temper line?

I understand the hardening process but have ofter wondered why a temper line is visible and exactly what it is that we are seeing. Maybe one of you metalurgists can explain it.

Gary

Gary, I'm pretty sure this is a good question for Ed Caffrey. It's sure a lousy one for a guy like me!

I'm not a metallurgist, but some recent reading I did might help you. Heat-treatments change the size and relative positions of the compounds within the microstructure in the metal. If you differentially temper (apply different treatments to the same piece) the blade, what results is a separation of patterns within the steel, and these patterns are revealed by comparison along the line of demarcation over which the different patterns were applied.

That reads like it was written in Newfoundland, and I am sorry about that. I tried to rewrite it three times. If you're offended by this next bit, I will be heartbroken, but I want to say it anyway.

If you go to your local library you can pick up a basic book on metallurgy. A picture says a thousand words. The photos of the different microstructures of steel, alone, will compensate you for your time a hundred times over.

Please don't write like Newfoundland. I just can't deal with another Newfie Knife Know-it-all!

Thanks, guys. Sam. what you said makes since and has gotten me even more curious about the visible difference. I guess that when I have a free evening I'll have to see if the Newfoundlanders have anything on the Online Public Library.

Gary