I learned a similar technique from Machinery's Handbook. The carbon material was combined with rock salt. The salt when it liquefies allows freer movement of the carbon, and creates a reducing atmosphere minimizing oxidation. Hold temp at 1800* 6-8 hours, reduce temp to 1400* for 2 hours. Remove from furnace and quench parts in water. Follow up with a draw temper at 400* for 1-2 hours. It's best if you can suspend your parts in the salt/carbon solution. I was making specialty hammers for metal smithing which needed case hardening. These already had eyes for attaching handles and I was able to suspend using baling wire. Heavier parts could be suspended using slings of several strands of baling wire. This whole process allows for more even, deeper penetration throughout the parts being treated. I never did a Rockwell test, I do know that once treated, then mirror polished my hammer faces never marred or deformed.
Seems like it would give you a very nice, thick case (100 thou or more). Not that common in industry. I do many "shallow case" jobs requiring only 1 hour at 1700 to meet the spec. I've only seen a few very deep case jobs. Thanks for sharing that old recipe.
When you just pass material science course without knowing anything at all such as pearlite and its brothers and you suddenly find a video in which you learn a whole topic in just 8 minutes. I’m being in love with this channel!
So true... education expects you to be interrested enough to find out more on your own i guess... but it lacks the part where it teaches you to do just that, available, free and fun ways to quickly go deeper and uncover much more interesting things full of other more interesting things...
Congratulations gentlemen, As an “old” retired toolmaker, I have machined quite a lot of tool steels, that were “sent out”, and did some in house O-1. I have never done any case hardening. Your presentation is very informative, and presented in a clear and concise manner.
The song in the beginning gave me inner peace and taught me how to find calmness. I have been emotionally healed and cannot express my gratitude enough for this gift. I come here just for it atleast a few times a week. Thank you.
I learned this method in trade school in the mid-70's. It is quite effective, and a good way for apprentices to gain an understanding of metallurgy and heat treating, Very appropriate for making one's own tools without the expense of commercial tool steels. We were also using, along with the powdered charcoal, barium carbonate as a catalyst to speed up the process (As I remember, 10-20% CaCO3). Basically, what is happening is that carbon monoxide is generated to fill the sealed box, which gives the carbon to dissolve into the steel. More time gives deeper penetration. The early Mauser bolt action receivers and bolts were treated this way, as well as other makes of firearms. Even cast iron can be pack hardened.
Incredibly informative. You clearly explained the pearlite --> austenite --> martinsite process -- far better than any material science book I've ever looked at.
Love the Lindberg furnace. Chicago. Vacuum heat treat changed all that warping and carbon. Well presented video. Tool Maker of 40 years. Father knew ALL the heat treat methods. Good luck and make some big money with your knowledge.
Thank you for the very informative video. I just finished a couple of small forming dies that are subjected to fairly heavy loads. They turned out very well and solved a problem for me. The only variation to your procedure was to add 10% by weight of sodium carbonate to act as catalyst while carburizing. I was most impressed with your choice of carbon and it worked. We used Kasenit in high school and I understand it is no longer available. There is another product available but i will be using Kingsford charcoal in the future. Thanks again and keep up the good work.
Great video. The animations helped me learn about the grain structures. All this time I thought it was called "Case Hardening" because the metal was put in a case. Now I know better.
I did the same project in college but sadly got poor results as the carbon powder we had to use was too well used already and the carbon was leached out. Your crushed briquets are a better idea. Almost 60 Rockwell to 1/16"? Amazing! Well done.
Looks like you are using a nitriding furnace for your temper furnace. For this type of tempering, I use a toaster oven from WalMart. Plugs into a standard wall socket.
1018 if hardened will run about 40RC, throughout. any tempering at all will, obviously, make it quite soft (250f draw is around 25RC, if memory serves). the "as hardened" condition isn't file hard on the surface like the case part would be, but would still produce quite serviceable blocks for all but the most abusive of alloys. don't do "mild steel" the disservice of dismissal from heat treatment unless carburized. it just won't get too hard to deform without fracturing. it also is limited in depth of hardness to about 1 inch wall thickness to produce uniform hardness. without the manganese content, it would be half that for wall thickness, and an "as hardened" condition of 30RC or so. the manganese encourages the carbon to remain in solution, so the cooling has a chance to "freeze" thicker parts before carbides drop out. but, within those limits, you can get 50 ksi working parts out of 1018, and single cycle heat treat to boot, lol
One of the issues with pack carburizing is the problem of getting the steel to pick up the carbon that the charcoal lets off. Commercial carburizing compound, like what you might buy at McMaster Carr, has additives to promote carbon absorption. I think one of those additives is calcium carbonate, but I am not sure. The advantage here is to absorb more carbon, therefore add more carbon per unit of time, giving you a deeper (thicker) effective case depth, a topic which you do not cover. With commercial carburizing compound, you get a harder, deeper case that responds better to quenching, ensuring maximum hardness and a thicker case. The minor disadvantage is the tendency to produce a "white" outer case layer, which is commercially too brittle, requiring a "diffusion" temperature cycle slightly below 1700F for a few hours before slow cooling. Also, you should be quenching in a fast oil (possibly a used motor oil for the poor man) instead of water to minimize the chance of cracking, which will ruin your part, requiring you to start all over machining another piece of steel. The reason why you are quenching in water is because the carbon from the charcoal briquettes was not being absorbed as fast as it could, requiring a more severe (water) quench to achieve a high hardness, at the risk of a higher probability of cracking the steel. Also, keep in mind to temper the steel immediately after quenching because some quench cracks are time-delayed, and will not occur if the steel is already tempered.
