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Post by Matt993f.o.d on Oct 9, 2008 21:09:35 GMT
I've had a bit of a setback.
I was 95% of the way through finishing a rather smashing 6.5" clipped point bowie blade. It was just being polished. I had got to the 400 grit stage when there appeared a rather unpleasant smudgy sort of unintentional "hamon" on the blade.
Basically, I had got an uneven heat when hardening. The edge had hardened and the spine had stayed soft. This was unsatisfactory, since the unintentional hamon type variation was uneven, and very aesthetically unappealing.
I've never had this trouble before because the biggest knife I have done has been four and a half inches in the blade. Not difficult to get an even heat on.
I really should have left it, because there wasnt really anything wrong with it. The edge was hard, after all. It just looked a bit too much like a naff amateur attempt at a DH, like so many do these days.
I thought I would re-heat treat the blade to get an even hardening. I tried twice more, but failed both times. I got fed up, and snapped the blade into pieces to assess the grain structure. As I guessed, it was f****d. Enlarged massively at the tip, fine in the middle and HUGE at the ricasso. Simply the result of a few too many heat treatments.
One thoroughly ruined blade. Two weeks of work down the pisser.
I'd have pics of the ruined steel, but the shards are in the bin. Sadface.
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Post by Deleted on Oct 9, 2008 22:31:17 GMT
It happens, don't let it bother you so bad, assess what was to be learned from it all and move onto the next one. Simply the result of a few too many heat treatments. More to the effect of uneven or overheating of certain spots, not too many heat treatments.
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Post by Deleted on Oct 10, 2008 1:44:37 GMT
Just out of curiosity...did you normalize between each heat treat attempt? Probably a lot of work but I think it would be a good insurance policy against poor grain structure.
Also, I really would have loved to see it finished! You guys have helped me out a ton, and I'm sure it would have turned out beautifully. Sucks when these things don't work out like we plan =/.
Cris
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Post by Dan Davis on Oct 10, 2008 12:24:30 GMT
Cris, Normalizing wouldn't do a lot for the grain structure; it would want a complete annealing cycle.
Matt, If you polish and then buff a blade it will not show a hamon even if it is there; food for thought. Many nihonto have "shadow hamon" but they are covered completely when the ji is burnished.
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Post by Matt993f.o.d on Oct 10, 2008 18:00:29 GMT
Food for thought indeed. Perhaps it would have been saveable. I don't think I would have wanted to anyway, though. The thought of such a wonky hardening hiding away would have annoyed me.
So I could have simply annealed it and tried again? I didnt think the steel had that much left to give. It had been through three separate heat treatments.
Cris, I didnt normalize between hardenings. I only normalize at the start of heat treatment (i.e. before I harden the blade).
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Post by Deleted on Oct 11, 2008 5:59:59 GMT
I see. My understanding (or misunderstanding?) was that normalizing...i.e. taking the piece up to just above critical, then letting it air cool to no more than 400*, then starting the process over again...was done to relieve stresses and create a finer grain structure. I believe I'd read on Donn Fogg's forum in a few different threads that if you were to fail a heat treat (usually too soft, or spotty hardness etc), you should simply begin your heat treat with your normalization cycle again. Usually three cycles to releive the stresses of the last hardening, and refine the grain structure of the steel, then harden again on the fourth. Sort of like making a few passes on a chalk board to 'wipe the slate clean' so to speak?
Is this incorrect?
I do know a lot of people interchange annealing, tempering, and normalizing on forums lol. Makes for a hell of a waste of time for a newbie bladesmith to make sure he's performing the processes correctly. Lots of double checking...and even when you think you have it right it turns out you may not!
Cris
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Post by Matt993f.o.d on Oct 11, 2008 21:28:09 GMT
Its not incorrect at all. BUT...
Everyone blahs on about how you've got to normalize X amount of times, harden X amount of times, temper for X amount of hours etc, but I think that is all way over the top.
Everyone does it differently, and they can't all be right.
I personally think that one normalization cycle prior to hardening should be enough if the steel was TREATED CAREFULLY THROUGHOUT THE WHOLE PROCESS. If you start with an annealed piece of steel, the grain structure should be fairly consistant throughout the piece. After forging, the grain structure should not be badly enlarged, it should in face be refined. If the blade is allowed to normalize after forging, any stresses that are present should be ironed out. After rough grinding, another normalization cycle prior to hardening to remove any stresses set up there should be enough to ensure an even structure.
