TOOLMAKERS DUNK, BLACKSMITHS DIP! HOW DO YOU QUENCH? Heat treatment of steels, hardening steels

hi and welcome back to the shop today's video well is going to be about heat treatment and more than nine it's going to be mainly about Quincy but before we get into that I'd like to say that I haven't been producing too much lately but it has been exciting around here actually I've had a little accident and well here's one of the bruises that I can actually show you what was that I said well unbeknown to me I was enrolled in some gliding courses and well I guess I didn't do that well because my taking off was great my flight was amazing it's the landing that was difficult now I have no video of the accident but I do have a few pictures and I can talk you through it so here's where I took off this section here was the section that I flew over and well here's where I landed and I can tell you a stone staircases are very hard but nothing was broken amazingly enough just a lot of cuts and bruises and contusions I guess we could say now the question that I received the one that pushes me to produce this short video what was a question that came in or left-field now I get a lot of questions about heat treatment and well we have some good videos about that and I get a lot of questions about materials and well we also have a lot of good videos about that but today's question sort of mixes it all together and the question is why new tool makers don't submerge the part that they're quenching and leave it submerged while moving it around whereas a blacksmith dips this part twice sometimes three times to cool it down why the difference see this both are quenching well the difference has a lot to do with carbon you may or may not know that steel isn't iron and well the iron isn't steel there is however iron in the steel but there's no steel in iron iron is an element so it is at its simplest just items of iron where in steel is a mix it has to at least be a mix of iron and carbon so if we have iron and carbon mixed in accurate proportions and we give that part a shape by foraging or whatnot well we've produced steel and if I take some iron heat it up and give it a shape by hammering forging or what now I've produced a piece of iron it won't change now if I quench a piece of iron since there is no carbon in it well it cannot be hardened so iron is as hard as it's going to be it can't be made harder by heat treatment whereas steel can be usually or in many cases I should say hardened by heat treatment what do we mean by many cases now there is low medium and high carbon steels whereas the iron well is just the iron but don't be fooled the iron is often in presence of carbons when it's produced in a blast furnace for example well there is carbon present in the furnace and while the iron can absorb a certain amount of it and while iron that the blacksmith would use can contain some carbon and may be enough to be heat treatable know what I mean by that is we have three levels of carbon steels are divided in that way we have low medium and high content carbons so high carbon steel medium carbon steel and low carbon steel as a general rule and although it's not Bingbing at the low and high there's alignment between the two that's very accurate Dolph general rule low carbon steel cannot be hardened by heat treatment medium carbon steel can meet hardened by heat treatment to a medium hardness so somewhere around forty to let's say 55 Rockwell C now if you don't know what this is all about and it could be the case you may want to head back a little bit and go take a look at the series of videos that cover the heat treatment it's probably pretty boring stuff but it's important stuff so medium carbon steel can be hardened to a medium level and well high carbon steel often called a tool steel well can be hardened to a high degree of hardness we're talking here sixty to seventy-five Rockwell somewhere around there Rockwell C okay great stuff from and high carbon Steel's what does that represent so zero two point three percent carbon in the mix will be considered low carbon steel 0.32 somewhere around point six million carbon steel will save fifty five point five five instead of point six somewhere around there and well let's say a point six to a build 0.83 and now I'm going by memory here but I think point 83% of carbon in iron is the point of saturation of carbon in iron any more than that and you get free carbon in the mix so let's say four point six to 0.8 three we have high carbon steels now what the blacksmith is using is iron with a lot of experience the blacksmith can judge maybe even without knowing exactly what's going on chemically speaking but can judge about the amount of carbon that he has in presence of the iron and maybe it's just borderline a medium carbon steel or maybe it's somewhere in the high end of the low carbon steels and that means that he could harden it by clenching but be careful there's hardening and surface and there's hardening in depth what I've just described whether it be steel low medium or high plain carbon Steel's or the iron that is mixed with carbon the blacksmith may well you in both cases it is difficult to harden that those materials through