I did! I have heard that case hardening can also be done by quenching in oil after taking the parts out of the first furnace treatment. This is for a decorative finish on the steel.
Hey guys, I have a quick question, if you carburize a mild steel knife blade fro a couple of hours, in order to succesfully finish the process does it need to be enmediatly quenched or air cooling it works just fine?? After the carburization I intend to clay quench it to make a hamon that's why I don't want to quench it after carburizing it and before apliying the clay.
I did this with a machine shop class in 1973, we all made a pair of parallels. I remember as if it where last week. I still use mine weekly. We dumped the whole lot still red hot into a tank of water.
hi ! thank you very much for the video, I would like ask, do you know what is the phase of the midde of the of the steel which wasn't cabunized? thanks
Is there a difference between using raw chunk charcoal vs briquettes that have fillers and lighter fluid mixed in? Or are those also technically (hydro)carbon sources and work the same?
Great video. Do you do anything to burn off the oxygen in the box with anything wood chips etc? Or have you tried using foil? I have a few jobs to carburize and could use a few pointers. It it 8" Ø by 1" thick. Your thoughts please? Cheers from Canada.
Excellent video. Thank you for taking the time to make it interesting, factual, and succinct. I have subscribed because I like the efficient way you put these videos together. Great work all-around. Much appreciated. I like your sense of humor as well.
The carbon doesnt dissolve into the steel... it diffuses interstitially in between the crystalline structure of the iron atoms. Carbon atoms are a lot smaller relative to the iron atoms, and can therefore 'slide' in between those structures, resulting in a harder surface
Very informative video. Thanks for sharing. What would be its HRC after carburizing (before quenching)? Also, will you lose the high-carbon property of a case hardened steel when you anneal it repeatedly?
I liked the video very informative. I do have a question however. What purpose does case hardening have? I'm curious the benefits of case hardening over just starting with a more appropriate steel? Would a 1080 or a comparable steel be less effort? It just seems like a lot of hassle when you could just buy a higher carbon steel, or alloy steel.
Case hardening gives a hard exterior and soft interior. The harder, the more brittle, the softer the more ductile. This gives you a pice that has a hard wear resistance on the outside and a softer inside that can absorb more shock. This makes an overall pice that may end up with surface cracks if shocked (like being dropped) and will not totally shater. The piece will remain usefull.
Jeremiah Huntley Yes that makes sense. However when I make a hammer out of say 1045 or a 4140 I harden it then temper it, it makes it so when there is an impact It will not chip or shatter. There are a steels out there such as an s7 or d2 or maybe even a 5160 that you can make incredibly hard and scratch resistant that will not damage even when dropped on a hard surface when heat treated correctly. That are much easier to accomplish than the case hardening process.
Jeremiah Huntley Yes but what looks to be like a 16+ hour process as a oppose to a maybe 3 hour process with the right steel, would negate the cost. Also for the purpose in which these items are used the process seems to be a bit overkill. Every machinist I have ever met guards these tools with their life as to not damage them. I really don't see some one using it as a hammer. Just to be clear my curiosity is purely educational. My intent is not to be a troll.
¿How thick does this work to? I ask because International Militry Antiques makes a surfaced hardened grabenpanzer that was actually tested by InRange and provided "good" protection, but not against most of the rifles they tested. It's been speculated that through hardening might fix it.
Might be a silly question, but if you're machining, rather than forging, the case hardened steel, how do you get the hardened metal to stay on the outside of the part? What's the point of hardening the surface if you're cutting off parts of the surface to make a tool?
Emil Sorensen: The only finishing these blocks will receive is from a very light surface grinding, to get the surface true, this will leave .030" of hard surface, you cannot machine the blocks when they have been quenched, the whole point of case hardening, as explained in the video, is to achieve a glass hard wear proof surface, with a strong malleable core, this is just perfect for things like gears, or parts subjected to impact stress that need to be wear resistant.
The material removal is just enough to true the part since it may not be flat and square after the quench. Carehardening, as used in firearms for example, seldom exceeds .005" depth since if deeper than this any thin sections may through harden and become brittle. Its possible to do deeper levels on blocks and other parts without thin sections and thus more can be taken off to true the parts and still retain the very hard slick surface. HOWEVER. The part must be intentionally made over size to allow grinding to proper dimension.
Almost as hard to finishing watching as an adult film. Amazing work gents. Really wanna fix up the C on an old J Stevens 12 GA Pap used as a "tractor gun, idk where to start, I can cold blue the rest.
Two questions. Could you form mild steel into a raw billet so it sucks carbon all the way through? And can it be case hardened multiple times to get a good blade worthy steel like 1095?
If oxygen was allowed in the box the carbon (charcoal) would ignite and burn off thus creating a hell of a lot of smoke and depriving the steel of the carbon it needs to create the case hardening.
To color case harden the steel, I think you have to take the box out while it's still at maximum temperature, turn it over, and dump the parts straight into the water to quench them before they're exposed to oxygen.
