The ONE and ONLY THING you need to get the best grain size
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- čas přidán 30. 04. 2022
- All you need is a temperature control! Our favourite Heat Treat Pro, Graham Clarke, shows us the best equipment to use when doing heat treatment for your blades! In this knife making video, Graham also talks about quenching oils, the different types, and which ones you should use! Get your knife to form martensite first time, every time!
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I've watched three videos in this series and they are excellent. I'm a fitter and turner by trade so I had to learn a bit about metallurgy. I've also made a few knives. I wish I'd had Graham as a tutor with his confident, common-sense approach. If he's willing, I'd like to nominate him to become prime minister.
thousand and one blacksmith/bladesmithing channels should be watching this guy....fantastic.
Cheers Talabavin Rohan!
I have watched many videos over the years but NO ONE explains things as well as you Sir (clear, simple to understand, complete explanation of topic ). Thank You so much!
Cheers Steve for the lovely feedback! Graham is an absolutely amazing chap and I am happy to have had the opportunity to share Graham’s knowledge with you all! Thanks for watching!
- Vinz
Thanks Steve - it's nice to know someone has been listening 🤣🤣🤣🤣🤣🤣
Got. Damn. I'm an amateur smith and I wish I could just download this guys brain into my own head. He's like an endless well of stuff I wondered about.
Hi Witten. Graham’s mind is available for download. Please check our website for more info 😂🤣
Thanks for watching and taking time to comment!
- Vinz
Please tell my missus that!!!
I run a double burner gas forge and i rigged up a high temperature k-type thermocouple to a high temp digital guage. I can raise to my high temperatures, turn back a little holding temperatures for soak. Once i upgraded to my forge with that i started getting great repeatable results
Great comparison to a cup of tea. If the water isn’t hot enough the sugar doesn’t fully dissolve…same for the alloys in the steel
Thank you for your amazing videos and all the knowledge you’re giving us. Means the world
Cheers Luke! Glad to hear you’re enjoying the content we put out!
More good advice. Thank you, Mr. Clarke.
Hi again JHC C. We got one more Graham video before we close the series.
Thanks for watching again!
Hi Mr Clarke.. I'm just a kid (32 hah) that reads books (mainly verhoeven and suchlike) to learn this stuff as I do it for a hobby and I most certainly will not sit here and try to call myself a metallurgst aha but there is a few things that I would.. add to this that I know you know about obviously and please don't read this the wrong way over the internet (we all know how that can go), I highly respect your experience and knowledge way above mine - but I personally try to explain this stuff in one way similar to how you do the alpha to gamma to martensite formation etc, but in a way that people that don't know all the physics and chemistry things that are rather important they don't "understand" this. I try to explain things like, when heat treating, although most conventional books I've read say that most carbide is in solution within like 5 minutes which it is, they don't mention that say a longer hold is going to spherodize the carbides or -- (I know you do simple steels I do high alloy PM stock removal cause I'm a science nut although I can respect the art part just as well) -- say like.. tempering as soon as possible after austenitizing is beneficial.. cryo has to be thought of like heat treating and even during tempering you're creating a new Ms so, like me personally, I cryo in between tempers to make sure that I hit the finish temp. I'm not sure exactly how beneficial this kind of information is to what you teach however so I totally understand leaving it out we can't include everything in a video. BTW, I'd pay you to talk to you about some metallurgy stuff that a guy who lives 5 minutes from me who I'm sure you know, Larrin Thomas, me and him do not get along and I've been trying to do a modified CPM MPL-1 26Cr PM alloy for kitchen knives but. The market is limited for that one, but nonetheless I could offer you full use of JMatPro if you don't already have it. It's a pretty neat little thermodynamic calculating computer program. I'm legitimately asking to pay him for his brain and he apparently hates me so much (I can come off critical over text), it's a long story not meant for here. I'm sure you are very busy but I wouldn't mind asking the same question! Hahaha. Sorry man I had to!
I thought about doing this CZcams thing myself but I have realized how little knife makers actually know how to heat treat and.. they don't care. I'm the type that does this for the science behind it. I'd like to play around with a forge (I have) but the limited alloy choices make me sad inside.
Anywho, not to be critical of anything just commenting. I wish you the best of luck with everything there sir and of course you have my respect as there's no reason not to if I have to type that out.
