annealing before quenching?

C

cory

Joined
Dec 23, 2001
Messages
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Getting ready to start on a new knife from my supply of lawnmower blades. I tried 2 by heating to critical and quenching in warm oil. When clamped in a vice one shattered and one bent. The one that bent a good file bit into quite well so I junked it and the one that shattered the file did just the opposite. Nice smooth texture. My question is since I did this in a hurry I did not take the time to anneal either one. Why would it make the difference whether you annealed them or not just to perform a break test? Every one says to test a piece of unknown steel anneal, heat, quench, break. I just heated, quenched and broke. It should not matter (whether you anneal), should it, just for testing purposes? Cory
 
Normalizing before you HT is to remove stresses in the steel. IMHO it is the most important step in preparing the steel. Not all lawnmower blades are created equal. The soft one is just.......soft. Sounds like the other one may make a good knife!
 
Normalizing is a good place to start as well as heating to non-magnetic and quenching in warm oil with two or three tempering cycles.
This stuff aside, I recommend using steel of known composition. If you order bar stock form one of the big suppliers you do yourself a favor in the long run.
 
for testing purpose, it makes no difference. All you are trying to do is see if the steel will harden.and it sounds like you have a good piece.

But, Peter is right, When you are working with a blade ready for heat treat. It is another matter you MUST remove all stress(normalization) befor you harden.
:D :D Eric
 
If you only wanted to know if the steel had enough carbon in it to harden, then the heat and quench method is acceptable. If you plan on using the steel, then you should take the extra 30 minutes to anneal it before you harden it. It will make a huge difference in the granular structure of the steel observed after the break. Of course, if you heat it too hot, it will have the large grain anyway. A magnet will take care of that problem of overheating.
If you are forging the blades, then they should be normalized at least twice and then annealed after forging. This will reduce the grain size and stresses in the steel. If you don't start with the steel in the right condition, you can't achieve the most from the steel.
If you are just grinding the blades from the recycled steel, they are used and have had stresses induced into them, or work hardened as it is commonly called. They still should be normalized and annealed before hardened and tempered.
The first test to check the steel for carbon is sufficient. The time spent figuring out the carbon content and maybe what the manufacturer made them from is good research experience. At minimum wage, you would probably have more in them than if you bought the new steel that was ready to begin work on. The good part of recycled material is the story that you have that goes with the knife. And if it turns out to be an excellent blade, the story is even better. And then it
is an "heirloom".
I hope this helps some. I went through a lot of the same stages that most knifemakers go through. It is good practice to make knives from recyled material and when you start to acquire the skills of fit, finish, and heat treat, then it is time to invest in good, consistant quality blade material.
Ray Kirk dba Raker Knives
Since I haven't been able to get home much, I have been putting a few posts up with my Bride-to-be's computer.
 
Hey Cory, nice to see you back here! Looking forward to your new knives.

I'm using my daughter-in-law's computer right now, so gotta go, but I'll try to give you a call when we get home. I've been paying attention to these guys here and have some ideas why we got those voids in our cable experiments. I think we should try again, and winter is a good time to hang out by the fire!

Dave
 
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