Why Knife Makers Should Break Their Knives
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- เผยแพร่เมื่อ 28 ก.ย. 2024
- Why Knife Makers Should Break Their Knives. A journey into heat treating 1095. In this video I talk about heat treating and its affects it can have on a finished knife. Bad heat treatments do exist and good heat treating may not be as simple as following a specific set of times and temperatures. Not all ovens are created equal and not all forges heat the same. Testing your own knives with your specific heat treating recipe is super important. And this goes for any steel type you may choose to use in your knife making.
This is also why its important to use the correct kind of steel for your heating treating operation. I wouldn't not choose 1095 for any kind of knife making purpose if I didn't have an oven to heat treat it.
Soaking at temperature in a forge is just not possible unless you have some way of knowing the temperature in the forge. Steel color can change due to lighting conditions. And even experienced knife makers cant tell exact temperatures by color.
If you are a beginning knife maker dont let this video discourage you though. Get some 1080/1084 steel, heat to non magnetic and a little more, then quench. DONE. No need to soak to get full benefit.
About⬇️
Hi, Im Alex, im a knife maker and TH-camr, based out of southern Pennsylvania and my youtube channel is Outdoors55. This channel started as an outdoor backpacking channel, but quickly grew into a knife/ knife making channel. Everything I do on my channel is family friendly. I primarily focus on knife / knife making videos but occasionally throw in something different. Thank you for watching!😀
#knifemaking #knife #knifemaker #outdoors55
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Good work. The heat treat conclusion is correct. However, you are misinterpreting what you are observing. You are not looking at the grain structure. You are looking at different types of failure modes. In a brittle fracture, a crack forms and cleaves through the material, leaving a smooth finish. In a ductile fracture, the material distorts and "necks down". This simultaneously creates a rougher looking surface and simultaneously the effective cross-section is reduced. Eventually, the cross section is reduced enough that tensile strength is exceeded. When that occurs crack forms, the crack quickly propagates through the material and the knife breaks. Part of the fractured surface will be rough and a part will be smooth.
You can tell all about your heat treat process by simply looking at the fractured surface and estimating the ratio of ductile to the brittle fractured surface.
As a side note, the ideal condition would be for the cutting edge to be hard (but not "brittle") and for the back to be more ductile. That would create a knife that would both hold an edge and not snap under heavy loading.
To observe the grain structure, you would need to cut polish the surface until it was mirror-like. You would also need a microscope. Sometimes you need polarized light and an etchant to cause the boundaries to "pop" out.
In any case, good job.
This guy forges
Do you teach? 😅
@@gamer.004 No, I did research in fracture mechanics.
Ductile definitely isn't the word you meant. Also, you wouldn't necessarily want a brittle edge. It doesn't matter too much how tough it is, but a higher toughness means you can repair it more easily. Brittle or tough, the priority should be making the edge strong and hard
@@goodguykonrad3701 You are correct. I did not think this lay audience would be interested in the technical definition of toughness: The area under the stress strain-curve or the ability to absorb energy before fracture. I simplified the description to a ductile-brittle analogy. For a specific heat-treated steel, the more ductile heat treat is almost always tougher than the more brittle heat treat.
I just came across this. It is a better explanation than mine. www.materials.unsw.edu.au/tutorials/online-tutorials/2-cup-and-cone-fracture#img
- Any idea on how to succinctly explain toughness to this audience?
10/10 for going over and above what any normal human could ever be expected to do , so it's a gold star from me .
Kinda. I mean, lots of valuable effort, I love that he did this, I agree on that part.
But plenty of research students all over the world are expected to put similar effort into their respective fields of study to earn whatever degree their aspiring to get. The difference is, he did this out of pure interest, which makes it even cooler. If he continues he might get enough data out of this to write a scientific paper.
Also the idea that this is far beyond what any normal human could ever be expected to do I feel is a terrible statement and reinforces the reduction of work ethic for quality we see. What we expect these days sure. I do love though that he dov down into trying to figure out what was happening.
@@ruolbu Not really. In material science, the things that he has looked at are pretty much common knowledge. My respect towards him putting in the effort but nothing he has done is new or groundbreaking. If he knew where to search, he could have read this in some very old books (or of course more modern literature).
The fact that you believe this is so far above what a human could ever be expected to do just shows how little you strive for.
@@shawnpitman876 OK Shawn the irony of your statement is my 10/10 was my support in a positive light . While your poo-pooing , reflects in your 5 subs and zero , yes that's right zero content , yet you feel the need to poo-poo others , telling us just how little i strive for with your zero content channel .
even car makers crash their cars. this is common sense
Even Samurais who live by the sword, die by the sword. Oh wait, that's Seppuku.
Weaboo
xD
@@blackflamelvl2007 u wrote sudoku wrong
What about dildo makers?