Hey, Ethan, We're primarily concerned with case hardening as a way to improve the wear resistance of steel, as opposed to improving its aesthetic qualities. So, case coloring is not a topic on which we can offer much information. That said, here are a few points from our research on the topic: - Case coloring is less a product of carbon diffusion into hot steel than it is a product of impurities in the carburizing compound interacting with the hot steel in a sealed environment. Common recipes for effective case coloring compounds include bone charcoal, leather, and a host of other carbonaceous materials with various impurities which produce unique coloring effects. - The carburizing box and the clay/mortar applied to its seams create a hermetically-sealed environment which also appears to be critical. Moreover, case colored parts should be quenched directly after carburizing without allowing the parts to interact with ambient atmosphere. Most practitioners elect to dump the contents of the box directly into the quenching medium. - You can case color steel at temperatures below the temperatures required for case hardening. And case coloring will eventually wear off and the treatment will need to be reapplied. On the other hand, the surface hardening effects of the case hardening process are essentially permanent. - The coloring effects of the case coloring process are notoriously unpredictable. The patterns and colors produced from one part to the next are highly variable and sometimes the coloring effect doesn't occur at all. This one-of-a-kind nature of case colored parts adds to their allure.
Generally the colors you see when you heat steel is a result of the oxidation of the steel as a result of tempering. When the steel air cools after tempering it will take on a specific color determined by the temperature it was tempered at. At the 400f used in this video the cooled tempered piece should have taken on a straw color. The hotter the temperature the more blue it will be, however tempering at higher temperature will result in a softer steel.
Thanks! My friend works at a place that makes transmissions for airplanes and helicopters and he brought me some scrap pieces of 9310. Pretty sweet steel if I can case-harden it properly.
If you don't want to case harden this type of block, you can machine the blocks out of tool steel, which will still require a quench and temper to approach the hardness of the blocks in the video. From a practical standpoint, machining the blocks out of 4130, 4140, 4340 alloy steels will also work (after a quench and temper, without carburizing) (water quench 4130, oil quench 4140, 4340). They will be a lower hardness, but you will rarely, if ever be machining anything harder. By avoiding carburizing, you will bypass the problems a newbie will encounter. However, avoid stamping them to avoid a starting point for quench cracks.
I thought case hardening was a very thin layer. I didn't realise you could get really useful thicknesses of case using just charcoal. Not something I need to do now but I'm definitely going to file it away in the mental locker. Thanks very much!
Lynda Anthony: Yes providing you can achieve and hold the temperature, there is no need to maintain temperature for many hours, if you reduce the time to 2 hours you will just get a thinner case hardness, adequate for most applications, but these blocks are to be surface ground, so the maximum case was required.
Different furnaces and kilns are specialized for different tasks. But at the end of the day, heat is heat. If you have something that can generate the right amount of heat for the length of time required, you can make it work.
Der Kommentator your axe head is likely all high carbon steel, so it can easily be hardened. It likely already is. If you lost the hardness from overheating, you can do a similar heating then quenching and tempering, you probably only need to heat treat the first inch or so of the cutting edge.
Question. Does anyone know where I might see someone using the method of Wayland? where he fed his geese iron nails then collected the leavings and forged a sword worthy of a great king I read that some smiths in Africa do something similar. I am probably guessing that would get you asked to leave youtube.
Quick question - why not just use 1050 or another 10 series steel with a higher carbon content and then just through harden it? I’m asking out if sheer ignorance. I have no idea LoL
For all that is holy please get better charcoal or make your own for case hardening I prefer bone charcoal myself. For better colors and just because its more traditional...I am being nit picky and prefer case Color hardening
Color Case Hardening is only used on Surfaces that are not going to be Ground afterwards, otherwise the Beautiful Color Case Hardened Surface will be completely Ground Off. The 1”-2”-3” Blocks they just Carborized, Hardened, and Tempered, will be Finish Ground, on all Surfaces, to Tolerances that are unobtainable by Finishing a Part to Size, Bone Color Case Hardening, and left “as Hardened.” I hope this has clarified to you, why the Beautiful Bone Case Hardening a Process is not appropriate for these Parts.
@@shelliesman7552 the fact remains that there are better charcoals available. Briquettes contain a rather large percentage binder and filler. Real charcoal does not contain any binder or filler. I wouldn't want these mystery materials leaching into my product that I spent so much time and energy to produce. But to each, their own. I guess.
Can I know the preparation of charcoal . What are the ingredients are mixed with charcoal. Is it possible to got the hardness 0f 45HRC on the non magnetic steel like AiSi304
Ooh ooh, I can answer this one. *Short answer*: Having a lot of carbon in steel allows for really cool structural formations that make the metal really hard, but another important factor is grain size. Cooling it quickly by quenching it gives a smaller grain size which makes the metal harder. *Long answer*: So basically, metal atoms like to arrange into neat crystal patterns, but if you get the metal hot enough, the atoms jiggle around too much to stay in nice crystals. When you lower the temperature a bit, they will start to slowly form back into their crystal structures, but the crystallization will start in multiple places. This means that multiple crystals will form inside the metal. Thousands, in fact. Once these crystals (called grains) run into each other, they stop growing for a bit because even though they have the same structure, they aren't oriented the same way. This creates discontinuity in its structure at the boundaries. If you cool the metal slowly, atoms can diffuse across these grain boundaries causing the many small grains to condense into a smaller number of larger grains. But if you cool the metal quickly, say by quenching it, the grains stay very small. Now when you apply stress to a metal, the sheets of atoms that make up the grains can start to slip, like spreading out a deck of cards. However, because the sheets are oriented differently between grains, the slippage is slowed down by grain boundaries. Having a smaller grain size means having a ton of grain boundaries, making the metal very hard. This is why quenching steel (or any metal really) makes it harder.
