How does bearing steel make a good knife?

50 to 100 50 to 100 50 to 100 and 50 to 100. hey guys welcome back to the shop today I've got a tip of the day video for you or maybe it's more of a just as a discussion we'll sit down and talk about some steel for a minute something that I like to do geek out on steel a little bit so if you like that this is the video for you I just got done forging a batch a big batch of knives this week and I'm now rough grinding we're grinding about half of them so taking a little break from that stand in the grinder for extended periods of time kind of got stiff you know so you gotta take a little break here and there so I wanted to talk about 50 to 100 steel because I like talking about steel and 50 to 100 steel is my main my go-to steel it's the steel that I make most of my Knives Out of now and have for a while now I still use a few different other Steels depending on the project that I'm doing but by and large most of my knives are 50 to 100 and you know I came to that conclusion after uh years several years you know of sort of research and trying a few different Steels and thinking about you know what it is that I was trying to get from a steel you know the best deal that I could get for what I'm doing so we'll talk about that but 50 to 100 steel it was developed as a bearing steel about a hundred years ago so for example here's a bearing right here this is a big truck bearing and you know I thought this would be a neat idea it's a neat object lesson I guess you could say uh something like that you know what what is it about this bearing here the steel that's in this bearing that would make a good knife how does this compare to for example this nice little santoku Style blade that I'm working on you know not really the same right pretty dissimilar and yet the same steel uh works well for both applications so why is that so it's an opportunity to look at the characteristics of 50 to 100 steel so think about a bearing it's got load it has pressure weight you know however you want to say it on this assembly there's an outer ring which I don't have your your rollers or ball bearings as the case may be and then the inner ring and all of those main parts are made from 50 to 100 typically this retainer here is just mild steel I guess and it's not really part of the discussion so you've got weight on this assembly it has to be able to resist deformation like for example these rollers right here you can't have them squishing uh it has to be that's a technical term no squishing and so it has to be able to resist deformation that's strength that's a characteristic of Steel that you need for this particular application secondly you have a surface contact and although these are around it's rolling it's all greased up you know the the friction is diminished as much as possible that's sort of the whole point here nevertheless you do have surface contact and take into consideration the longevity of the part in hundreds of thousands of rotations and wear resistance becomes an important characteristic for this steel you don't want it to wear out quickly comparative to the job that it's put under and then finally as far as I can see it you need something that is uh tough enough you know you don't you don't want this steel here any of these parts to be displaying brittle Behavior you don't want it to crack fractured chip Etc under this weight or this load that it that it's on this part and so it needs to be you have a certain level of toughness and so 50 to 100 Steel meets all of those requirements to build this part and it does so also this is important in a cost effective and uh efficient manner you know so if there was something better for this application it I don't think they would be still using the same steel for over 100 years if there was something better and it it's also not just how the steel performs but because conceivably you can come up with a steel that does all of those things better but you know how much is that going to cost like once you get into your high alloy Steals and all these different things you're looking at a pretty significant cost increase and so that's a consideration in industry but it's also a consideration for the bladesmith So within certain parameters 5200 steel is the best option and also you know it comes to ease of manufacture that's another big consideration for industry and uh the bladesmith you know whether how how easy it is to forge how easy it is to heat treat and all this kind of stuff so we'll talk about that in a second here but so the next question is how does 50 to 100 steal as a steel meet those characteristics how does it do it well first of all 5200 steel is a high carbon steel it has about one percent carbon in it and as blade seals go that's less than some but higher than I would say most at at least when it comes to high carbon Steels once you get into your high alloy and your stainless Steels those typically have considerable amount more of carbon that's not really part of our discussion because we're talking about Steels that you can forge Steels that you can sharpen easily and steals a hold an excellent Edge under a given task so it has a high carbon content that's necessary you know up to at least about point six percent carbon is necessary to reach a level of hardness in my understanding that would be applicable to an application like this and then beyond point seven seven percent carbon this deal isn't able to uh precipitate carbides with the excess carbon and that is very important for abrasion resistance basically very tiny hard uh particles within the steel Matrix of the steel that resist abrasion or wear so that's two two uh that high carbon content is kind of knocks out two of those requirements then as far as toughness uh there's about one and a half percent chromium in this steel which really helps with the toughness and it also helps with some of those other things as well so let's talk about that first thing that the chromium does is it slows the well it helps with the heat tree process because it slows the necessary cooling initial cooling rate for hardening the steel you get a steel like 1095 for example it's not going to fully Harden or reach as full uh potential hardness unless it's cooled at a very fast rate initially and that chromium content in the 50 to 100 slows that process down to where you don't have to cool it as fast and it will still achieve maximum hardness so that's helpful when it comes to manufacture and