Temper/normalize?

Osbourn

Osbourn

Joined
Jun 27, 1999
Messages
804
This is a funky piece of anecdotal evidence for people to debate the why of.
I'm in the process of doing a batch of 12 blades for an upcoming festival. 9 5160 daggers and 3 1095 seax(basically wharncliffs.). I was pressed for time on the heat treat and knew I wouldn't have a chance to normalize beforehand, so I put them in the oven at 600 for three hours while I took care of household neccessities. I figured I'd have some straightening to do, but I would have to live with it due to circumstances.
I did the quench with all of them in sequence in hot olive oil (around 200f) and the only warpage I experienced were in the two of the single edged blades that I was doing a japanese-style heat treat on, so warpage is expected on those.
I wasn't what I would consider gentle on either the forging or the grinding of these daggers, and nine with no warpage seems a bit beyond chance by my calculator. Am I on to something with this oven trick? Or could some other factor be saving me from what I thought was inevitable warpage?
 
Go figure Oz! You may be on to something or you may just be lucky. I've banged away at blades and gone right to heat treat. They come out straight as an arrow. I've also normalized and come out with boomarangs.
 
The 200F temp for the oil is a bit too warm for the blades to fully harden. Anything past 180F and you do not get complete transformation in the matrix, which gives you a softer blade. Without getting too involved in exactly what happens.........the easiest way to explain it is, because the blades did not likely reach full hardness, there was very little stress placed on the blades, therefore warpage if far less likely to occur. Just my thoughts on the matter. :)
 
200 is more of a SWAG than a real temp. I don't have a candy thermometer dedicated as I should. Thinking about it in depth, it was probably closer to 120. I checked it with my finger, and didn't quite get a first degree burn. There's some variance in there, though, since I was outside and the humidity was doing all kinds of strange things.
In any case, I'm pretty confident that martensitic transformation happened in all but one of the blades, and I've redone that one since. I did the last two, the clay-coated ones, one right after the other, and the oil was too hot for the second, so it's hamon didn't show. The rest of them had plenty of time in between quenches for the oil to cool, and one I had to heat it up a bit again.
 
The 600 was just a really soft temper, basically. I figured it would be better than nothing along the lines of normalization. I couldn't normalize because I had a limited window of opportunity to do the quenches.
 
Osbourn,
It is good to see a maker concerned with the little things. Don't lose that. I understand now what you were trying to do.
Honestly, I feel the 600°F method you employed will have neither a positive nor negative outcome on the quality of those pieces.
Normalizing should be carried out when it is necessary. There are a lot of guys who blindly use the method thinking its some sort of magic button. Its like thinking cryo adds a notch of performance no matter what.
What method are you using to harden and temper your blades? The forge? A torch? A kiln?

-Jason
 
I think that you have forgotten one of the most important reasons for normalizing and then annealing. GRAIN SIZE ! With out the proper thermal treatments then you are not going to be able to achieve the minimum/optimum grain size/structure that the steel that you are working with is capable of.
 
I know Oz, I'm sure he normalized immediately after forging the blades. He just skipped the normalizing heat prior to heat treating due to time constraints.
 
Burke,
This may come across as heresy but I have found, done properly with the right equipment, certain annealing techniques before hardening, work just as well with a normalize or without. My blades have a very fine grain and are tremendously shock resistant. Now, this is just me, with my methods, tools and own design. Don't get me wrong here and don't take offense but, normalizing has its place, but I still feel that there are alternatives to getting fine grained steel.

-Jason
 
Jason,

You are quite correct. But isn't annealing just a normalizing cycle streched out over a longer period of time? The point that I was trying to get across is that thermal cycles lead to small grain. And to acheive the smallest grain that a certain type of steel is capable of then you need to have good thermal cycles. Can you get small grain size without thermal cycles? Could you get smaller grain size with more/better thermal cycling? By what means are you judging grain size? Have you sent some of your work to a metalurgist and had it disected and annalized or are you just breaking a piece of steel and looking at it?
 
Burke,
No, actually annealing is not a stretched out normalizing session. Normalizing is rather rapid compared to any of the annealing methods and produces a finer grain. However... once you have re-heated the steel AGAIN into austenitizing range, your grains have now undergone change. You no longer have a normalized steel, that structure is now gone or is going. Instead, your final grain size will now be dependant on how hot you get that steel, how long you hold it, how fast you cool it, how homogenous the heating and cooling is, etc.

What exactly did you mean my "thermal cyles"? I know a lot of bladesmiths use this term, but they are always a bit different in their method.

My understanding for judging grain size is simply whats in every ferrous metallurgical text. My own personal method, on my own blades is pretty simple. I look at it. :cool: Broken that is. I have not had metallographic testing performed, although it would be interesting to see under a scope, just for kicks. :cool: However, I am 100% percent positive of the results I have found in my own work, so there has been no need for lab assitance.

Sorry, tried to be brief, I gotta catch myself from rambling.
:D

-Jason
 
Guy is right, I always normalize or anneal after forging. I annealed all of these blades as my final forging step, standard procedure these days.
While grinding the reason for no warpage occurred to me. These things are bloody thick on the edge. Quite a bit thicker than the 1/16th I usually prefer, but I was being cautious since these are my first double-edged blades and I thought (correctly) when I was rough grinding them that I would need quite a bit of leeway for corrections in the final grind.
I have eight of the batch final ground and polished now, ready for their fittings. :) All indications on these are that the heat treat worked well. Both of the ones I attempted a japanese heat treat on went south, though. One of them has a hamon, but not one I'd put on a table with my name on it, so I'm going to give them homogenous heat treats. They're norse blades anyway.
Terry, the festival is September 7th in Jacksonville, Riverside park at 'Historic' Five Points. Come say Hi! I'm the long haired guy with blue glasses sitting behind a table with knives, runes and jewelry on it. I'll probably be accompanied by a pregnant blonde. I hope this narrows it down enough for any interested party to find me.
Thanks for the input from everyone.
 
Osbourn,
Well, I'm glad to see you have things figured out and going well now. Good luck!

-Jason
 
Bill (Burke531) Glad to see that your computer is working again. Give me a call ASAP so that we can talk about that blade that you sent. Thanks.
 
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