My Steel Won't Harden!

Milo, I had most, I wish this site existed when I went to college.

Thanks for the review,

I do have a two questions though, its about #2, on Decarburization

First what would cause Decarburization

and second is there a way to induce carbon back to the surface.

It's reverse process when you do carburization process.- same temperature or higher with less or no carbon on surrounding environment.

Read the concept of diffusion/diffusitivity

One thing you didn't mention is overheating. This happened to me one time with a fairly large A2 tool. My oven overheated due to a faulty temp controller. I estimated that the oven got well over 2000ºF (should have been 1750). After a normal air quench and a 400º temper, I realized something was wrong when the piece wouldn't hold on the magnetic chuck of my surface grinder. The steel was still austentite.

I was able to save it by a full anneal and a new heat treat at the correct temperature.