Oil temp is probably playing a role here. If you want to know for sure, do the same test and use 5 different buckets of oil.
this was my first thought also
or different types of oils because on this depends how quick will metal cool off, thats why we dont use water all time for this
Can you use lard instead?
The warming the oil, the more malleable the blade.
The colder the oil, the harder the blade, but also more brittle.
Oil temp is probably not making a difference
I love you don't mind destroying things you made to make sure they are up to snuff. No one should have any reservations buying any knife you make. Great channel. Keep it up.
Great dedication to the craft. However, you're not actually looking at grain size. You're looking at fracture surfaces, which generally occur along grain boundaries. To look at grain size, you must polish the sample, apply an etchant, and view under a microscope. Also, a factor that's missing here is the hardness. It's very likely the pieces that were not soaked 5 minutes or more did not reach full hardness capability, which defeats the purpose of a high carbon steel knife. If you're not soaking it adequately to achieve the steel's potential, grain size doesn't really matter. there's a point of diminishing return where ultra fine grain becomes a problem as you lose hardness. I got on the grain size merry go round a while ago too but then I got off after I learned a little more... :)
Theres a lot of factors missing here that i cant necessarily test with my limited equipment. All of the pieces however were saoked minimum of 5 minutes. Theres still a possibility that full hardness wasnt reached. I dont have a hardness tester so i dont know for sure. Thanks for the comment 👍
Great video Alex, I'm glad you talk about this subject because heat treatment is what makes a knife good imo.
I studied metallurgy last year and what you say is true. Soaking time increases grain size for simple carbon steels. Alloyed steels can sometimes reduce their grains with soaking time. And the higher you go beyond the critical temperature, the bigger the grain.
What I would love to see is the grain structure difference between a forged blade and a stock removal blade. I have no idea about the result...😅
Question. Would the elevating oil temp throughout the process of quenching cause the steel to cool slower and allow for larger grain size?
Curtis Barkes I was thinking the same thing I’m sure it could play a fairly large role in the results
No, oil temperatures were monitored throughout the testing. 110 for the low and 155 for the high👍
@@OUTDOORS55 right on
if anything, hotter oil would be more fluid and cause the steel to cool faster.
@@Jiminycroquet never heard that.
Awesome info!! Now I’m going to have to do a bunch of testing myself. I’ve done destructive tests on knives and it always makes me cringe to put all that work in just to break the thing in half but i think its a very important step for anyone wanting to ensure quality. Thanks again this video was the most informative heat treating I’ve seen on youtube particularly of interest to me because i use a lot of 1095.
Thanks my friend! I agree its a necessary evil. 👍
@@OUTDOORS55 Were do you get your stainless steel foil for keeping the O2 out of the "Quenching"? Think it will work with a atmosphere propane forge or and forced air propane forge? I can run them rich so that I greatly reduce the O2 but was thinking that adding the foil might save me even more addition Carbon content. Thoughts?
Nice job showing what diligent knife makers go through to understand the steels they decide to work with. Tested my share, still do, just to make the processes are still valid.
Dear Outdoors55,
I love your investigative nature and believe that you are following the right tests to ensure the quality of your knives!
I'm from Germany and am currently in my second semester of my "Ausbildung" (sort of a vocational training) that specializes in metallography, so eesentially the analysis of grain structures, impurities and the likes in metals. Now I'm by far not an expert yet, nor will I be for a long time but it is channels like yours and other creators that pushed me to pursue this career and it has been nothing but rewarding!
I've talked about heat treatment with one of my teachers, since I'm so fanatical about knives, and according to her about two or three normalizing cycles at about 30-50°C (I think thats about 90°F to about 120°F) under quenching temperature, followed my multiple quenches (without tempering in between!) ensures a really fine grain structure and positively affects toughness whilst not affecting the final hardness after tempering. Also driving the temperature differential up is really beneficial (cryogenic treatment after the last quench), as that temperature difference allows for a stronger setting in the crystalline lattice and by thermal compression allows for 'clearer' boundaries.
Then after all that and tempering you should be rewarded by a really great performing knive.
Thanks a lot for your content and greetings from Germany !
edit : sorry for the long comment ;)
Multiple quenching is something that has been done in knife making for a long time. I forget who was the first to really put it into practice. From the knife research ive done it seems to be the best way to get a very fine grain. It will definitely something ill do in the future. Maybe a follow up to this video. Thanks for the input!! It definitely intrigues me more😂 im also wondering if more normalization cycles slightly under quenching temperature would refine grain even further without multiple quenching. Seems some people swear by it. Thanks again 👍👍
@@OUTDOORS55 I think you can refine the grain a lot but don't forget that if you go to far on the refining it gets harder and harder to fully harden the steel.