Normalizing a third time shouldnt be necessary in my opinion.
Some smiths harden several times to ensure a thorough hardening. Why bother normalizing between hardenings? You would remove all of the work done by the previous hardening, so would be starting from scratch. Seems to defeat the purpose of trying to get as thorough hardening as possible.
Basically, people will tell you all sorts of ways of heat treating, but it is really a matter of personal preference. Use whatever methods work for you. So long as they DO work. If you really don't know if your heat treatments are working, try snapping some of your blades and observing the grain structure, as I have just done. This will tell you straight away if your heat treatments are working properly.
If you can do so and visibly show that the heat treatments you perform are getting good results, then you must be doing it right. From what I have just done, for example, I now know that I had not got an even heat, causing spotty hardening.
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Post by Deleted on Oct 13, 2008 14:08:51 GMT
Some smiths harden several times to ensure a thorough hardening. Why bother normalizing between hardenings? You would remove all of the work done by the previous hardening, so would be starting from scratch. Seems to defeat the purpose of trying to get as thorough hardening as possible. Basically, people will tell you all sorts of ways of heat treating, but it is really a matter of personal preference. Use whatever methods work for you. So long as they DO work. If you really don't know if your heat treatments are working, try snapping some of your blades and observing the grain structure, as I have just done. This will tell you straight away if your heat treatments are working properly. First of all, multiple hardenings is the half ass way to get full solution of all the alloys in a given steel made popular by Ed Fowler with 52100. He was not properly austenitizing the steel (mainly because he heat treats with a torch) so not all of the alloying elements were evenly disstributing themselves, so with each hardening you would bring a little more of the good stuff that makes that steel what it is into solution everytime and would see an advantage. What you should do is to just bring it up to the proper temperature, let it soak there for a few minutes then harden it, and you will probably see equal or even MUCH better performance from your steel. Do it right the first time instead of doing it half assed 3 times. The lesson to be learned here? DO NOT USE A STEEL THAT IS ABOVE YOUR CURRENT MEANS OF TECHNOLOGY. 1084 is the best beginner's steel because it requires almost no soak time once brought up to temperature, all the carbon and alloys come into solution right at temperature and it hardens acceptably (if you can accept that kind of thing) in your half ass vegetable or automotive oils, hardens BEAUTIFULLY in a proper oil. You can get a great knife out of 1084 simply by heating to non magnetic, then a little bit higher in a forge, hold that temperature, for a few seconds then quench, let it cool completely then temper in your oven at 400F for an hour (yes, time at tempering temperature IS critical). If heat treating on a simple basis, a normalisation is required or should be done before trying to harden again, but mostly if it warped from the first quench to make straightening it easier. LARGE GRAIN is not this huge catastrophic thing it is often blown up to be, it can simply be handled, and taken down to an acceptable level by normalisation, and the 3 normalisations tip everyone seems to give is because we can never be sure just what you did knowingly or UNKNOWINGLY to the steel during forging, and 3 cycles will take care of just about anything terrible you did unless you got the steel too hot and burned it then there is nothing you can do but start over. Normalisation is also not some magical fix all, it does what it does, same as hardening and tempering, all come together as parts of the whole heat treating process, eliminate one and the others don't do what they are supposed to.
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Post by Matt993f.o.d on Oct 13, 2008 16:30:45 GMT
First of all, multiple hardenings is the half ass way to get full solution of all the alloys in a given steel made popular by Ed Fowler with 52100. He was not properly austenitizing the steel (mainly because he heat treats with a torch) so not all of the alloying elements were evenly disstributing themselves, so with each hardening you would bring a little more of the good stuff that makes that steel what it is into solution everytime and would see an advantage. What you should do is to just bring it up to the proper temperature, let it soak there for a few minutes then harden it, and you will probably see equal or even MUCH better performance from your steel. Do it right the first time instead of doing it half assed 3 times. The lesson to be learned here? DO NOT USE A STEEL THAT IS ABOVE YOUR CURRENT MEANS OF TECHNOLOGY. Where are you coming from, Sam? Have I been playing with steel that is too complex for me? I can never be sure what steel I have been using as they are all done from scrap so far. This has made heat treatment much more hit and miss, as I can't really be sure what I am playing with. I don't really want to go buying pristine stock yet anyway, since I end up throwing away 3/4 of my forgings. I don't like the look of them, so they go in the bin. I havnt got the time to go polishing turds. As for the multiple hardening business, I try not to, but only do so if I think for whatever reason that the prior hardening/s were unsuccessful. You've told me before that grain growth isnt as catstrophic as it is made out, and I have paid attention here. It is actually this that I based my opinion that you don't necessarily need to normalise so many times on, as you yourself told me at the time that only one normalising cycle was needed if everything else was done properly.