hey.. I'm no expert at all on the topic...have a couple of questions if anyone can help me with them... it seems like an annealing or stress relief that you are doing by letting it cool in the crucible in the furnace prior to removing and then bringing the part back up to critical temperature before quenching. I wonder if bringing it back through to critical temperature outside of the crucible destroys or reduces the effectiveness of the case hardening... does it increase through hardness by encouraging some of the case layer to migrate deeper?... does it allow carbon to precipitate out of solution in any greater measure by being again exposed to critical temperature and potential for scaling?.. why not just dump the parts strait out of the crucible, at temp for austenitic phase, into the quenchant? Thanks
The point of the first heat was to add carbon to the steel not harden it, but you are right about just dumping it in water right after the first heat, as long as it is at critical temperature it should work. However reheating it should not hurt it, as long as you do not leave it at critical temperature for too long it will not have a negative effect. And reheating later will also allow a normalizing cycle to take place and create a finer grain structure.
The reason it was left to cool in the oven is because this was done in a school class. I'm sure nobody was around 8 hours later to quench it. So they put it in, set the timer and came back the next day and reheated and quenched. it could have easily been quenched at the end of the carburizing cycle, if someone had been around to do so. Either way works just fine. Sometimes you have to do workarounds to fit things into a schedule.
I used case harden from time to time in the last shop I worked. But I never thought about being able to use charcoal rickets. We all ways used a product called Kasenit.
Hi Adam, thanks for the video, I think this is the most comprehensive video about case hardening in youtube. I want to ask a question about this process, will the process alter the dimension of the part? I'm going to make a precision part using mild steel, with tight dimension tolerance, the part will be about 60mm in diameter and tolerance of 0.5um.
Guns N Glory butimous is great bcuz it smokes easily , and is usually 60% carbon . Anthracite coal (not to be confused with anthracite iron) , is 98% carbon the best , but it takes a higher heat to release
Word of advise - turn the box over so it acts as a bell and then you will not need to seal it. Also briquette has lime in it - use lighter lumped charcoal - pulverized.
I learned a similar technique from Machinery's Handbook. The carbon material was combined with rock salt. The salt when it liquefies allows freer movement of the carbon, and creates a reducing atmosphere minimizing oxidation. Hold temp at 1800* 6-8 hours, reduce temp to 1400* for 2 hours. Remove from furnace and quench parts in water. Follow up with a draw temper at 400* for 1-2 hours. It's best if you can suspend your parts in the salt/carbon solution. I was making specialty hammers for metal smithing which needed case hardening. These already had eyes for attaching handles and I was able to suspend using baling wire. Heavier parts could be suspended using slings of several strands of baling wire. This whole process allows for more even, deeper penetration throughout the parts being treated. I never did a Rockwell test, I do know that once treated, then mirror polished my hammer faces never marred or deformed.
Seems like it would give you a very nice, thick case (100 thou or more). Not that common in industry. I do many "shallow case" jobs requiring only 1 hour at 1700 to meet the spec. I've only seen a few very deep case jobs. Thanks for sharing that old recipe.
When you just pass material science course without knowing anything at all such as pearlite and its brothers and you suddenly find a video in which you learn a whole topic in just 8 minutes.
I’m being in love with this channel!
No shit. I should have watched this video in school! So information dense.
So true... education expects you to be interrested enough to find out more on your own i guess... but it lacks the part where it teaches you to do just that, available, free and fun ways to quickly go deeper and uncover much more interesting things full of other more interesting things...
Congratulations gentlemen,
As an “old” retired toolmaker, I have machined quite a lot of tool steels, that were “sent out”, and did some in house O-1. I have never done any case hardening. Your presentation is very informative, and presented in a clear and concise manner.
The song in the beginning gave me inner peace and taught me how to find calmness. I have been emotionally healed and cannot express my gratitude enough for this gift. I come here just for it atleast a few times a week. Thank you.
I kinda got irritated by the music !
I hardened my blocks by telling them their mama never loved them and life is a big fight!
@@emptychristbuddha but they hard af bro
Don’t you be sayin’ bout they Mama! Hmm huh!
I sprinkled viagra on my blocks
Aaaaaaahahahahhahahahahah
Yeah that should do it. That's pretty much my story and I dont even have real emotions anymore .
I learned this method in trade school in the mid-70's. It is quite effective, and a good way for apprentices to gain an understanding of metallurgy and heat treating, Very appropriate for making one's own tools without the expense of commercial tool steels. We were also using, along with the powdered charcoal, barium carbonate as a catalyst to speed up the process (As I remember, 10-20% CaCO3). Basically, what is happening is that carbon monoxide is generated to fill the sealed box, which gives the carbon to dissolve into the steel. More time gives deeper penetration. The early Mauser bolt action receivers and bolts were treated this way, as well as other makes of firearms. Even cast iron can be pack hardened.
I've been using tools treated in this manner for forty years and just learned what it actually is. Thank you
can you case harden 300 series stainless?
Incredibly informative. You clearly explained the pearlite --> austenite --> martinsite process -- far better than any material science book I've ever looked at.
