Post-forging stuff to do before heat treating?

J

Jason Fry

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Jun 5, 2008
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All this forging stuff is relatively new to me. I can pound something to rough shape just fine, and I can do very well heat treating all kinds of bar stock in an oven. I'd like to make sure I can bridge the gap between forge and finished knife with as much precision as I can when I use an oven.

So, let's say I just pounded out a knife shape object. What are the recommended steps prior to quench?

I'm thinking normalizing x3 in decreasing heats will get me a long way. How does an anneal fit in there? How does a subcritical anneal at 1200 or 1300 x an hour or two compare to the more traditional "vermiculite" anneal? Does the annealing set up anything metallurgically that isn't already accomplished by the normalizing, or is it just to make the steel easier to grind?

We're talking 1084 here, BTW.
 
Jason, I wish I was as far down the road as you are, especially the forging parkway! Congrats on moving to that stage! I don't do any forging, but heat treating, I can parrot Kevin Cashen fairly well! I think you should do the regular normalizing routine, and that includes descending heats. No need to go below 1350F during that cycling, and three cycles is probably sufficient. Too many cycles will make the 1084 more shallow hardening...but that takes quite a few cycles. I would certainly do the usual 1650, 1550, 1450 step down. Afterwards, the steel is fairly soft, and can be machined (lemellar pearlite I think). But can be made softer with a spheroidized annealing, as you know, 1300 for an hour or two. How does that compare with the vermiculite anneal...I couldn't say. One question I have....I see the Japanese smiths using the vermiculite anneal on their white and blue steel knives, but I thought you weren't supposed to use that type of an anneal on hypereutectoids? The last question about annealing setting up anything metallurgically....from what I understand, it doesn't increase performance or anything like that, just makes it softer for machining. I think if you performed the anneal, you would have to increase the soak time a touch compared to a blade that wasn't.

Correction....I probably would use 1600 instead of 1650 for the initial normalizing heat for 1084.
 
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Jason-

A $1,000,000 question indeed. ;) :)

IMHO, it's best to keep as much precision control in the process as you can. 1084 is a lot more forgiving after being in the forge than some of the steels with a bit more alloy like O1, L6, or 52100... but still benefits from tight temp control.

I do a "sloppy" thermal cycle or two after forging. That will reduce wonky stress in the steel and soften things up enough to do things like cut the blade from the parent bar, as well as do a little bit of grinding to make sure I got the shape I wanted.

Then I go right to my salt bath, in your case it would be to the kiln... and do my reducing thermal cycles, including a subcritical anneal, then rough grind, harden + temper, finish grind.

I LOVE hammering blades to shape... but the truth is: it's very easy to royally screw up a bar of steel in a forge without staying on top of what's going on.
 
I think the sub critical anneal might ball up some of the carbon a bit and make the cold working a little easier. From what I have read, it seems a matter of preference whether or not you normalize before or after cold working. The cold working shouldn't effect grain size and the slight stress caused by it should disappear when you reach austenizing temperature.
 
Hi Guys,
I have never used 1084 before. Can it be cut to size and hollow ground like the stainless steels? Is an annealing process required or can it be shipped to a commercial heat treater? A knifemaker friend of mine wants to make blades out of 1084 and heat treat them with a set of torches. thanks.
 
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