- Jason Ward
is there a podcast or so with Mr Clark?
i could listen to that for hours.
and nice to know that my chosen quenching oil is perfect for my preferred steels.
although I'm definitely not doing my pre heattreat cycles the way he advises us to do 😂
Hi 3co nice to see you back! I (literally) sit hours on hours with Graham and the dude never stops sharing great info! I’m happy to have been able to share this series with you all!
I'm banned from talking too much at our bladesmithing classes by my son & grandson for fear of comatosing our clients 🤣🤣🤣🤣🤣🤣
@@clarkeknives4159 i volunteer for the absolute overload of information.
where do i sign up?
@@clarkeknives4159 I will fly out to the UK just for a class so you can talk my ear off
I have always used canola oil heated to 120 degrees C for quench. This method has worked well for me with W2 steel, and recycled leaf spring for my knives.
Lol, I think you mean 120 F
W stands for.. water. Water quenching. O2 would be oil quench. If your blades are thin enough maybe you can get away with it but you might not be getting full hardness. A2 is air tempering just to complete the set.
More Graham!! Thanks!
Yup yup yup we got more coming for sure! Have you seen his other vids here on the channel too?
So educational , thank you much!
You’re very welcome mate and nice to see see you again!
Great content...I'm learning a heap over here. Thank you.
Hi Get Smart you’re very welcome!
Great content. What a wealth of knowledge. Thanks for posting.
Cheers Wes! Happy to see you watching again! We got one more video with Mr. Clarke so stay tuned!
Wonderful video. Thanks for the info, well done 👍
Glad it was helpful!
Brilliant video..all the best Lincoln 👍🤙
Cheers Lincoln 🍻🍻🍻
Best video about the subject!
Cheers Proton Plasticos! I appreciate you taking time to leave some feedback!
Howdy from across the pond. Another very interesting knowledge filled video! Thank you very much.🤝
Hi Mel you’re welcome!
Fantastic
Thanks for watching!
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@UK Bladeshow , thanks for this I was wondering which one was worth having
For the smith on a tight budget, what would you say to one of the slightly less expensive models from the same company that might not have quite as high a temperature range? For example, the model you recommend goes up to 1800°C, while the one that goes up to 1500°C is only about 2/3 the price. How necessary is it to have that extra 300°, especially considering that anything above 1600°C is probably liquid anyway?
It all depends on your use and what steels you work with but for myself, I do not need anything over 1500degC so I would save myself some money and take that. I hope that helps!
@@UKBladeshow It does; thank you.
More of the heat treat godfather!
Hello Love All! We have one last Graham video coming up don’t you worry! See you again in the next video!
Better than a magnet is salt melting on your steel. The one option i didnt see mentioned was templisticks.
Hi Graham, greetings from a cool but sunny South Africa, if I am not mistaken that "Magnetic Point" is called the Curie Point Temperature, some books say 767°C others I think round it off to 770°C.
Hi Victor thanks for sharing! Not sure if you were aware but Graham lived most of his professional life in South Africa too! Thanks for your comment!
@@UKBladeshow yes, Graham and I met a few times at Neels van den Berg's Black Dragon Forge, still in the original forge. Graham and I actually did an Introduction to Bladesmithing Course together. I don't know why but I seem to think his wife was a diplomat? Back to my statement, that was more of an interrogatory question/statement to see if Graham you affirm or correct me.
Good videos as always. I agree identifying the colors from the chart and matching to the hot steel takes practice. And it is a deteriorating skill. During my apprenticehsip as a tool and die maker I was quite good at it now not anymore.
Small parts we heated up in an open flame and I remeber one or two steels where you could see the structure change. It looked like a shadow moving over the surface. For a couple of weeks I have temparature controlled kiln.
One question I have, what is the emissivity you have set your pyrometer to?
I too would like to know what is the emissivity you have set your pyrometer to.
Mr. Clark, thank you very much for taking the time and sharing your knowledge with all of us. I really appreciate it. I was wondering about differential hardening with W2 steel. Water quenching is said to have the best hamons, is there an oil that will produce as nice of a hamon as a water quench?
Depends where you are from. Parks50 or durixol v35. Durixol is fester.
What really determines a good hamon is the carbon content. Above 0.7% works and the higher the better so W2 should work well. It'll probably harden up OK in a fast oil as we only use thin sections for blades.
@@clarkeknives4159 Thank you for responding and for the information.
Thanks for raising a good question sankojin. I hope you enjoyed the video!