Hallo in welchem Beruf machst du deine Ausbildung?
@@evias9943 Der Beruf heißt Technischer Assistent für Metallographie und Werkstoffanalyse und wird nur in Berlin und Solingen angeboten, meine mache ich im Lette Verein Berlin
magst du meine messer härten? :D
Hmm Have you thought about the temperature of the oil you are quenching in ? Each time you quench a piece of steel in that same oil you are raising it's temperature and each peace that follows is quenched in hotter and hotter oil. Oil that's lets say 90 degrees Celsius will quench steel quicker than same oil at room temperature of 25 degrees even thou its hotter. Have a think about that ;)
Yeah, just a bunch of BS. Maybe if you want consistent metal work, use consistent procedures across the entire build cycle including the oil temp you are quenching at.
Thats what i was thinking... evertime he opens the door he will loose some heat aswell...
Test the oil temp? You quenched sequentially for the first test, which increases the oil's temp, right?
He replied to another comment saying he monitored the temp. 110 low and 155 for the high.
I'm a machinist and have done a fair amount of heat treating of various metals for various reasons. I think what Dan Pedersen said was correct, but wanted to add a couple suggestions to help you fine tune your process. Get a hardness tester, and perhaps something to measure torque as you are bending those knives to failure for more accurate diagnosis of what's going on. Unfortunately, my experience is with tooling steels and oddball alloys, so I really don't feel qualified to add specific insight into normal carbon steel. In my personal experience I haven't seen longer soak times lead to bad results. For me, I have found the tempering to be more critical but again, different materials and substantially different thicknesses.
it was very cool to be able to SEE what everyone is always TALKING about. awesome!
I've never made a knife before nor do I intend to. I'm not sure why I'm here but I'm glad I am.
I think a statement you put in text on the screen near the end sums it up best. Don't do more than 1 blade at a time. Not saying I know anything. I know I do the best job on 1 thing. Rather than more than one thing. Might be the same for the forge. Is this metal all from the same purchase? From the same company? Just thinking not consistent metal through out. Or even just a bad batch of metal. That would be saying the problem wasn't your fault. I just end with more questions than final thoughts. Still a really great video. I did enjoy the experiment you did. You explained it well. Sometimes in doing something their isn't an answer. You might repeat that and get a different outcome. Your work is great. Keep up the great work. 👍😁
A lot of 1095 shows inconsistent results when comparing it to the data sheets because a lot of 1095 has minute amounts of alloying elements, such as nickel. I have had consistent results when ordering steel from the same company, but some slight variations with others (Amazon was a steel ordering platform for a while). I do not have a temp monitored oven for quenching so I only have results based on "feel". 1095 cools very rapidly so its possible when you are pulling the blades out one at a time to quench, there is a drop and rise in temp for the others. I would be interested to see one blade at a time. In my experience I have not had issues soaking for too long, but I honestly can't think if I have soaked at around critical for longer than 10 minutes, again "feel" sadly I never had a watch near me.
Tldr
Try the soak time test one piece in the oven at a time, might look different.
Yeah not all 1095 is the sam. This specific batch is only 0.9 carbon. Thats the minimum needed for it to be called 1095. Ill have to look to see what other elements are in this batch. I think thats why alot of custom makers seem to stay away from it and use a steel thats more consistent like o1 or cpm steels that give you specific info on heat treating.
Ecspecially like his recommendation of the one at a time soak test
Love your channel. I’ve learned so much from you. I’m compiling a list of materials to start my first blade.
“I put my ENTIRE 150lbs on them” 🤣🤣 Great video man. I am really enjoying your strength test videos. Being a total amateur knife maker, JUST getting in to the hobby, these have been very helpful.
Great vid man very informative. I’ve been making knives for only a year now more for hobby. I know the heat treat process is important, but who is actually going to pound on metal and try to cut logs with a knife? My question how much effort should I put into the heat treat if I want to start selling knives?
it depends on what you want to sell? top knotch knifes at a premium price or just nice knifes for a reasonable price but not as good as the first. Also depends on what kind of knife you make, a thick sturdy knife like 4mm or so probably has not that much to fear of a less than ideal heat treat, but if you want smaller knifes bending and breaking becomes much more of a thing to consider. in my opinion one should always try to get the best results, or at least with the options given to you to produce the quality you want. Everyone can buy some chinesium steel and make knifes. Good knifemakers make knifes that cut through chinesium knifes.
I tried to normalize myself once, back when I was in my late 20's...OMG, talk about a shit show. That shit just wasn't happening.
I just finally realized it, your videos are awesome, finally a down to earth genius, who makes since and isn't a complete knob.
Thanks pal! 🖤🔪
I just wanted to thank you for taking the time to do all this and sharing it. It was a very informative video!