and through let's say I had a one inch by one inch block of steel medium carbon steel that sake plain carbon steel just iron and carbon well if I had that I would get a hardness on the outside I might even managed to get a sixteenth to an eighth of an inch of depth but I won't be getting much more than that and why is that to harden a piece of steel we need to heat it up to within its critical range of temperature again in the heat treatment videos we talked about it and then we have to cool it down quickly but how quickly we cooled it down has a lot to do with what's in the plain carbon steel so when all that we have is iron and carbon well we have to cool that down very quickly to get it to harden so if I have a thick massive part weight i clench apart it cools from the inside towards the center now the inside will cool quite quickly but the middle is going to take a long time to cool and it just won't harden so plain carbon Steel's have that problem and the blacksmith has that problem and that is why they dip instead of a dunk in a few seconds now how can we get through and through hardened steel else that will use four punches four tools for all kinds of things well they are called alloy carbon steels and while they had where they produce these materials different alloying elements that change the properties of the steel now if you're looking for a steel that will cleanse readily and harden through but totally through the part that even if it is massive and thick where you're going to be adding elements that make the part easier to Clint now a 4140 alloy carbon steel is a medium carbon steel the 41 tells me that but it is an alloy steel that contains elements that really help the quenching so when I quench a part of 43:41 40-story well I can expect that it's going to get hard through and through it doesn't have to cool down this quickly to stay in that hardened state okay plain carbon Steel's have to cool down fast iron with carbon that the blacksmith may use has to cool down very fast why well because the blacksmiths mix of iron and carbon very often only really has carbon on its outer surface so it really has to cool them quickly if we're gonna get anything that resembles a hardened part so that is why we get the double dip why well when the blacksmith dips and pulls them it's generally accompanied by a twitch which is a technical term but a quick of steam and that steam is an indication of a liquid in this case water going from a liquid state to a gas and to do that transition well the material water has to absorb vast vast amounts of energy that means that when we dip and pull out and let the steam fly were actually cooling the part very quickly if we see that the steam is starting to lower I quickly dip it and pull it a second time to keep that drawing of energy from the part going and it's fastest rate now once we've reached a certain temperature it doesn't have to be completely cold but anywhere under any of those 1,100 degrees but we'll play it safe and say 800 degrees Fahrenheit after that you don't have to cool it anymore it's hard or it's soft but if it did hardened it's gonna stay that way even if the part is quite hot it's not hot enough to change that state so that is why the blacksmith doubled it he needs her she needs to cool the part as quickly as possible because of the quantities of iron that is in the part now we said that zero two point three percent of iron of carbon in steel well is a low carbon steel and they're generally considered to not be hardened of all however even if I have a point two percent carbon so clearly in the low carbon Steel's of them if I can cool it down quick enough I will get a certain amount of hardness but I will not get very much credit penetration is that clear now why do tool makers not do that as a general rule the faster you cool down apart the more deformation that part is going suffer during that cooling process now if I'm a blacksmith and I get a certain number of thousandth of an inch let's say deformation on the part that I'm producing compares the word isn't that type of accurate I mean a blacksmith works very accurately I'm almost amazed at what these people can do but it's not the same type of precision that the tool maker would need we have less skill but more accurate ways of producing things so if I want to produce a hardened punch for a punch and I'd let's say and I want that punch to be accurate within a few thousandths of an inch well I'm gonna have to grind it after I heat treated we've heard all of those that in our videos but I wanted to deform the less possible because I want the grind at the least possible to finish it I'm gonna rough the part out leaving a certain amount on it and we saw that in our one two three block project videos and then I'm gonna heat treat it and then I'm going to go to the grinding and grind it to its final very very accurate dimensions once it's harden but I do want the least amount of deformation possible so I use an alloy carbon steel if I have again I'll come back with a 41 40 I could have chosen old one steel as well oil hardening class 1 or a tool steel the acquainting in oil actually slows down the cooling process and that is not a problem