I did a lot of quenching into molten salts back in the 90's (developing spring steels) but there the aim was Bainite not Martensite. Molten Sodium Hydroxide is very good, as it has a high specific heat and also a very high infra-red transparency. The metallurgy lab (at Leeds University) were still using up old stocks of Whale Oil quenchant. The theory was that it worked well and that throwing it all away wouldn't help the wales at all, so they might as well use it up. Another very fast (and dangerous) quenchant I have heard of is mercury. Rivett lathes always advertised that their spindle bearings were "As hard as fire and mercury can make them"
Martempering is a fascinating thing. It's mostly useful for when you want a softer steel than you can temper without running into the enbrittlement between first and second tempering zones.. I suspect leaf springs of 5160 might do this to get it down to mid to low 50's while staying so tough. Normal heat tempering range of 375-450f will only get you something like 56-59 rockwell
Yes! Great Sunday morning!
I know he specializes in knives, but does he ever do anything on tools as well? Hammers and such? Either way great stuff.
to my mind knives are the most difficult to quench and he just covered block steels with the bubbling problem ...You should be able to take it form there that for a 1084 hammer you will need parks 50.
Hi both thanks for the feedback and the reply!
I also run a heat treatment service for farriers and blacksmiths who make their own tools, especially hotwork tool steels such as H13
Thanks you guys!
I'm currently using truck axles. I'm novice but growing fast, already pretty much full time thanks to help from the wife. I scrap to help supplement bill money. Anyway most truck axels from what I've gathered are 4140 steel and H13. I've made 3 and they hardened well in a hot water quench. I just want to learn all I can. I wish I would've had this drive ten years ago. Again big thanks🍻
I have a probe I stick in the forge. I watch the temp rise. Though I mostly do blacksmithing harden my tools.
Cheers Christopher!
I love Mr. Clarke’s presentations!
Perhaps i’ve missed it (i don't know for sure), but does Graham dabble with homemade wootz? I believe Pendray & Verhoeven’s work demonstrated that the carbide precipitation is accomplished with (1) certain quantities of alloying elements combined with (2) a series of normalizations (iirc). Graham mentioned not needing more than a single normalization when preparing to harden steel in another video, but he was not on the topic of wootz steel in that video
Wootz steel is not something I have, or ever intend to dabble in 😂😂😂😂 Wootz gave a unique combination of properties that worked for ancient sword makers. Even the worst steelmakers in todays world make steel that will do better.
Thanks for the comment WalledSonic!
@@clarkeknives4159true, but the patterning is very interesting and random, compared to intentionally folded Damascus, even though you can make stuff like damasteel with super steel properties.
What's wrong with using a IR temp gun to measure the temperature of your steel?.
I use the fast quench oil you sold when you were still in south africa.
Cheers Tim! Hope you enjoyed the video!
@@UKBladeshow I've been learning a lot from the ones on heat treatment.
Hi Tim, That oil should be nicely run-in by now. Think about changing it in another 20yrs.
8:25 what about using a pump to move the quench oil so you dont have these hot spots?
That is indeed a solution used in industry.
A pump is a bit overkill if you’re doing one knife at a time as a hobby when dunking it up and down by hand does the same thing as a pump would. A few 100s of kilos of expensive automotive parts, though, and an oil pump makes a lot of sense.
What are some things that have been salvaged from something else, and normalizing or a new one before we usually feel a better idea on a better practice?
The steel ceases to be magnetic at the Curie temperature.
Somewhat surprisingly it is purest coincidence that this is (almost) the same as the phase transition temperature.
Which is partly why, as you point out, a magnet can only ever be a guide.
A very interesting use of a carefully tailored Curie temperature is the Weller Magnastat (Or TCP) soldering irons. The tips cease to be magnetic at the set temperature, and that releases a magnetic relay and turns of the heater. This is how you can change the temperature setpoint by swapping tips.
The steel is EXACTLY nonmagnetic at the phase change because martensite isn't magnetic. Problem is, you might reach Curie before you fully convert if you heat it too quickly. Some steels are martensite at room temp and so not magnetic.
If you normalize the steel properly for pearlite, simple steels without carbides will dissolve very quickly into martensite and so you can quench the exact moment it loses magnetism. Look into Larrin's knife steel nerds website or CZcams channel for more information. I would normalize first even for stock removal so that you don't have to worry about holding temp for the quench
Martensite is magnetic. It's Austenite that is non-magnetic, but ferrite is also non-magnetic above the Curie temperature.
Is there a specific amount of quenchant for a specific mass of steel?
What emissivity should the IR Pyrometer be set to?