We did this in High School. I was lucky. Forever grateful to Mr.Earl
Hammerston.
Love the Lindberg furnace. Chicago. Vacuum heat treat changed all that warping and carbon. Well presented video. Tool Maker of 40 years. Father knew ALL the heat treat methods. Good luck and make some big money with your knowledge.
Thank you for the very informative video. I just finished a couple of small forming dies that are subjected to fairly heavy loads. They turned out very well and solved a problem for me. The only variation to your procedure was to add 10% by weight of sodium carbonate to act as catalyst while carburizing.
I was most impressed with your choice of carbon and it worked. We used Kasenit in high school and I understand it is no longer available. There is another product available but i will be using Kingsford charcoal in the future.
Thanks again and keep up the good work.
Great video. The animations helped me learn about the grain structures. All this time I thought it was called "Case Hardening" because the metal was put in a case. Now I know better.
I agree with Terry Davis.Best explanation of the metallurgy involved that I have yet seen.Well done and thanks for sharing.
YOU GUYS IS THE INTELLIGENT OF THE CHEMISTRY AND THE MACHINE
Adam, your channel is straight quality!
I did the same project in college but sadly got poor results as the carbon powder we had to use was too well used already and the carbon was leached out. Your crushed briquets are a better idea. Almost 60 Rockwell to 1/16"? Amazing! Well done.
Looks like you are using a nitriding furnace for your temper furnace. For this type of tempering, I use a toaster oven from WalMart. Plugs into a standard wall socket.
1018 if hardened will run about 40RC, throughout. any tempering at all will, obviously, make it quite soft (250f draw is around 25RC, if memory serves). the "as hardened" condition isn't file hard on the surface like the case part would be, but would still produce quite serviceable blocks for all but the most abusive of alloys. don't do "mild steel" the disservice of dismissal from heat treatment unless carburized. it just won't get too hard to deform without fracturing. it also is limited in depth of hardness to about 1 inch wall thickness to produce uniform hardness. without the manganese content, it would be half that for wall thickness, and an "as hardened" condition of 30RC or so. the manganese encourages the carbon to remain in solution, so the cooling has a chance to "freeze" thicker parts before carbides drop out. but, within those limits, you can get 50 ksi working parts out of 1018, and single cycle heat treat to boot, lol
What quench temp and quench medium? I have heard of people hardening mild steel with the proper quench medium.
Thanks
I'm
One of the issues with pack carburizing is the problem of getting the steel to pick up the carbon that the charcoal lets off. Commercial carburizing compound, like what you might buy at McMaster Carr, has additives to promote carbon absorption. I think one of those additives is calcium carbonate, but I am not sure. The advantage here is to absorb more carbon, therefore add more carbon per unit of time, giving you a deeper (thicker) effective case depth, a topic which you do not cover. With commercial carburizing compound, you get a harder, deeper case that responds better to quenching, ensuring maximum hardness and a thicker case. The minor disadvantage is the tendency to produce a "white" outer case layer, which is commercially too brittle, requiring a "diffusion" temperature cycle slightly below 1700F for a few hours before slow cooling. Also, you should be quenching in a fast oil (possibly a used motor oil for the poor man) instead of water to minimize the chance of cracking, which will ruin your part, requiring you to start all over machining another piece of steel. The reason why you are quenching in water is because the carbon from the charcoal briquettes was not being absorbed as fast as it could, requiring a more severe (water) quench to achieve a high hardness, at the risk of a higher probability of cracking the steel. Also, keep in mind to temper the steel immediately after quenching because some quench cracks are time-delayed, and will not occur if the steel is already tempered.
I did! I have heard that case hardening can also be done by quenching in oil after taking the parts out of the first furnace treatment. This is for a decorative finish on the steel.
can you plzz make a video on Nitriding?
Nitriding is very intresting, I would also like to see how gaseous Amoniac is handled in this process.
Hey guys, I have a quick question, if you carburize a mild steel knife blade fro a couple of hours, in order to succesfully finish the process does it need to be enmediatly quenched or air cooling it works just fine??
After the carburization I intend to clay quench it to make a hamon that's why I don't want to quench it after carburizing it and before apliying the clay.
This is absolutely the first time i've subbed to a channel off of the the first 30 seconds of a video... Damn.
So if you only used 1/8 in. Thick mold steel would the part be hardened all the way through?
Potentially. Check out Clickspring's channel for some good videos on case hardening small parts.
Great video! what does the treatment time depend on?
have you tried to see how deep the carbon infusion on the box after years of usage?
so how do you get the scar pattern?
I did this with a machine shop class in 1973, we all made a pair of parallels. I remember as if it where last week. I still use mine weekly. We dumped the whole lot still red hot into a tank of water.
I've been making knives for years and this is the best explanation of grain structure and how hardening works that I've ever heard.
hi ! thank you very much for the video, I would like ask, do you know what is the phase of the midde of the of the steel which wasn't cabunized? thanks
Is there a difference between using raw chunk charcoal vs briquettes that have fillers and lighter fluid mixed in? Or are those also technically (hydro)carbon sources and work the same?
you guys got a video on your hardness machine thingy there, that American Chain and Cable, Wilson Zerominder ???
How did you calculate the time & temp vs the penetration of the carbon? Are there graphs or I have to use the Fick's Second Law?