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Post by Deleted on Oct 13, 2008 22:14:35 GMT
No it wasn't directed towards you specifically Matt, you do fine, but often times you see people going for that L6 or 1095 or O1 right out of the box.
As to the normalizations, 1-they can't hurt if you are doing them properly so why not, 2-you have to understand and recognize you are doing things properly so as not to need them.
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Post by Deleted on Oct 14, 2008 0:35:11 GMT
Some smiths harden several times to ensure a thorough hardening. Why bother normalizing between hardenings? You would remove all of the work done by the previous hardening, so would be starting from scratch. Seems to defeat the purpose of trying to get as thorough hardening as possible. Basically, people will tell you all sorts of ways of heat treating, but it is really a matter of personal preference. Use whatever methods work for you. So long as they DO work. If you really don't know if your heat treatments are working, try snapping some of your blades and observing the grain structure, as I have just done. This will tell you straight away if your heat treatments are working properly. First of all, multiple hardenings is the half ass way to get full solution of all the alloys in a given steel made popular by Ed Fowler with 52100. He was not properly austenitizing the steel (mainly because he heat treats with a torch) so not all of the alloying elements were evenly disstributing themselves, so with each hardening you would bring a little more of the good stuff that makes that steel what it is into solution everytime and would see an advantage. What you should do is to just bring it up to the proper temperature, let it soak there for a few minutes then harden it, and you will probably see equal or even MUCH better performance from your steel. Do it right the first time instead of doing it half assed 3 times. The lesson to be learned here? DO NOT USE A STEEL THAT IS ABOVE YOUR CURRENT MEANS OF TECHNOLOGY. 1084 is the best beginner's steel because it requires almost no soak time once brought up to temperature, all the carbon and alloys come into solution right at temperature and it hardens acceptably (if you can accept that kind of thing) in your half ass vegetable or automotive oils, hardens BEAUTIFULLY in a proper oil. You can get a great knife out of 1084 simply by heating to non magnetic, then a little bit higher in a forge, hold that temperature, for a few seconds then quench, let it cool completely then temper in your oven at 400F for an hour (yes, time at tempering temperature IS critical). If heat treating on a simple basis, a normalisation is required or should be done before trying to harden again, but mostly if it warped from the first quench to make straightening it easier. LARGE GRAIN is not this huge catastrophic thing it is often blown up to be, it can simply be handled, and taken down to an acceptable level by normalisation, and the 3 normalisations tip everyone seems to give is because we can never be sure just what you did knowingly or UNKNOWINGLY to the steel during forging, and 3 cycles will take care of just about anything terrible you did unless you got the steel too hot and burned it then there is nothing you can do but start over. Normalisation is also not some magical fix all, it does what it does, same as hardening and tempering, all come together as parts of the whole heat treating process, eliminate one and the others don't do what they are supposed to. ....so here's another question. I've been told to normalize more often to reduce the 'hardenability effects' of magnesium, to aid in my hamon formation. Now I understand that hardenability is based on a lot of things, while the actual amount a steel can harden, meaning the level it can harden to...is based on carbon content (not a contradiction in terms as it seems), but my question is, if normalization refines grain structure, reduces hardenability (I assume this is partially due to the refined grain structure?), and also somewhat relieves stresses, what's the hurt of doing it a few extra times 'just to be sure'? Please note, I'm not saying there is no harm in it, I'm asking if there is, and if so...what it is! This has been a good thread! At least you can say Matt, that the sacrifice of your poor bowie was not in vain...we're all learning something from it =). Cris
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Post by Dan Davis on Oct 14, 2008 14:51:09 GMT
Cris, NOT magnesium, MANGANESE. Everybody, some points: - Steels used for producing through-hardened, even temper blades work best when they are deep hardening and rapid hardening. Steels used for differential hardening to produce hamon work best when they are shallow hardening and slow hardening. Know what you want to do with your piece when you choose a steel.