it's also uh well it's helpful with that but it's just it's more foolproof I guess you can say it's hard to for one thing it's hard to cool steel that quickly and avoid a fracture or cracking and so that presents a lot of other problems so that allows you to cool it at a slower rate and achieve the hardness and therefore the strength that you want in the steel so additionally the chromium content helps regulate the amount of carbon that you're putting into Solutions because just as it slows things down it's part of the same process slowing down that carbon um movement so to speak within the steel and that helps regulate the amount of carbon that you're putting into solution because contrary to what you might think or what some people may say you do not want to put all of that one percent carbon into solution uh that that could lead to brittle Behavior and so the chromium helps with that and then finally the chromium does help keep the grain size down the grain structure small and that really helps with toughness as well so some several really good things that chromium content does and works together with that high carbon content to make a very in my experience very tough uh great steel that just holds an edge really well when it comes to the Knife application so talking about that how does a steel that performs well as a bearing steel apply to a knife so let's talk about that because all these characteristics that we just talked about and how that steel how the 52100 steel accomplishes that is very important for application in a knife if you have a knife here this one does not have an edge on it yet it's not even finished ground yet it's about halfway through the process but just imagine that it has an edge it's very thin this blade is ground fairly thin right now it's going to be a little bit thinner before I'm done and the edge is going to be very thin you know on this particular knife about 10 thousands behind the edge before I put a bevel on it 10 to 15 maybe that's going to vary depending on the knife and what it's used for but whatever the case is you've got a thin cross section on your blade and as you're cutting something that thin cross section is uh is coming against comparatively very per square inch is a very high pressure so I'm trying to say it needs to be able to resist deformation just like in the case of a high pressure application such as this has to be able to resist deformation as soon as you get deformation you get a Dull Knife whether it's you know just crushing flattening The Edge or rolling it over in any of those cases you lose your Edge you have a Dull Knife so that strength that resists resistance to deformation or hardness is important in the 5200 steel fills that bill nicely so secondly we have abrasion resistance so anytime you're cutting something whether it's a piece of rope or twine or a cardboard box or vegetables or meat or anything to one degree or another has it has an abrasive effect on the edge of the steel and remember again you know it's a very thin cross section and so that that abrasive effect in essentially is accentuated or Amplified because of that very very minimal surface area that you're contacting and so if you know it's going to have a greater effect on it you could scrape the spite of this knife on something all day long and it's not really going to change it much but everything has an abrasive effect to one degree or another on that knife blade and so the carbides that are in this Steel because of the high carbon content allow for greater abrasion resistance than most of your high carbon Steels that you'll find in knives and that is another reason why 5200 steel is great for a blade steel and then finally the toughness aspect that we just talked about a minute ago with the bearing stuff when it comes to the edge toughness is also important as well because you don't want the edge to chip break fracture or exhibit brittle behavior in in any manner once you do that you've broken off that sharp on the microscopic level you've been you've broken off the sharp uh Edge on your knife and you you have a Dull Knife so toughness is also very important on the microscopic Edge level so those three applications or three characteristics necessary for this application are also very important for this application as well I find that interesting and fund it to fun to think about and you know beyond that when they develop a steel and I've never developed a steal or anything like that I don't do that but I I use Steels and understanding how the components of a steel uh the composition lends itself to particular applications is important and then beyond that you have to know how to heat treat it properly you can take a really good steel heat treat it improperly and end up with a really lousy knife or tool or whatever so that's important uh but I'm not going to get into the heat treat process or anything like that today if that's something that you would like to see I have been thinking about doing an in-depth video on how I heat treat 50 to 100 steel and it is all based on practical application and performance of the knife and that includes all these three characteristics that we talked about as well as you know overall toughness of the blade which also plays into the blade design and things like that but that's something you'd like to see throw it in the comments and we might be able to do that in the future here I really like 5200 steel it's a great steel for you know probably 90 of the blades that I make now uh the the majority of them at least and uh you know it's got some just like any steel it's got some different characteristics or idiosyncrasies with it that you have to learn about and learn how to work with it but it's uh it's great stuff and I really I like it so I thought I'd talk about it talk about it so anyway that's kind of it for today guys um you know just trying to crank out crank out the product and um got some got a great idea for a video coming up next week and uh if you're regular to the channel you know you'll stay tuned for that because there's some different ideas that we have that are fun and I think this one's I think this one's going to be good as well so is there anything else to say so better stop talking as always appreciate you guys watching and we will see you on the next video

Channel: Fire Creek Forge

Views: 12,168

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Id: _8U16wDE-yA

Length: 14min 51sec (891 seconds)

Published: Fri Oct 07 2022