how much heat to destroy heat treat?

[resinguy]

When sharpening on power equipment you gotta be careful, because it's easy to hit 2000 F at the very edge if you let the blade linger in one spot too long.

2000F, just from grinding? Really?

 

[ridgeline]

When sharpening on power equipment you gotta be careful, because it's easy to hit 2000 F at the very edge if you let the blade linger in one spot too long.

Seems hotter than I imagined....

 

[Joshua J.]

I agree that you can easily reach extreme temperatures when machine grinding.
It's not hard to get steel to turn all sorts of pretty colors, like, glowing red.
Here's a guide Google pulled up for me.
http://www.muggyweld.com/color.html

 

[yoda4561]

2000F, just from grinding? Really?

Oh yeah, if you really want you can get an entire blade red hot during grinding. I think Bob Engnath used to do that (he was a big fan of push-sticks and heavy gloves when grinding ) Years and years ago when I was learning to sharpen on a belt sander I got a bit too focused on spot damage and leaned in on it a bit. Next thing I knew the edge turned yellow hot and a good half inch into the grind turned colors. I was practicing on some mild steel blanks I made, so no quality knives were ruined in this post Just goes to show how quickly a thin cross section of steel can heat up. Knifemakers who grind post heat treat combat this by using new, sharp belts and dipping the blade in water to keep it cool enough to handle.