- Annealed manganese-bearing (steels doped with manganese, not ball bearing) steel tends to be deep hardening and rapid hardening.
- This is absolutely dandy if you are doing through-tempered blades but sucks big time if you want to produce a hamon.
- Manganese is not added to steels to increase hardenability but it has that side effect.
- Each normalization cycle locks up a bit more manganese into carbides and therefore reduces it's side effect on hardening. In alloys provided by Admiral Steel this TYPICALLY takes 3 cycles, but not always.
Know your steels.
- Normalization cycles are also (and primarily) intended to reduce and relieve stresses induced by forging, exactly as Sam said. You normalize a blade, straighten it, and normalize it again. Repeat as necessary until the damn thing stays straight after normalizing (indicating that any major internal stresses have been relieved). This takes as long as it takes, as many cycles as it takes. Know WHY you are normalizing.
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Post by Deleted on Oct 14, 2008 17:07:08 GMT
Thanks Dan for correcing that! I wrote one thing while thinking the other lol. I'll leave it unedited for the flow of the thread.
Thanks to you guys, I've got a much better hold on the 'why' of it, rather than just the 'do this, it works' thing. That helps a lot when something unexpected happens during quenching, or any other phase of making a blade. If you know the 'why' you can often figure out what happened and how to either correct it or correct for it the next time. If you just know 'what to do'...that's pretty much impossible.
I hope you don't mind me treading all over your thread Matt! I just can't seem to help taking every opportunity I get to learn a bit more about what we're doing here. Any time I step on toes feel free to jump in with both feet and let me know lol.
Cris
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Post by Matt993f.o.d on Oct 14, 2008 17:21:05 GMT
No it wasn't directed towards you specifically Matt, you do fine, but often times you see people going for that L6 or 1095 or O1 right out of the box. As to the normalizations, 1-they can't hurt if you are doing them properly so why not, 2-you have to understand and recognize you are doing things properly so as not to need them. Thanks for the clarification, Sam. Rest assured that I for one certainly won't be playing with complex stuff for a good long time anyway. 1084 is fine by me! Cris, so long as it gets more good info out there, your tangents are quite welcome! ;D As for the wretched grain-enlarged bowie, I wish I hadnt broken it! Its replacement incarnation is not coming along well at all!
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Post by Matthew Stagmer on Oct 14, 2008 18:39:11 GMT
One way I have found to noramlize a piece like this is to take it up a yellow heat and then sit it in a bucket of white ash untill the heat is gone. This seems to work on most high carbon blades to get it ready for re-ht.
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Post by Matt993f.o.d on Oct 15, 2008 16:19:37 GMT
Is that if the first attempt failed?
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Post by brotherbanzai on Oct 15, 2008 18:00:49 GMT
This is a very interesting thread. I didn't know that you were supposed to normalize a blade again after straightening it though it makes sense that straightening the blade would set up stresses again.
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Post by Deleted on Oct 15, 2008 18:21:59 GMT
This is a very interesting thread. I didn't know that you were supposed to normalize a blade again after straightening it though it makes sense that straightening the blade would set up stresses again. Yeah...basically from all I've read...it can only help to normalize after any possible stress inducing process on the steel. Even grinding and filing can set a blade up for residual stress if I'm understanding things right. Basically, any metal shaping right up to the point of heat treat will do it. Is it a necessary thing? I don't know. Can it hurt? Not from what I've read! Cris
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Post by Matt993f.o.d on Oct 15, 2008 21:06:35 GMT
I can see how cold forming could set up stresses. Not sure how grinding can do so though. I mean, so long as you don't heat up the blade excessively when grinding, you shouldnt cause any stress, surely?
Although, if you do happen to normalize after grinding I guess it would help sort out any stress that COULD have been introduced. After all, you never know if you have or not.
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Post by brotherbanzai on Oct 15, 2008 21:42:27 GMT
It's my understanding (which could certainly be flawed) that if you don't normalize the blade before HT you could end up with a warped blade.
It's obvious to me now that straightening even a slight bend will stress the blade and it's been my experience that it is quite difficult and time consuming to grind on a blade without heating it in some spots. The first two big blades I made were totally stock removal and I didn't know at the time that I should have normalized them before HT and they both got a nice little corkscrew to them.
I just started on a pair of blades and after grinding the basic bevel shape I went on to try draw filing. I then discovered that a narrow strip of steel along one bevel had gotten hot enough to harden so that it could not be filed!
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