Post-forging stuff to do before heat treating?

J

jkf96a

Well-Known Member
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?

Got a hammer in this weekend, might as well get started. Only 2 more years till I can do my JS :)
 
Personally, I don't anneal and I think that there are others who don't either. That slow cool down can grow large carbides. I forge, temper, then grind to close to finish then heat treat and finish grinding. Some grind in the bevels after heat treating if they are dealing with a thin blade.

Doug
 
I'm assuming your using some type of gas or coke forge to heat the steel. As you get close to the end of the forging process and the blade takes shape and gets thinner, lower the heat and work at lower temps. I work at 1600 1700 towards the end. Cool the tip as you work, get in the habit of quenching the tip and back in the heat to work the ricasso area. This not only refines the grain in this area but it keeps it from burning up in the heat. I run 1200 stress relief after forging, spherodizing be accomplished at the same time. Lots of stress right after forging Now you have a stress relieved blade that is quite soft, ready for drilling, filing shaping. The three step normalizing works well. Takes a little time but worth the effort. I've been following the above for 10 years and I don't get any warped blades not even the thin ones. What ever else you do take the ricasso area to 400 with the shoulders set. Don't want to touch them after heat treat other than clean up. The side of your anvil is a great place to keep the blade straight as you forge. Looking down from the top you can see how straight it is at a glance. Learn to forge to shape as close as you can. You might not do so every time but, it improves your skills tremendously.

Enjoy, Fred
 
The first thing I thought of when considering my advice is what steel are you using? If it is a simple carbon steel with less than .8% carbon it will call for a slightly different approach from one with more than that amount of C.

Also, a language error has become fairly mainstream in the knifemaking community and since I believe I played a large part in propagating it I feel it is only right that I do my part in helping correct it. “Normalizing” is a very specific heat treating procedure done at certain temperatures for a specific effect, but we have come to refer to almost any heating and cooling that does not specifically harden or anneal the steel as “normalizing.” Heating to above Ac3, or Acm (or simply Ac1 in a simple exact eutectoid steel) and air cooling for the purpose of homogenizing the internal condition of the steel is normalizing. The follow-up descending heat cycles we often use cannot fall under this definition, as they utilize lower temps which would fail to address homogenization via carbide solution, and they sometimes even include more rapid rates of cooling. These subsequent operations would more appropriately be called thermal cycles, and are more for grain refinement than anything, in fact if over done in the lower ranges they can undo what you did to the carbide condition during normalizing.
 
Thanks, guys. 1084 is correct, and I found Mr. Cashen's explanations on the ABS site helpful as well. When I said "normalizing", I was in fact referring to thermal cycling.
 
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