How long does it take for the oven to reach that temperature?
Great video. Do you do anything to burn off the oxygen in the box with anything wood chips etc? Or have you tried using foil? I have a few jobs to carburize and could use a few pointers. It it 8" Ø by 1" thick. Your thoughts please? Cheers from Canada.
You need to make more of these videos! They're incredible!
Excellent video. Thank you for taking the time to make it interesting, factual, and succinct. I have subscribed because I like the efficient way you put these videos together. Great work all-around. Much appreciated. I like your sense of humor as well.
Great video. One of the best explanations of the metallurgy that I've seen. Thanks for the effort put into the comment responses.
I'm a subscriber.
This is GREAT for new people in machining, whether machinists or inspectors. The right amounts of practical knowledge and science.
The carbon doesnt dissolve into the steel... it diffuses interstitially in between the crystalline structure of the iron atoms. Carbon atoms are a lot smaller relative to the iron atoms, and can therefore 'slide' in between those structures, resulting in a harder surface
Very informative video. Thanks for sharing.
What would be its HRC after carburizing (before quenching)?
Also, will you lose the high-carbon property of a case hardened steel when you anneal it repeatedly?
Patrick Tan it would be dead soft without quenching. Yes each anneal process would diffuse the carbon in the surface case
nicely done i was a general machinist for 35 years and never run across this process
I liked the video very informative. I do have a question however. What purpose does case hardening have? I'm curious the benefits of case hardening over just starting with a more appropriate steel? Would a 1080 or a comparable steel be less effort? It just seems like a lot of hassle when you could just buy a higher carbon steel, or alloy steel.
Case hardening gives a hard exterior and soft interior. The harder, the more brittle, the softer the more ductile. This gives you a pice that has a hard wear resistance on the outside and a softer inside that can absorb more shock. This makes an overall pice that may end up with surface cracks if shocked (like being dropped) and will not totally shater. The piece will remain usefull.
Jeremiah Huntley Yes that makes sense. However when I make a hammer out of say 1045 or a 4140 I harden it then temper it, it makes it so when there is an impact It will not chip or shatter. There are a steels out there such as an s7 or d2 or maybe even a 5160 that you can make incredibly hard and scratch resistant that will not damage even when dropped on a hard surface when heat treated correctly. That are much easier to accomplish than the case hardening process.
It just comes down to price, purpose, and needs.
Jeremiah Huntley Yes but what looks to be like a 16+ hour process as a oppose to a maybe 3 hour process with the right steel, would negate the cost. Also for the purpose in which these items are used the process seems to be a bit overkill. Every machinist I have ever met guards these tools with their life as to not damage them. I really don't see some one using it as a hammer.
Just to be clear my curiosity is purely educational. My intent is not to be a troll.
is the difference between annealing and tempering that you use higher temperatures for annealing ? as in red hot vs blue hot for tempering ?
¿How thick does this work to? I ask because International Militry Antiques makes a surfaced hardened grabenpanzer that was actually tested by InRange and provided "good" protection, but not against most of the rifles they tested. It's been speculated that through hardening might fix it.
Might be a silly question, but if you're machining, rather than forging, the case hardened steel, how do you get the hardened metal to stay on the outside of the part? What's the point of hardening the surface if you're cutting off parts of the surface to make a tool?
Emil Sorensen: The only finishing these blocks will receive is from a very light surface grinding, to get the surface true, this will leave .030" of hard surface, you cannot machine the blocks when they have been quenched, the whole point of case hardening, as explained in the video, is to achieve a glass hard wear proof surface, with a strong malleable core, this is just perfect for things like gears, or parts subjected to impact stress that need to be wear resistant.
The material removal is just enough to true the part since it may not be flat and square after the quench. Carehardening, as used in firearms for example, seldom exceeds .005" depth since if deeper than this any thin sections may through harden and become brittle. Its possible to do deeper levels on blocks and other parts without thin sections and thus more can be taken off to true the parts and still retain the very hard slick surface. HOWEVER. The part must be intentionally made over size to allow grinding to proper dimension.
can you do nitrocarburizing in a similar manner?
At 2:17 the guy puts the clay on the box but doesn't cover the seam. Why is that?
Almost as hard to finishing watching as an adult film. Amazing work gents. Really wanna fix up the C on an old J Stevens 12 GA Pap used as a "tractor gun, idk where to start, I can cold blue the rest.
Does it now have that oily, colorful finish?
Two questions. Could you form mild steel into a raw billet so it sucks carbon all the way through? And can it be case hardened multiple times to get a good blade worthy steel like 1095?
Might be fun to relate what you did the iron-carbon phase diagram and TTT diagram.
Awesome video! What would happen if you didn't hinder air flow with the cement and alow oxygen in during the carborizing process.
If oxygen was allowed in the box the carbon (charcoal) would ignite and burn off thus creating a hell of a lot of smoke and depriving the steel of the carbon it needs to create the case hardening.
Best treatment of the topic I have seen to date. Now maybe do a Shop built Heat heat treat oven? Compete with controls thermocouples and wiring?
Wish there were videos like this when I did my machinist apprenticeship
A newcomer to your channel. I appreciate the clarity in which you explain your subject matter, bravo and keep up the good work.
I worked in commercial heat treat for 30 years, cool video 👍🏼
Will you grind the case hardening if you finish grind the blocks and the hardening only goes down 1/16th of an inch?