Thanks! It was a necessary evil so I might as well film it🤷♂️ Thanks for watching my friend!
Good video, the art of forging. Murray Carter also explains this well in one of his videos.
I am very impressed. I love the extra you go to to improve your own knowledge in knife making. Keep up the excellent work man. You are doing great!
I love how methodical you were.
I watch your videos with a lot of interrest and also learn alot.
What I do not understant about this one, humans from different countries all over the world have learned how to work metal, create swords and knifes for 1000s of years, why would you want to start learning from scratch on your own, ask basic questions on Social Media that could easily be answered by going to a knife making company, learning the basics and expanding your skills. Another option is going to Japan like others do to learn from a Master knife maker than utilizing what you really want to do... Make your own brand of knifes.
I think you are making this beautiful journey of yours much more complicated than it should be. We only live roughly 80 years, go and learn this 1000 of years old skill from those who know best than use your imagination to make it your own.
Respectfully with not negative intention in my words.
Because most heat treating is trade secret stuff. Knives have very specific purposes. And most steel that is sold and used in knives today are not meant for knife specific tasks. So knife makers have to learn their stuff for them selves. Not to mention every oven is different. Making and breaking blades is still part of the quality control process. Metalergy is an ever changing thing with new steels and different ingredients being used to make the steel. Not all 1095 is the same. Different alloys are added depending on manufacturer. And that can affect heat treating. Like i said its a pretty in depth subject 🙂 Thanks for the comment👍
Still looking for a japanese master who can explain bohler m390 to me ;-). Basicallly, all of us 'knifemakers' are continuously looking for info from those past millenia of knowledge. And every now and then someone even ads to that knowledge. Sometimes without being considered a mastercraftsman or working for a knifecompany. It is by testing and evaluating yourself that you learn most and occasionally something new. 20 years ago nobody used cryo (at least that i knew) now everyone does...
G'Day,,After watching you Film,,I Have had problems with parent metals not being the same all the way through,First hurdle,,The other thing is quench liquid temp,
now depending on the original steel,,different Heat treatments are recommended,have seen a full furnace go to scrap because of over heating,,maybe 50 ton of high quality scrap,,
for example when making steel grinding balls,,they air cool and then quench,,but quenching water is at 50 c,these balls come hard and tough,
Now in the rod mill,,the quenching process is highly adjustable,,have seen rod from mill go through the tying machine and turn to dust under 40 ton pressure ,wrong cooling schedule,
it may be to your advantage to test each piece before manufacture of blade,,
Sorry for the long winded comment,,and late viewing,,But i do like the way you went for it,
I think like this guy. I tested in my wood shop the most common ways to assemble a ply wood box for a cabinet, and knocked them apart with an ax. It was clear: glue or rabbets or brads are not nearly as strong as properly drilled wood crews.
I'm not sure but I think you need to reach austenite temps before the grains can grow. I think you can keep steel at below critical temp for a long time and not see much or any grain growth.
by not quenching in the same temperature oil for each piece you change two of your variables to know it is the soak time the oil needs to be the same temp for each piece
My guess was the temp of the oil by the last quench the oil temp would have elevated a lot, If you have a bigger quench tub it would be better for consistency because the thermal capacity would be higher worth a try, that would allow the steel to cool faster to a lower temp
Just saw a comment voicing that concern, but he replied that he carefully monitored the oil temp. 110° for the low, and 155° for the high.
check out he oil temps, soak time seems as important as quench temp. room temp oil cools the steel faster than oil that has temp raised after several quick succession quenches.
Jokes aside; I think there are two things you need to control more accurately: oil temperature and quench speed. They both affect kind of the same thing which is recrystallisation.
When quenching you're looking to maximise the rate at which the steel cools down. If your oil is warmer (from previous quenches) you'll get less of a temperature differential which translates directly to fewer degrees cooled per second. In the soaking process the steel is oversaturated with carbon and when it cools down rapidly it will form martensite and carbides, both of which are substantially harder materials than the austenite you started with.
Quench speed does kind of the same thing. Your piece of metal is really hot compared to its surroundings and it's losing heat rapidly. Think of the small time it takes to draw out the piece and into the quench as a mini normalisation. If you fumble around, close doors or do stuff like that you could start to get the carbon to dissolve back into the metal.
I propose two tests.
1) Use same batch of steel, same temperature, same soak time. Have oil baths at different temperatures. You could heat one up (be careful with hot oil though, please), have one at room temperature and refrigerate one. See if the grain structure differs.
2) Use same batch of steel, same temperature, same soak time, same oil temperature. Quench one piece really quickly - as fast as you can, contemplate on the second for some 5 seconds before quenching and really ponder about the meaning of life for 10 seconds on the last piece.
This way you'll know whether the cooling rate affects your grain structure. Additionally, you'll know which affects more: the oil temp or the time it takes to quench the piece.
