if you can do a collab with Project Farm on testing the different blades. He's pretty through and open about his evaluation process and documenting it for everyone to see. Maybe his approach could answer some questions, in either confirming things or making any differences more apparent. Maybe make it a blind study on his end, so all he knows is getting blades A, B, and C - and then do a reveal after the results come in.

[@hisnameisrentoo]

Wow. This is great stuff. Thanks for sharing your findings! The world needs more vids like this.

[@stuartdavenport2952]

Good video. As a maker, I get enraged by the use of the term "edge retention" testing when the test you are performing (slicing stuff like cardboard) is NOT EDGE RETENTION TESTING!!! For crying out loud. It is called "wear resistance". NOT "edge retention". Actual edge retention is the sum of all of the properties, toughness, hardness, wear resistance, apex stability, corrosion resistance (to some extent). And that is why you are getting similar results with all 3 knives in "wear resistance" testing. Those other factors, like toughness, apex stability, etc aren't going to have a noticeable affect when slicing stuff. Grain size plays very little role when slicing into stuff like cardboard, but grain size has a massive role in stuff like tip strength and apex stability.

[@stantilton2191]

A valiant effort to a very complex subject. There are so many variables in this subject, it's nearly impossible to have a black and white answer. Frustrating as it is I think you've conveyed the information well. Don't beat yourself up over the rabbit hole of details possible here. In the end, if you aren't happy with your heat treat, retreat and repeat until you are. Well done.

[@bobobosco8051]

I use 1084 vs 1095 because I have found out that the 1084 seems to be more forgiving in heat treatment vs 1095. The 1095 can get a bit more brittle if an error occurs, while the 1084 seems to withstand a bit better. I kind of wonder if it is due to the carbon content. Higher carbon= shorter crystalization making a harder blade, and during the tempering stage if you start with smaller crystals you reduce the ability to grow a proper lattice in the metal is you have gone outside the perimeters of the steel. Where as the 1084 has a slightly less carbon content which allows for longer crystal formation making it a little more forgiving in the tempering process. Hell, there are a multitude of arguments that can be made in this discussion, but my choice is a nice 6" blade full tang 1084 knife that I feel comfortable using and have less concerns when having a home blacksmith producing a blade I like.

[@icusawme2]

Wonder if better tempering on the poor austentizing would repair the grains structure? Thanks for your hard work on this.

[@Kinglobo]

Very informative. Gives some idea to people why 2 knives from the same steel and similar HRC can perform totally different. I got 2 mora knives from the same steel and one of them performs bad...

[@haroldnutt8837]

Quick question Alex, you’re using 1/8” 1084 & probably annealed steel from knife steel supplier, then austenitized. That one time is the only heat to the steel correct. BTW hope you’re feeling better. Thanks

[@bestrong1240]

hey great information thanks for your time I got a question for you I seen a Japanese knife maker making some like 10 inch knives and at the end of it he set up a piece of metal and a vise and he was splitting the metal with his knife and not denting it or chipping it why is that

[@CarnivoreRonin]

That blew my mind. I would never have predicted your results, thanks

[@martinhafner2201]

And this is why we have destruction testers for "hard use" outdoor knives. The big issue is how easily they break. People sometimes laugh at the destruction testers, but they bring an important service to us. For example, a good heat treat will yield a knife that cuts well and can also take body weight "step" loading. A TOPS knife may have a slightly low HRC and need sharpening more often, but is unlikely to break in the field. The extra insurance comes at a cost. We're usually wishing for the best compromise rather than the safest knife, such as you get from a careful heat treat and a good hardness. A bad heat treat such as on the many botched Asian Schrade outdoor knives may break in half from just a bad landing when throwing the knife into a tree. So it should come as no surprise that most throwing knives rarely get up to 55 HRC. A sushi/sashimi knife may be made pretty hard, with a very shallow angle, but it will not see any rough use by a competent sushi chef. It would fail these tests, but no one would notice or care. If the angle was extremely thin, then these toughness issues would become more important.

[@aaronhope8366]

I appreciate the comments about choosing a definition of "knife performance" and that there are different standards. I think it removes the ambiguity from the conversation. The granularity shot of the crystalline structure was a great one that reminded me of ice cream. Sure they're both cold, but the one with ice crystals ain't so good.