Thread: Re-hardening?

Originally Posted by Mike Blue

One other thing I could be curious about is your tempering temperature (the post hardening stress relieving aspect), that might lower the final hardness. But, if it skates a file, it's probably hard enough that it shouldn't be giving you so much trouble. Other factors are that scale can be hard sometimes and tempering the scale will make it seem much softer than the meat underneath.

This is where a keen observer will rise to his full strength. You're there with the blade in hand, while the rest of us depend on your description, times, temperatures etc. And, there are a lot of variables. Sounds like you're working a good program though.

Well what I discovered in the end is that I definitely didn't have it in the furnace long enough the first time to through harden. Maybe it case hardened?
In any case there was no visible decarburized pattern underneath the scale first time; there is this time.
Secondly the tempering process was done at the same temperature as last time (230°c) but this time it turned a nice shade of bronze, which it didn't do last time.

I haven't had a chance to regrind and start honing but it all feels better this time. More "right".

Thanks for all your help

Ash

Originally Posted by shooter74743

This is what I do, why? Mike told me to do it...when I didn't listen: potato chip

Lesson learned.

Listen to Mike.

Room temperature slows the quench, so I believe. It's due to the viscosity of the oil being much higher at room temp, thus heat transfer slower even with agitation. That is probably why potato chip but I guess I am lucky that my edge didn't go all crinkle cut on me.

Bronze sounds really good. Cool. Pix when done, don't just keep us all on edge....