I'm sure the answers actually do exist somewhere out the on the internet but I only did some 10 mins of googling. Keywords you could use: phase diagram, recrystallisation. Also take my thoughts with a grain of salt because I don't actually have a degree in materials science / engineering, only did some courses.
Oil temperature was monitored 110-155 within the range of the oil . And thers no accurate way to control quench speed. The piece simply gets shoved into the oil.
just a thought, your oil temp will be rising every time you quench a piece in it. I think this may also have a factor even if only a little one
I made a small knife using 1084 steel. When it was time to heat treat I made a fire bc i dont have a oven yet. I threw the knife under the fire and let it stay there. It was in the fire for a great deal of time but it didn't turn orange , but I decided to quench any way. I quenched it in a water cup with water, mom wasn't to happy about the cup. But any way I put it in a vice to finish up wen the blade simply broke off. It did have a large warp in it but I noticed the blade was extremely grainy inside. Huge grains wish I could show u. Not quite shure how this has happened
Just a thought, but why not try leaving a little extra metal when you do your treating. Then you can snap, or cut the little extra area off. And know for sure that the grain is good, without having to destroy your good knives just because you get one that didn't work correctly, and turned out bad.
Just a thought.
Late to this party, but is it possible that the lack of normalisation on the first 5 test pieces affected the results as well? My understanding is that soak time should not significantly increase grain size, at least not at heat treating temps. I may have to try this myself.
here's my guess toward why you found what you did toward the end. im a welder (well was) and back when had to do my cert test my teacher taught me to always air cool the plates. why because the grains are more solid and longer this way. so my best guess is leaving the metal overheated for 15 mins allowed the grains to have a similar effect as air cooling. though this is a just a blind guess and i haven't checked my metallurgy books in yeats
This is your first video I saw and what can I say, you earned my sub right away :)
metal bobbles microscopically creating grains. maybe a long period of low minimum heating where it barely or maybe will be slightly reaching a red state where the metal can perfectly blend, maybe it can obtain a smooth grain. i have no experience what so ever lol
Well gotta be said see I love green beetle, top stuff, Walter sorrel too dry, but you my friend really give so much useful information in a modern, and damn funny but hellish informative and interesting content. You clearly think so much about your content. Thankyou for your great efforts love your posts.
Thanks my friend!! 👊
if you had a magnifying glass i think it would be a lot easier to see the grain structure.
Interesting, I always thought those 'grains of metal' were microscopically small...
At 1:15 we can confirm that Alex is in fact, a member of the vape nation
haha no😂
@@OUTDOORS55 I'm glad you are not. I'd have to unsubscribe if you were =))
You know vaping causes cervical cancer in men
Reading comments as I blow huge clouds across my shop.
I just had to say that All I understand about this is you scared the Shit out of me breaking those blades! I'm Not a knife maker, but my neighbor was and he broke a blade once that sent a shard straight through his subclavian artery! Luckily myself and his son (a SF medic) controlled the bleeding until the PM's arrived. Please wear some protective something 🤔
Yep, I was shielded for them all in some way. Thats a lot of energy stored up in there👍
I use a heavy apron a chainmail collar and face shield when i break mine
there is also the fact that maybe you are heating up the liquid you are quenching the metal in. you are putting something that is 1475 degrees in it so the liquid is probably much hotter at the last quench.
That is a lot of information for a guy who just likes to use knives and watch Outdoors55 but essential to the people making them. Great cliff hanger at the end... curiosity killed the Kev
Yeah, one could write a book.. id read it if they did😂 Thanks for watching man👊
Looks like grain growth happens from length of time, I thought it just occurred from higher heat, what do you think of normalizing blades at quench temp? I was under the impression that soaking at dull cherry for long time was a good thing, I’ve read it shrinks grain structure. Thanks for doing this video, just subbed, keep it up!
Once the heat treating process is started, there are no retarding impacts and crystal growth resumes unhindered.
The larger the crystal structure the weaker the steel becomes, the sooner the blade is quenched after proper temperature is reached, the better. The grain growth occurs very quickly, only after a few moments, the enlargement of the crystal starts. To prevent any problems, quench as soon as possible after the heat is even.
These problems are lessened if you keep the the time the metal is at critical temperature to a minimum.
Tip from flash (probably the best welder in the north sea)
This is completely steel dependent and not applicable to all steel including 1095
A Scientist doing Science ! Awesome. Great to see this.
Except he is doing it wrong....
Please Explain. Doesn't impress anyone unless you detail how he should have done it 'right'.