with steels like how many seals that are made Arden easily because even if I cooled down slower than water well I still get a hard part I mean when you Clancy it's either hard or it's not heart you can't heart in half you can get better penetration the hard or soft won't change so let's say I clench the cool down slowly in oil well I will get less deformation on complex parts plus an added bonus the parts that the toolmaker produce is often has internal angles and while these parts are prone to cracking the faster it cools the more prone to cracking tool steel will be so if I can quench it in oil and cool it down slowly well that is a good thing for cracking as well so we see there's a lot of advantages that the plain carbon Steel's just don't have toe that is the reason why so why doesn't the toolmaker dunk well you see this lovely face you see these eyebrows and eyelashes and a total lack of hair up here but that lack of hair isn't due to a large fire or explosion oil explosion now think of it if we and we have examples of many projects that we've produced videos on where you see the night dunk when i dunk a part in oil I want to keep it dunked now heat treatment oil as a flashpoint of somewhere around 600 650 degrees I forget somewhere around there and that means that it will spontaneously ignite that temper trip great as long as they keep that temperature below that it won't ignite my part let's go back to our 4140 needs to be around fifteen hundred and fifty degrees before i dunk it in the oil that means I'm gonna get a fire not really there has to be air in presence for there to be a fire it's a rapid oxidization basically so if I dumped the part in oil and keep it well under the surface of the oil the part may be very hot but there is no oxygen in there we will not get an explosive remember I am using specialized heat treatment oils don't do this with any other type of oil it is very very dangerous okay that being said I keep it well under the surface now if I buy pure lack of knowledge and this is where terrible accidents happen if I dump and pull down like the blacksmith's does well I would have oil on the surface of that part and I would have a part that's around 1500 degrees or salt that has oil and oxygen available now 1500 degrees and you can count 6 12 18 is not very far from three times the flashpoint of the oil of reusing and that means what that means poof that means major flames that means a big big problem so we never want to pull her part out of the oil and we're using the oil because our parts have to maintain accuracy and the high carbon skills even the medium Carmen seals are prone cracking the blacksmith doesn't have these problems his main preoccupation is to cool that part down as quickly as possible so then polenta steam amounts of energy coming out of the part as quickly as possible that's not what tool makers do the last thing but I don't think the questions about about the cleansing itself well is why once we cleanse doing those around know when you dunk Quinn's dunk your part in the large quantity you don't do this in just a little bit neither a big barrel or a large container we're talking several gallons here when we dunk it in there to cleanse the part oftentimes you'll see me moving in the flow figure 8 movement so the park moves around in I never pull it out until it's cool enough not to ignite so somewhere below 600 degrees but I will move it around why is that you'll see if you dunk it in there's going to be a certain amount of gas that oil is going to turn to gas the liquid to gas and it's going to envelope the park envelop and look and bail up the part and well it actually creates a barrier here between the cool oil we're going to have a liquid to solid transferable and especially if i dunk the park a little at an angle and one part gets more in the liquid faster or has less accumulation of gases at its surface there we have deformation because it's not even if I don't as straight as possible and then I move slowly into figure eight well I'm ensuring that the French oil comes in contact with all the surface of the part as evenly as possible so there you go I hope that this is cleared up some of the mysteries surrounding quenching remember cleansing and water is never dangerous I mean you can't start a fire in the bucket of water we agreed but quenching in oil is very dangerous do it outside if you don't have a proper cleansing area that is concedes for that do look outside use only a cleansing oil and do it only if you really understand what's going on we're full face protection and full body protection when you do it because if I pull your skirts it could get ugly degrees very quickly so till we meet again have fun be safe I hope you manage to stay awake for the whole video and well happy machine [Music]

Channel: THATLAZYMACHINIST

Views: 4,423

Rating: 4.9876161 out of 5

Keywords: heat treatment of steels, hardening steel, quenching steel, machine shop, machining parts, how to harden steel, how to heat treat steel, marc lecuyer, thatlazymachinist, how to machine metal parts, free online machine shop lessons, how to make things

Id: LeJaqAZ_C3w

Length: 24min 38sec (1478 seconds)

Published: Thu Jun 25 2020