Beginners o1 Heat treating and tempering question

[drlloyd1]

I recently made a knife out of o1. After heating the blade to non-magnetism,then I quenched the blade in 120* olive oil. An hour later I placed the blade in the oven for 2 hrs. at 475*. The metal which was thin (3/32 inch) because of the knife design was warped and I proceeded to gently straighten it in a vise. However the blade instantly broke. My question is how much flexibility can you expect with o1 using the above sequence of operation. Then, what can I do to keep these blades from being this brittle? Thanks

 

[tejas7]

I usually temper at 400. I am suprised that the knife broke (at least you can be assured that it got hard). I do not know how bad the warp was but usually it will flex quite a ways even without a soft spine draw.

Normalize the blade after grinding and before hardening. (Heat to non-magnetic and let air cool). Since I started normalizing my blades, I do not think I have had any warp. Hopefully, someone more knowledgable than myself can give some more detailed info.

 

[Chuck Gedraitis Knives]

I heat my O-1 blades to 1500 and then quench in oil or radiator fluid. They are hard cause I can't scratch them with a file. I also temper at 400 deg, but for an hour, then I let them cool, and then temper again for another hour at 400. If you quench the blade horizontaly instead of vertically (tip up or down) you will get a more even quench. If it it is done vertically, the blade cools at different rates as you plunge it into the quenching medium and thus warps. Thicker stock might also be less likely to warp.

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A Knife is no more than an Iron Tooth

 

[cutline blades]

all my blades are O-1..and i heat treat just like striper28 says except i use 350..i have every one rockwell tested and they come out at58 to 59 rockwell....from what i`ve expierienced O-1 is not a big flexer , but it shouldn`t have broke from just trying to straighten...i`ve also had the problem with warping thin blades of O-1...the thin stuff i make are made of A-2....edge quenching might help for O-1 but i`m not sure...also try to straighten right after temper while the blade is still quite warm...it`s worked for me

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i keep grinding and grinding and it is still too short!!

 

[C_Claycomb]

Um, I am a total newbie, not finished filing my first blades of 0-1 but I thought that you were only able to straighten warp BETWEEN the quench and the temper. Once tempered I would have thought that it was way too hard (or whatever) to be straightened. Sure I heard somewhere that after the quench the metal could be bent quite easily.

Definitely going to try quenching horizontally, edge first when I get there.

 

[Bruce Bump]

I think maybe you over-heated the thin steel before quenching. This will cause grain growth and result in a weak finished blade. It is essential to normalize after forging to reduce the grain size. Even stock removal blades may need to be normalized to reduce grain size. You can look at the broken end and see the exposed grain; is it fine or course? Thin metal doesnt take to overheating as well as thicker. You may have the torch too hot or maybe slow with the magnet, use a small tip on the torch, turn the lights out so you can see the metal color better. After nonmagetic, look for shadows (cold spots), dont burn the tip of the blade, then quickly quench and dont go sideways which may bend the blade. Staighten bent blades in a vice (but not with a hammer) as soon after quenching when cool enough to handle. I like to edge quench for maximum flexability. To do this, simply heat the edge area instead of the entire blade before quenching. Leaves a nice hamen line too. Temper at about 375 for one hour, sharpen a section and do an edge flex test. If it is going to break it will only chip the edge this way. If it chips the edge, retemper to 400 for an hour. and retest the edge. It is right if the edge flexs back to staight after flexed. I have a box full of bent and broken blades. I passed my journeyman test for American Bladesmith Society this method under Master Wayne Goddard. Bruce

 

[DanL]

Get your self an oven thermometer, you may not really be at 475dgs. My heattreat oven (toaster oven) temp setting dial was off by about 40dgs.