You might want to get in touch with another youtuber with access to a microscope and use a stricter method for heating and quenching (everything is a variable -time spent heating to temp, time in air before oil, the orientation of the grain when heating and quenching) with something so precise as grain literally the smallest differences can have a massive affect. It would be near impossible to get perfect results but you could reduce the margin of error in order to perfect heat treatment and quenching not only to increase the quality of your blades but possibly also help the market as a whole. You could make the next big discovery in metal treatment so don’t stop now
I would bet your oven is about 25 degrees hotter than it reads, Back down to 1450 and you will be able to hold soak for longer without grain growth.
I like this. We always learn new things when we experiment.
Just thinking out loud, the first blade that was problematic have not even been normalized or progressively grain refined. The two other blade had not been normalized either but lower time in HT oven may have limit the grain growth. Maybe the fact that in the latter test pieces you refined the grain to a much finer degree the time spent in the oven wasn't as relevant. I work with 52100 and after the grain refinements step the time I spend in the oven don't seem to affect the grain too much.
It could be a normalization issue like you say. That could definitely be plausible. I might go back and try again with pre refined pieces and try the first test agin. Thanks for the suggestion 👍
I love your videos! Really helpful. I didnt know you make knifes, too. Beautiful.
Hi, I dont know anything about metal and structures, but iv seen that most grained steel was always soaked in oil last, if u use the same oil all the time without breaks maybe its becouse of oil temperature for example "knife 1 cold oil" "knife 2 hotter oil" "knife3 hot oil", if oil was the same u can repeat experiment with first knife 10 min, sec 7 and third 5. and sorry for my eng i know its low ;P
One potential flaw I saw was the quench oil itself. I found the testing to be very interesting and thorough except for the quench. If you infact did these one right after another then your quench oil was way to hot after the first quench. The oil for a quench needs to be between 120 and 150 degrees. After quenching knife 1 your oil was probably aroound 50 degrees. It needs to cool down to 120 to 150 again before quenching the second blade and then again and so on. Unless you actually accounted for this and just didn't mention it. I have found out the hard way that it makes a difference. It's a pain in the ass when having 2 knives to quench and needing to cool the oil first. I have actually gone to having 3 quench tanks so 'i can do atleast 3 blades before having to worry about il cooling. It seems to take forever for the oil to cool naturally after getting it over 200 degrees. Just something I noticed in the video and thought 'i would point out. I enjoy your video's and am looking forward to mre like this because I am looking to better my heat treating as well. Thanks!
I forgot to mention it in the video but the oil temps were monitored. Starting temp was 110F ending at 155F after the first three blades. It doesn't seem like much gain but they were thin blades and the oil can was sitting on a 17 degree floor, so im sure that helped. Oil temperature shouldn't affect grain size anyway..it could affect hardness, but definitely not grain size. That wouldn't explain the other tests either. The pieces were much smaller and barely raised oil temps whatsoever. Some others think its a normalization issue. There may have been smaller grain in the normalized pieces, where as the first test could have been starting out with already enlarged grain. Just a theory for now🤷♂️
In my opinion soaking isn't necessary for a knife because its relatively thin. If you're looking at HT charts they advise you to soak because they want that consistent temp to penetrate through the entire piece. Better to just quench the blade as soon as it hits critical. Also, check your oil temps. Needs to be consistent every time.
i think with 1095 you have to get the carbides back into solution, this takes a bit of a soak. but im no metallurgist.
A short soak is required with 1095 to allow all the carbon to dissolve into solution.
Ok. Try it without a soak and see the results. try it with a soak and record that. You'll find that soaking a blade blank only causes the grain structure to swell. The charts that tell you to soak aren't made for knife makers.
If you're heat treating properly, soaking at the right temperature shouldn't have any negative effect on the steel no matter how long you soak. And not scales of minutes, but scales of hours. There are people who have soaked O1 steel at a specific temperature for lengths of both minutes and hours, and noticed no demonstrable difference in properties (for example).
This isn't o1, its 1095.
@@OUTDOORS55
I know.
Overheating you also stand a chance of decarburization in certain areas of the blade giving you inconsistency in hardness. At least that's been my experience when hitting hot spots in my propain forge. I've since got that ironed out.
Edit: severe overheating. 😆 but you'd be surprised how quickly that can happen in a propane forge. Something I'm sure you have experience before getting your fancy oven there. Nope not jealous. Not jealous. Nothing but happy for you you yoooouuuu. 😉👍
Yes I have seen some decarb issues. Im guessing I was in the range of 1600+ degrees for that. 😂
@@OUTDOORS55 hey like I said, I had some hot spots... really hot spots.🙄 or it may have to do with me being a tad impatient and jamming the blade directly into the flame. *Cough* while using mapp gas. 🤣
Haha i was talking about me😂 i may have WAY over heated a blade or 6... even in my mini forge🤣Lost track of time i guess😀
When metal is quenched,does the metal contract? Does metal quenched for longer result in a more choppy, uneven contraction as its more hardened by that point compared to a blade quenched for less time? Are the longer quenched blades less malleable by that point and therefor fighting against its own strength?
