Normalizing Time Frame?

Eberjager

Member
First, even if it's maybe not necessary, it can't hurt to normalize O1, right? Second, can I normalize and then heat treat later, or do I need to HT and quench right away?

Lastly, is the right way to do it heat it to 1450-1500 then air cool - two or three times? (I have seen 1600 degrees mentioned too)

I do stock removal and up until now I have just HT'd and tempered. I think the results have been OK but I haven't really put my first couple of knives "to the test" much. My current project is much bigger and coming out well so far and I want to do all I can not to mess it up.

Thanks.
 
It will never hurt to normalize a blade. Even with stock removal stresses can be put into the steel that could come back and cause warping later. Also it never hurts to refine the grain; you never know what it's like from the foundry. There is not reason that you can't normalize and set the blade aside for hardening and tempering later. I do it all the time. I always stop forging with at least one normalization, even if I'm not through forming the blade. As far as the temperature goes you could do with the lower temperatures. All you need to do is to change the crystal phase. You're not concerned with getting carbon into solution in the austinite.

Doug
 
Thanks for the info Doug. I'm using a HT oven so I can do whatever temp is supposed to be best. Is it best to bring the blade up to temp with the oven or put in after the oven's up to temp? Or does it matter?
 
Not to take away from Doug's observations because he's way more technical than I am. I found just from observation in my own process that every time I tried to normalize O-1 I wound up with hard and soft bounderies. One spot was soft as butter when drilling and another seemed full hard and would make the bit scream. My conclusion....areas air hardened probably due to the chromium content. This made me wonder if those boundries were still there after HT. Had everything gone into solution ? I visualise it as islands floating in a sea of water. I stopped trying to normalize (O-1) and went straight to a full anneal after working the blade before HT with a 10 minute soak. That was in the 80's, I still use O-1 occasionally and don't normalize it still. Testing hasn't revealed any boogie men in the blades. I could be wrong and I'll take my licks if so.

Rudy
 
The full anneal could have given a better distribution of finer carbides where the normalization, especially if the steel got a littleh hot, could have caused the formation of courser carbides. Your analogy of little islands floating on the ocean wan't bad. You may have beed dealing with large clumps of hard carbides. A good reason to keep your temperatures down for heat treating, especially with hypereutictic steel.

Doug
 
There is no advantage or reason to normalize PG spheroidized annealed 01, unless you have forged it. Grain size will be as good as it gets, as is. You do need a pre-heat/stress relief soak at around 1250° before ramping up to the austenitizing heat which should not exceed 1475°, and then let it soak 15/20 minutes to get your carbides evenly distributed. Forged 01 is a different matter.
 
Back
Top