When do you change out your quench oil? Can X volume of oil quench Y mass? Can it be filtered/cleaned? Why is it a consumable item? My best guess is that the quenched metal is absorbing/removing some elements of the oil and not others?
Filtering out the crap that’ll acclimate will help the oil last longer.
Quenching oil will eventually need replacing when the additions used to break up the vapour layer are gone. They’re somewhat volatile so will burn off and react with the steel and stop working (it’s not so much the steel absorbing them but them reacting and not doing what they’re designed for). Using an oil too hot or too cold with also accelerate it’s degradation (see manufacturer’s recommended temp range).
For a hobby blade maker even old oil will likely be good enough. If you’re making safety critical parts for an aeroplane then you’d definitely need to keep a closer eye on oil quality and quench rates.
I'm planning to heat treating a 1075 knife today, I find that u should quench in oil, I think that is correct but I remember testing 1075 and I quenched it in water and the test piece held up fairly well
My heat treating did not happen because of issues I've decided to find a heat treating service
@@ThatOneOddGuy As a former contract heat treater, I approve of that decision.
A fairly fast oil should harden 1075. Water will definitely work but brings with it an increased risk of quench cracking and warping. The general rule is to quench as slowly as you can get away with while still getting a full transformation.
Given the quality of modern alloy carbon steels for knife making,does forging [properly] enhance or detract from from the finished product?
It depends…
Forging will generally give you better properties than an unforged steel. And going through the full process of normalising etc you’ll need to do with forging will give you a better carbide distribution compared to stock removal of an annealed steel. Forging also give you a bit more choice in blade shape and reduces the amount of material you need.
That said, stock removal from a decent steel properly heat treated might well be good enough for your requirements. The extra improvement and the added steps from forging (with the extra things that can go wrong) might not be worth it.
Do you recommend doing a normalizing apiece of stainless steel that was bought annealed and only stock removal methods done no hammering. Does the grain size still get a benefit from a normalizing cycle. I really like your videos you do a good giving lots of info with an easy way to understand what the steel is doing. Thanks for sharing 👍.
This is general advice that’ll work for most steels since I don’t know what stainless steel you’re using.
Stock removal will create some residual stress which might cause warping. A stress relieve cycle (done at a lower temp than normalising) would be recommended if you’ve taken a lot of material away. A normalising cycle will do a stress relieve as well.
You won’t have the ideal properties (grain size, carbide distribution etc etc) if you harden and temper directly from the annealed state but it might be good enough. If you’re sure you’ve got the hardening, quenching and tempering right and you’re still not getting what you want then you could look at normalising first.
Good quality steel bought annealed and used for stock removal will not need normalising.
I hope that answers your question directly from the horse's mouth Garet. Thanks for your comment!
What’s you opinion of using the visual aid of decalescence as a guide for forge heat treating
I had to look it up first…
I’ve not heard of it being used in practice. But my experience is with contract heat treatment where you really do need the accuracy of thermocouples.
Excellent channel. But I understand that forging, for example of wrenches, also creates a grain flow. If the grain size changes enough during heat treatment, is this grain flow pattern preserved?
The initial state of the grains will influence the hardening process so even a well heat treated cast won't have as good properties as a forged part. A full anneal will pretty much get rid of the effect though not totally.
It's not easy to see grain flow after hardening. There are industial standards for checking the prior austenite grain size but quite honestly they're not very reliable. Two equally trained people can get completely different results from the same sample.
The grain flow created by forging remains. Normalising may/will change the grain size but the flow pattern will still be there
@@clarkeknives4159 You're right of course. Seen plenty of macros to check grain flow myself. But i wasn't thinking of them for reasons best known to my subconscious...
Correction: it's not easy to see grain flow after hardening ^microscopically^. It's easy enough to see grain flow under the microscope before hardening but not after.
Hi. What type of steel at what HRC would you say it's best in terms of edge retention?
I do like sharpening knives and was obsessed with this a few years back, however now I have less time to sharpen them..
Could you please mention one stainless steel and one carbon steel?
Secondly, I would go for cpm rex 121 at 67 hrc - would that be silly?
A blanket statement on HRC isn’t going to be all that helpful, I’m afraid. It really will depend on the specific steel you’re using. In general, though, the higher the hardness the better a steel will resist the abrasive wear that will dull a blade.