There is a app called heat treat for the phone that gives fairly specific heat treatment and temperatures
Would it have anything to do with the fact that the tempurature is changing, and it's effectively waiting for the temp to stabalise before the material can do its thing?
To see razor edges you have to go to Japan (samurai swords) and China. They have been making razor edge swords for a thousand years and have the knowhow. Special stainless steel and layered metals.
I wonder if the heating of the oil before quenching is making a bigger grain structure. The oil gets hotter with each piece
So "soaking" is leaving it inside the heat? example, 5 minutes?
Correct
hey alex great video, i was wondering could you possibly fix (weld) a knife that has been broken right in between the tang and heel of the blade or maybe you could fix the fine grain knife that you show in the video. love see you fix the blade or even a make tutorial for how to fix broken knives. thanks
indentation hardness tests would help quantify the results but BRAVO
What music was used in the video? I really like the song at 11:00
Gavin Luke - Wild Slide
Normalize the steel with the oven, get the grain as uniform as possible and allow to air cool.
Then hook yourself up some blow torches to heat your knives evenly, and use a strong magnet to hold them above your quench oil.
When the knives reach critical temp - they'll loose magnetic properties and drop into the oil to quench.
Let them fully cool in the oil, at this point they'll be way too hard for use, brittle as glass.
Put them back in the oven to 400-500 degrees, let them air cool to temper.
It's a machinists's trick to making critical pins and load bearing rods which have to be very strong but also not hard enough (brittle) to shatter under the load. You get yourself as uniform a grain structure as possible with a hard surface which will resist marring or being gauged by other steel parts and yet it's not so hard that it will easily bend or shatter under strain. It's usually done for small pins or rods, but if you used an earth magnet and stuck the tip of the tang to it, then allowed 3-4 blow torches in a circle to evenly heat the blade it should work pretty well for you. This process would give you uniform and exacting results.
@@awashburn6944 As far as I know: cementite is caused when carbon is permitted to migrate out of the iron alloy by cooling slowly. By doing such a quick quench after reaching a nonferrous state the carbon isn't given the opportunity to diffuse and instead becomes martensite.
@@awashburn6944 Ah, see - this is why I like longer in depth discussions on platforms which allow for it. Now I see what you're saying, the air cool after the normalization would allow for too much carbon to diffuse before heating up for the quench.
Taking that into consideration: I agree and believe you are correct. Sorry, this isn't something I have to deal with on a regular basis, anytime I have to make critical rods or pins I start by buying materials that I don't have to normalize. There I was only concerned with what the original poster had displayed as the results in steel from him personally performing the normalization process himself.
This is an area I don't have to deal with for my purposes. Benefit of high end fabrication and manufacturing: someone else has already performed these tasks and I start further along in the process.
So, if I've understood the issue you brought up: a better recommendation would be to normalize, cool, then heat up and maintain high temp to allow for the cementite to melt down and reform and only then do your quench, is that correct?
What do you mean by soak time? Do you keep it in the oil for 5 mins? New to blademaking, i want to learn as much as i can 🤟
Thank you. Saved me some metal. 😅
It would be better if you described each step of the process as if you are talking to someone who has no understanding of what you are talking about. What is "soaking period"? What are you soaking it in? What are you doing after soaking? How does this affect the steel? Is it better to not soak?
Look it up... If you do not understand the nomenclature, research it so you can follow along.
Pause the video, google the term, then resume the video.
Soaking is the amount of time the piece is held at a specific temperature, and it is "Soaked" in the oven.
Why not do this with the tip instead of breaking the whole knife. I usually try to bend the tip to see if the kinfe is either super hard (tip will break support), or super flexible (tip wil bend and come back in place - or not)
@ 15:30 you said, "Overheating and soaking time does cause grain growth"
If you learn to read an iron-carbon phase diagram, and how iron changes phases, you would understand why that sounds absurd.
You can't really overheat your knife, unless it gets molten and turns to liquid.
On the iron-carbon phase diagram, you will find several different areas of the graph. Drawing a vertical line for 1080 steel at 0.80% carbon, you can follow from 0 degrees up through all of the different phases of iron.
When iron changes phase first, it remains solid, but the gran structure reorganizes completely. This is not an instant process. This can take hours, depending on the steel.
If you hold the steel at a transition point on the graph for long enough before dropping the temperature, it recrystallizes to the lowest phase on the graph.
However, if you heat the steel up to glowing orange and hold it there, the crystalline structure has completely rearranged. When you quench the blade, you cool the crystals so fast that they don't reorganize to the lower level on the graph.
