tkroenlein
Well-Known Member
Decarb is properly called decarburized steel. Most of the scale is oxidation that is a product of real hot steel plus oxygen, but mixed in that scale is a small amount of carbon that has migrated out of the steel at temperature. Decarb is "bad" in the sense that it doesn't finish well and it isn't as hard as it should be. When you're grinding a freshly hardened blade clean, it shows as milky or hazy colored steel instead of cleaner, "shiny chrome" colored steel. *[As the hazy layer is mostly ground away, if your eyes and lighting are right for the task, you can roll the blade around in the light and decarbed steel will show a very subtle mirage like reflection that appears to me to show the "dendritic" nature of the steel that is always running in the rolling direction of the steel.] It is that same dendritic pattern that is showing in your etched blade. So it may be that there is some decarb still present, or it may be banding as previously mentioned, that is more due to how it's been heated.
* In a few years of forum-ing, I've never heard anyone else describe seeing that dendritic pattern while grinding through a decarb layer. So I don't know if others can see it, I'm imagining it, or if no one else has ever brought it up. But that is my go or no-go when cleaning up a blade. It's very thin and is about 2 passes deep between 100% clean steel and obviously decarbed steel. Maybe I'm spending too much time looking at my blades when I'm grinding.
* In a few years of forum-ing, I've never heard anyone else describe seeing that dendritic pattern while grinding through a decarb layer. So I don't know if others can see it, I'm imagining it, or if no one else has ever brought it up. But that is my go or no-go when cleaning up a blade. It's very thin and is about 2 passes deep between 100% clean steel and obviously decarbed steel. Maybe I'm spending too much time looking at my blades when I'm grinding.