There are basically two ways of achieving that hardness. The first is by how hard the martensite you generate is. Broadly speaking, the higher the carbon the harder the martensite. But… the higher the hardness the less ductility the steel will have. You can get the maximum hardness of a plain carbon steel right after quenching but it’ll be unusable because of how easily it’ll chip. So much so that you might not even be able to sharpen it without it chipping. You’ll need to balance hardness (and edge retention) with durability. The specific alloying can help shift how hard or tough the martensite is - nickel, for example, will generally increase the toughness of martensite.
The other main way is to include hard phases like carbides. That’s where most of the development of modern blades has gone. Those carbides can really ramp up the measured hardness while still having a relatively tough martensite. Most of the work has gone into fixing the size and distribution of the various carbides (and sometimes nitrides) in the steels. A lot of that is controlled by the steel making process itself so the same grade of steel from different manufacturers might not give the same results.
I’d advise scepticism on claims that X HRC is the best for knife making. 60 HRC can be way too high for a plain carbon steel to work properly while 68HRC can be just right for a steel with loads of well distributed Vanadium carbides in it. If you’re interested in a particular type of steel then I’m sure you can get good advice and help from the people that have used it before and recommendations from the steel maker.
Really interesting and useful as always. One thing I'm curious about though is never quenching knives into water. I understood that not only do water-quenching steels like W1 give the most active hamons but they also require at least the first part of the quench to be in water or they bend the wrong way. By the wrong way, I mean the tip bends down toward the edge not up away from the edge as you would expect on a katana or wakizashi. In my (extremely) limited experience, this is what happens. I have a 1095 tanto that has a passable hamon from oil quenching but the tip bent down not up. No clue why this would be the case but people like Walter Sorrells observe the same. Any ideas?
Water quenching is one of the best ways to start with one piece steel and get two out of the quench. Most contract heat treater won't touch it because of that. No one wants to tell a customer that the hard work they put into something has just been ruined.
Water is pretty much as fast a quenchant as you can get but it's also quite inconsistent. A general rule is to quench as slowly as you can get away with and as evenly as you can manage. Water is overkill on speed for most common steels (but is required for things like low/medium carbon unalloyed steels) and also not as consistent as oil.
I can go into why it causes problems if you'd like but it will need another long post.
I've been having a think about your knife bending towards the blade instead of away from it...
It's easy enough to explain why a katana would bend properly if done right. Martensite is a little less dense than pearlite so the hardened side of the blade will try to expand more than the back and cause the whole thing to curve.
Before speculating on the backwards curve - can you tell me if the tanto hardened up as you expected? Soft spine and hard blade?
Hi Tom, thanks for your continued thought on this one. I understood the different densities of martensite and pearlite would account for the normal curvature of the katana. I assume this also explains the "crispy bacon" wobbles that can occur in an edge if it is too thin when quenched.
The tanto hardened up as expected. The hamon is definitely there which I take to indicate there are different crystal structures on the edge and the spine. I'm struggling to think up any physical mechanism that would explain the reverse bend in the way differential density explains the normal bend.
@@RobanyBigjobz Hmmm... if it hadn't hardened properly I would have suggested the following:
Pearlite is a bit less dense than austenite. The blade side transformed first slightly pushing on the spine. Then followed by the thicker spine which would push the blade side further since there's simply more there. Ta-da! Backwards bend.
But if the hardening went well... Possibly it wasn't a complete transformation and the edge is a mix of martensite, bainite and pearlite. Not enough expansion to overcome the spine's expansion but enough of a difference in phases to make the hamon visible. Maybe... perhaps...
I can think of how to check for certain but it'd mean destroying the knife.
Incomplete transformation sounds plausible in my case. I don't have any kind of temperature control as this was done in a simple gas forge in the back garden by a novice making knives to amuse themselves. The only predictable part is probably the quality of the quench oil I got from GFS (Parks 50 equivalent).
While I'm disinclined to destroy the knife to do the check, I'm very interested to hear how you would perform that check.
If the whole knife has to be the same temp before quench, how does edge quenching work? I saw a master bladesmith edge quench to earn his master (Kyle Royer)
Aren’t katanas also edge quenched as well?
The type of steel used for edge quenching needs fast quenching to harden. If you’re too slow it won’t transform into martensite at all. With some grades you’ve only got seconds to get it from the furnace into the quench.
With edge quenching you are basically dipping only the edge into the water or oil so it quenches but leaves the back in the air to cool more slowly and avoid the hardening but remain fairly tough.
Does that answer your question? Or did i miss what you were really asking about?
@@GemAppleTom yes thanks!
