Thread: Heat damage?

Yesterday I re-heat treated the blade. I sparktested it afterward, and it gave a nice clean spark along the length of the edge. In other words: success. Although the proof of the pudding is in the eating. I.e. in the shave. But for now I am happy with the result.

Before people think that this will always work out well, let me say that I think this only worked because it was a wedge with a fair thermal mass. A hollow ground blade will probably lose too much heat when taking it out of the fire. I also took a couple of precautions in my setup, and I went with a couple of assumptions.

first, the assumptions. This razor had a ruined temper. I assumed that before that, it was a good razor with fine grain and zero stresses. In other words, I did not anneal it as I would with unknown steel. I also kept the soak time to a minimum. After all, the business end of the razor was thin already, so soak would not really be needed, as long as the larger thermal mass (spine) had the correct temperature, the edge would be ok. I did this to minimize the time needed at high temperature, to protect the carbon in the blade. I just heated to the right temperature, and then a single quench.

then, the precautions. the first precaution was to coat the entire blade with a fine clay wash. thin enough to not impact the heat treatment, but enough to keep oxygen away from the blade for the minute or so it would be at critical temperature. Then I took a piece of thick walled steel pipe, which I hammered shut at one end. this pipe went into the fire. the purpose of the pipe is to keep the blade away from open flame, and to create a much more even and controlled source of heat. this also served the purpose of allowing me to put the blade in the fire without scraping the clay coating or bending it.

I waited until the entire pipe was glowing at an even temperature, then inserted the blade. checked the blade color a couple of times, and as soon as it was the right color, I quenched in oil. initial spark testing showed a very nice spark along the entire edge. I tempered it at around 175 degrees celsius.

I'll just clean up the suface grind, and then it can go back to the owner for sanding and clenaup.

This is great news! I am so thankful for your assistance! Please check your PMs!

what? no pictures?