Heat Treating O1 Tool Steel Lathe Bits

[Billh50]

It could be that the tool was tempered too much so that the hardness was not great enough to last. I have seen people temper things to the point they are not much harder than they were to begin with. With the cutting tip being so small it may have tempered too much.

 

[epanzella]

Thanks for everyone's input. The first time I hardened the tool I used a neutral flame. Yesterday I rehardened the tool a bit slower with a carburizing flame until non magnetic and then quenched it in oil. I didn't draw the temper at all. I repeated the exact same threading operation that dulled the cutter the first time and there was no detectable dulling of the edge. It's amazing how seemingly insignificant changes can make such a big difference in the outcome of a project.

 

[T Bredehoft]

Glad to hear you had success with O1. I will amend my opinion of it.

 

[dracozny]

You were very close, looks like you found some charts to help you. Soak times are generally 1 hour per inch, For O1 hardening is done at 1500 deg F. Something like a cutter can easily be done in 10 - 15 minutes. Quench in oil at room temp is fine.
For Tempering for a Rc of 63 you were on the money of 300 deg F for O1. I have never heard of anyone tempering in an oil bath though. Molten salts sure, but not oil. I have an old metallurgical chart from when I did blade smithing that I use. unfortunately I can't find that chart online anymore. This one is a bit basic and lists slightly different temperatures and times.

As mentioned above an oven is ideal in this situation even a small forge with a K thermocouple is a great tool to have. Tip for using a thermocouple: Wait for your work piece to be the same color as the thermocouple before starting the timer.

 

[dracozny]

I think this forum software is going to kill me.