Does the quench oil temp make any difference?
It can make a difference. The viscosity of an oil will affect how well it quenches and that will vary by temperature. But if the oil works when it’s not at its ideal temperature then it’ll work at the ideal (though extremes will make a difference - leaving oil out in an arctic winter isn’t a good idea). It will depend on the quench rate you need from the steel you’re using. You could get away with not controlling temperature with some steels but not others.
Using an oil at the wrong temperature can cause it to break down over time so keeping to the manufacturer’s recommendations should means it lasts longer and work at its best.
If you’re doing large numbers of pieces one after another then the quench rate will change as the oil heats up. Not an issue if you’re a hobbyist doing a couple of blades a day but mass production specs often do require control to keep the results consistent over batches.
PS: well it takes longer to do isn't a clay quench safer then an edge quench? well the exposed edge hardens faster, the isolation of the clay causing the spine to cool slowly. from doing a massive number of these i noticed you tend to be ready to go when your medium stops boiling.
hi gundanium, you might be correct. Thanks again for the comment!
does the orientation of a blade in a furnace/forge affect the amount of warpage in the steel i notice i have a warp in a blade after slow cooling it in vermiculite but i also had laid it flat in my forge well it got to heat, and it warped in the vermiculite? i am wondering the bottom of the forge acted as a heat sink on one side creating a heat differential that caused the warp.. i noticed the same thing happen to a few other blades i had done this with.
Distortion is fiendishly complicated so the most honest answer is "Maybe."
Yes, differences in the heating can cause warping. If I had a blade to put in a furnace I'd ideally hang it on a bot of wire. That won't be possible for a lot of furnaces, though.
To some extent you'll just have to deal with distortion. Normalising can help after forging and before hardening but won't guarantee you'll avoid distortion.
Any uneven or differential heating or cooling cycle has the potential to cause warpage. Another spanner in the works is internal stress in the original material. If it's there it will stress relieve itself on the way to the hardening temp and it's then impossible to say what exactly caused any one blade to distort.
@@GemAppleTom thank you both for answering. I went and did some work yesterday and i tried putting in some 'blocks' (two chunks of steel, then made two better ones from a thick cunk of leafspring) to prop it up on the spine after straitening a bent blade hot and then dumped back in the vermiculite and its strait so in theory this may have helped since I cant do a wire hang. (i want it strait because i want to do some file work on it before I harden it).
True for hardening. i noticed that how you move it in the quench tank can effect warpage. going side to side insted of tip to hilt to agitate the quench medium (i use parks 50) can cause the blade to bend and even crack as it converts to martinsite...after i cracked a lot of blades doing this (blush emoji).
thanks for all the help you do here Tom and your constructive comments are always appreciated! I hope you don't mind that I made you a moderator for the chats here in the channel. Thanks!
@@UKBladeshow I’m a what now?!
I’m enjoying the channel and it’s definitely a subject I’m interested in. If I notice anything obviously spammy I’ll remove it. Seems to be generally good crowd, though.
Hi Graham, if I overshoot my quench temp by a lot - like 150-200C - do I need to normalise and start again? Cheers. PS. You can always tell when somebody really knows their stuff as they never try to blind you with science, great job on that score mate.
Do you mean overshoot the temperature you want just before you quench - the hardening temperature?
(There are specifications in industry that specify quenchant temperature but I don’t think they’d be very applicable to knife making)
But it is science tho, idk what crack you're on
If you exceed the hardening temp by that much it's best to normalise (once) and start again
thanks for the comment J B!
I don't fully agree with what he says about normalizing.
I think the best way to normalize ideally is going to be to at least get it hot enough to be entirely sure all cementite has been dissolved. Which for most steels is fairly hot.
Then do another cycle at a normal austenitizing range. If not follow the normalizing cycle with a fast det anneal or something similar.
Because if you only do one lower normalizing cycle you aren't going to eliminate things like carbides that have grown during forging or formed on grain boundaries. If you are only getting it just not enough to fully austenitize but not hot enough to fully dissolve all austenite. But if you get it hot enough to dissolve all carbide, then it gets hot enough to grow the grain size.
All this rambling is to say 2 cycles makes then most sense. Either a high normalizing cycle, then a normal one. Or a high normalizing cycle and an anneal.
there’s many ways to skin a cat but a knife works pretty good and you could probably kill ALL the birds with one stone.
Will Graham write a book, or have some online course?
I wish he would! Thanks for watching!