Excellent video. Thanks for taking the time to film and edit it and of course for positing it for our benefit. Keep up the good work! -Migs
does this process prevent corrosion of steel?
So how does case hardening work when you get that rainbow patter on the steel?
To color case harden the steel, I think you have to take the box out while it's still at maximum temperature, turn it over, and dump the parts straight into the water to quench them before they're exposed to oxygen.
Hey, Ethan,
We're primarily concerned with case hardening as a way to improve the wear resistance of steel, as opposed to improving its aesthetic qualities. So, case coloring is not a topic on which we can offer much information.
That said, here are a few points from our research on the topic:
- Case coloring is less a product of carbon diffusion into hot steel than it is a product of impurities in the carburizing compound interacting with the hot steel in a sealed environment. Common recipes for effective case coloring compounds include bone charcoal, leather, and a host of other carbonaceous materials with various impurities which produce unique coloring effects.
- The carburizing box and the clay/mortar applied to its seams create a hermetically-sealed environment which also appears to be critical. Moreover, case colored parts should be quenched directly after carburizing without allowing the parts to interact with ambient atmosphere. Most practitioners elect to dump the contents of the box directly into the quenching medium.
- You can case color steel at temperatures below the temperatures required for case hardening. And case coloring will eventually wear off and the treatment will need to be reapplied. On the other hand, the surface hardening effects of the case hardening process are essentially permanent.
- The coloring effects of the case coloring process are notoriously unpredictable. The patterns and colors produced from one part to the next are highly variable and sometimes the coloring effect doesn't occur at all. This one-of-a-kind nature of case colored parts adds to their allure.
Thanks for the in-depth response, very helpful! Thanks!
Generally the colors you see when you heat steel is a result of the oxidation of the steel as a result of tempering. When the steel air cools after tempering it will take on a specific color determined by the temperature it was tempered at. At the 400f used in this video the cooled tempered piece should have taken on a straw color. The hotter the temperature the more blue it will be, however tempering at higher temperature will result in a softer steel.
Use bone meal charcoal, also when quenching, use areated water to quinch. It will healp with the colors
how deep dose this case Harding go because I seen milling marks on them and they will need to be surface grinded after words ?
Can you link the next video about, "finishing on the surface grinder" in the description?
Your voice and cadence is perfect for spoken word songs
That music is horrible. I'm trying to hear the narration, why compete with yourself ?
Go away
Thanks! My friend works at a place that makes transmissions for airplanes and helicopters and he brought me some scrap pieces of 9310. Pretty sweet steel if I can case-harden it properly.
If you don't want to case harden this type of block, you can machine the blocks out of tool steel, which will still require a quench and temper to approach the hardness of the blocks in the video. From a practical standpoint, machining the blocks out of 4130, 4140, 4340 alloy steels will also work (after a quench and temper, without carburizing) (water quench 4130, oil quench 4140, 4340). They will be a lower hardness, but you will rarely, if ever be machining anything harder. By avoiding carburizing, you will bypass the problems a newbie will encounter. However, avoid stamping them to avoid a starting point for quench cracks.
Holy cow guys, excellent presentation.
I wonder if this is the same process used on some old 19th century gun parts.
I thought case hardening was a very thin layer. I didn't realise you could get really useful thicknesses of case using just charcoal.
Not something I need to do now but I'm definitely going to file it away in the mental locker.
Thanks very much!
thanks I need a shop to make some harden wood chipper Blades/knifes
would they also work in a kiln such as what is used for ceramic art?
Lynda Anthony: Yes providing you can achieve and hold the temperature, there is no need to maintain temperature for many hours, if you reduce the time to 2 hours you will just get a thinner case hardness, adequate for most applications, but these blocks are to be surface ground, so the maximum case was required.
Different furnaces and kilns are specialized for different tasks. But at the end of the day, heat is heat. If you have something that can generate the right amount of heat for the length of time required, you can make it work.
What is the hardness of 1030 if it is Case harden by 0.002 to 0.005 inch deep?
Can i use this for an axe head? I know, it would only make for a thin layer of "hardness". Or what would you recommend?
Der Kommentator your axe head is likely all high carbon steel, so it can easily be hardened. It likely already is. If you lost the hardness from overheating, you can do a similar heating then quenching and tempering, you probably only need to heat treat the first inch or so of the cutting edge.
I hope you know there are additives to that brand of charcoal. Its not just charcoal.
Now that's old school!!! Haven't seen that in years!!! 😊
Would this work for knives?
It can be done, gun parts too
Question. Does anyone know where I might see someone using the method of Wayland? where he fed his geese iron nails then collected the leavings and forged a sword worthy of a great king I read that some smiths in Africa do something similar. I am probably guessing that would get you asked to leave youtube.
Excellent explanation, and showing. Thanks
Quick question - why not just use 1050 or another 10 series steel with a higher carbon content and then just through harden it? I’m asking out if sheer ignorance. I have no idea LoL
some parts preform better with a soft center it helps it from breaking a thru hard part may just snap into
What's through hardening???? The Q&T process???
For all that is holy please get better charcoal or make your own for case hardening I prefer bone charcoal myself. For better colors and just because its more traditional...I am being nit picky and prefer case Color hardening
Color Case Hardening is only used on Surfaces that are not going to be Ground afterwards, otherwise the Beautiful Color Case Hardened Surface will be completely Ground Off.