This is where you move from the iron-carbon phase diagram to the TTT diagram. The TTT diagram, while (also) not easy to read, will show you how much crystal restructuring goes on for how much time the steel is held at temperature.
These diagrams were generated from thousands and thousands of tests, and verified over and over. Engineers (like me when I finish my degree) use these diagrams to show exactly how the crystal structure should be formed, and compare real world results to theoretical numbers... Then, we apply additional math to that material science.
You just have to figure out at which amount of recrystallization to quench. You also have to figure out if tempering cycles to allow some of the softer crystals to re-form will help the properties of your blade. You don't need the calculus, the explanations for FCC/BCC/HCP crystal structures, etc. like I will need.
Knowing this may help you predict where to harden your blades instead.
Nice job! Thanks.
Hi I bought a 3000-8000 grit double sided wet stone, it's my first time using a wet stone. As a beginner is it ok to start with or I need something else also? Please suggest.
11:20 digging the Alec Steele vibe of this music.
Are the bigger grain knives better at edge retention?
to look at grain structure. And dont be like all the a holes (well the sgow i guess ) that forge their pass blades way hot in the 3 burner kilns
Was the oil at the same temperature in every quench?
Whats the piece of music used during the temperature test?
what about the different times the metals were taken out of the chamber, the door opening and closing could cause temperature fluctuations which might cause the changes in the 1st knives that you were testing since those knives were already processed prior to you reheating and then testing them out.
Excelent video ! One question did you tried a soak period smaller than 5 minutes ? I would normally use only 2 minutes, but I do not work with 1095.
I subbed man, I love these tests
Keep it up
Couple question Alex. So for your oven would you put any and all metal/knives in the oven at 1200 then let the temp raise to its set temp(seems like your go to is 1475) and then let it soak for 5 minutes? Or would you put them in at 1475 and then let it soak for 5 minutes?
Second question is when you were heating them before with your little torch stove and would quench once they are past magnetic and then heat for a little longer how does the time compare there?
They were put in at 1200 and ramped to 1475 then soaked. When i was using a forge i was using 1080 which doesn't need to be soaked. So it was heat to non magnetic, then about 30 seconds more (depending on blade size) and quench. 1095 is a different beast 😀
@@OUTDOORS55 Ok sounds good. Dont know much about steels yet so just gaining info. Thanks for thr reply!
Ya know there's actually a whole profession based on the science of quenching. They do the math for temperature, what kind of oil, how long, etc. just to get a perfect quench. It's mainly used in very important machinery and equipment. For example NASA uses people to get the parts for space craft absolutely perfect.
Yes ive talked with a couple of them. The consensus is they are not sure what is going on. The only way to tell would be to use more specialized equipment to examine the results.
Would your oil temp raising as you went down the line affect anything?
Oil temp? I know very little about the harding other than you take really hot metal and put in a liquid to cool it. One thing I do know is if you put a hot object in to a liquid the liquid heats up. How much the liquid will heat up depends on the amount of liquid, the temp and size of the object. Could the oil have gotten to hot to properly quench the steel?
The knives were definitely large enough to raise the temperature of the oil by quite a bit. I don't know if the oil had enough time to cool back down in between or if the temp raised enough to make a difference.
So "soaked/quenched at 5 minutes" is referring to it being heated up for 5 minutes?. And does that 5 minutes start as soon as you put it in the oven, or once the metal reaches that temperature?
The last three test pieces were normalized right? The ones prior with the significant growth in grain structure were not. So maybe that’s what caused the inconsistency. When not normalized the temp and soak time can play a major role in grain structure growth but when normalized the steel may not be affected so significantly by temp and soak time. I’m just reaching but not sure myself. Do you think that can be the case or am I way off?
Possibly...I find it odd that there was consistent grain growth as the time increased though. Im not sure to tell you the truth. What I do know is that im going to normalize every blade.
OUTDOORS55 yea definitely can’t hurt... I mean unless you burn yourself. Thanks for the videos man. You’re an awesome knife maker.
maybe you should add tabs on the knives that you can just break off and test without ruining the knife
Great info! Thanks for sharing.
the answer to the question of why the third knife was weaker is that the other two knives being quenched changed the temperature of the bath enough to quench the blade improperly. I don't know why you had to break the knives to figure that out, it's just common sense.
The oil temperatures were monitored.
Does the water temperature make a difference?
420 °F is 215.556 °C and 400 °F is 204.444 °C if anyone was wondering.
why? because patreon's like us shelled out the big bucks to watch you do so. I think that pretty much sums it up
Did you consider the fact that temperature of oil is raising after each quench? or it doesn't affect the structure of metal?
All the ones you normalized had good grain structure, the ones you didn't , Didn't. Normalizing is key, even on stock removal knives, to get a good blade. Most Smiths know this already, from trial and error.