First attempt to heat treat on charcoal forge

[Shevtar]

Hello all
this is my first post here, I am currently building my first knife and as part of it I tried to heat treat the blade on homemade charcoal forge. The steel is 1095 CRA from jantz 1/8" thick
First I planned to put the blank into the tube to avoid the direct contact with the flames and actually did so,



but didn't heat it hot enough, in fear of overheating, just heated to non-magnetic (actully maybe even lower) and quenched in sunfloweroil. The blade was obviously not hot enough because there was no flame on oil, just hissing. I took a file and it bit, so the steel was not hardened properly, so I heated it again but this time directly in the coals and that time there was a bit of flame.
The blade afterwards had strange pattern

Just curious what can be the cause of such pattern, is that burned out carbon from the blade or what?
The file didn't bite so it was harder second time. Then I tempered it twice at 225C (437F), the blade had dark gold colour afterwards
The video of this is here (unfortunatelly in Russian)
[video=youtube;eIMCd5O0DeE]http://www.youtube.com/watch?v=eIMCd5O0DeE[/video]
some of the guys commented on the video that there is no need for the tube to isolate blade from the flame as if you heat it on charcoal the blade supposedly receives additional carbon from coals. Just wanted to find out what you experienced guys think about this? And I am worried about the fact that I actualy hardened it twice, because the first time the blade was not hard enough, and I didn't do any annealing in between , what effect it will have on the blade?

 

[One]

It's probably texture from decarb. This could make the blade feel soft on the surface.

Flames on the oil aren't really a good way to judge temperature.

The purpose of the tube or muffle is to help even out the heat and you should put a piece of wood in the back of the muffle, just prior to inserting the blade, to create a reducing atmosphere inside. This will help minimize the decarb.

 

[ricky_arthur]

It's decarb from getting it too hot. I heat treated about 25 knives in my coal forge before I bought a propane one.

What I do is get a pretty good size pile of coal burning and put the blade just on the edge of the heat where it would heat slowly. I would normalize 3 times, the first 2 normalization cycles at above non magnetic so each time I watched the color of the steel as It got to nonmagnetic. That way I had in my head the color I was looking for under the current lighting situation. (I was outside and color is different depending on time of day). Then I heated up to the color I was looking for, pulled out and tested for non-magnetic then put back in on direct heat to get just a little hotter, then quench. It takes a few times to get it down, but I only had the decarb problem once, after I realized what it was and what caused it, I changed to the above method.