The 1”-2”-3” Blocks they just Carborized, Hardened, and Tempered, will be Finish Ground, on all Surfaces, to Tolerances that are unobtainable by Finishing a Part to Size, Bone Color Case Hardening, and left “as Hardened.”
I hope this has clarified to you, why the Beautiful Bone Case Hardening a Process is not appropriate for these Parts.
@@shelliesman7552 the fact remains that there are better charcoals available. Briquettes contain a rather large percentage binder and filler. Real charcoal does not contain any binder or filler. I wouldn't want these mystery materials leaching into my product that I spent so much time and energy to produce. But to each, their own. I guess.
Just wondering if this process is Carbon Neutral :P ?
How do I make it a blue gem?
Back in the day, I used to use a acetylene touch burning dirty and let the carbon soot saturate the piece as it was heated
Can I know the preparation of charcoal . What are the ingredients are mixed with charcoal. Is it possible to got the hardness 0f 45HRC on the non magnetic steel like AiSi304
Charcoal mixed with charcoal. Ask the manufacturer of the charcoal what's in it. It will vary. Nobody uses the same recipe.
Why did you quench the material after case hardening?
Is it really required. Can you please explain?
Ooh ooh, I can answer this one.
*Short answer*:
Having a lot of carbon in steel allows for really cool structural formations that make the metal really hard, but another important factor is grain size. Cooling it quickly by quenching it gives a smaller grain size which makes the metal harder.
*Long answer*:
So basically, metal atoms like to arrange into neat crystal patterns, but if you get the metal hot enough, the atoms jiggle around too much to stay in nice crystals. When you lower the temperature a bit, they will start to slowly form back into their crystal structures, but the crystallization will start in multiple places. This means that multiple crystals will form inside the metal. Thousands, in fact. Once these crystals (called grains) run into each other, they stop growing for a bit because even though they have the same structure, they aren't oriented the same way. This creates discontinuity in its structure at the boundaries. If you cool the metal slowly, atoms can diffuse across these grain boundaries causing the many small grains to condense into a smaller number of larger grains. But if you cool the metal quickly, say by quenching it, the grains stay very small. Now when you apply stress to a metal, the sheets of atoms that make up the grains can start to slip, like spreading out a deck of cards. However, because the sheets are oriented differently between grains, the slippage is slowed down by grain boundaries. Having a smaller grain size means having a ton of grain boundaries, making the metal very hard. This is why quenching steel (or any metal really) makes it harder.
hey.. I'm no expert at all on the topic...have a couple of questions if anyone can help me with them... it seems like an annealing or stress relief that you are doing by letting it cool in the crucible in the furnace prior to removing and then bringing the part back up to critical temperature before quenching.
I wonder if bringing it back through to critical temperature outside of the crucible destroys or reduces the effectiveness of the case hardening... does it increase through hardness by encouraging some of the case layer to migrate deeper?... does it allow carbon to precipitate out of solution in any greater measure by being again exposed to critical temperature and potential for scaling?.. why not just dump the parts strait out of the crucible, at temp for austenitic phase, into the quenchant?
Thanks
The point of the first heat was to add carbon to the steel not harden it, but you are right about just dumping it in water right after the first heat, as long as it is at critical temperature it should work. However reheating it should not hurt it, as long as you do not leave it at critical temperature for too long it will not have a negative effect. And reheating later will also allow a normalizing cycle to take place and create a finer grain structure.
The reason it was left to cool in the oven is because this was done in a school class. I'm sure nobody was around 8 hours later to quench it. So they put it in, set the timer and came back the next day and reheated and quenched. it could have easily been quenched at the end of the carburizing cycle, if someone had been around to do so. Either way works just fine. Sometimes you have to do workarounds to fit things into a schedule.
Thank you, I've learned a lot from you than my school...
I used case harden from time to time in the last shop I worked. But I never thought about being able to use charcoal rickets. We all ways used a product called Kasenit.
hi adam, please do upload more videos on different types of hardening,grinding etc and more of bearings
Hi Adam, thanks for the video, I think this is the most comprehensive video about case hardening in youtube. I want to ask a question about this process, will the process alter the dimension of the part? I'm going to make a precision part using mild steel, with tight dimension tolerance, the part will be about 60mm in diameter and tolerance of 0.5um.
do some video on testing like you have done in this video
ya didn't show the final pic of it ?
One big ooops : kingsford coals are very very high in limestone , getting in the way of ur carbon saturation
Guns N Glory yes : full circle hardwood lump briquettes, or good ol Virginia mined coal
Guns N Glory butimous is great bcuz it smokes easily , and is usually 60% carbon . Anthracite coal (not to be confused with anthracite iron) , is 98% carbon the best , but it takes a higher heat to release
Guns N Glory google blacksmith coal , but make sure its anthracite or bituminous
Guns N Glory or check wiki: metallurgical coal
Heyyyyy usa coal !!
Word of advise - turn the box over so it acts as a bell and then you will not need to seal it. Also briquette has lime in it - use lighter lumped charcoal - pulverized.
Doesn't look totally airtight. Does this matter?
EXCELLENT explanation and covering diverse topics
Can mild steel knives be case-hardened effectively
hideouse blob just buy good tool steel such as D-2
what's the equation of carburizing?
Thanks - excellent informational video. I especially apprecieated the concise but complete presentation of the process along with the science!