Saturday, August 24, 2013

BC1 - TEMPERING

 TEMPERING



Tempering or "drawing" the steel involves heating it to around  250°C for an hour or two. The steel takes on a yellowish hue. When the tempering is done the blade will be hard yet flexible and fairly easy to sharpen.

For my heat source I used a counter-top oven that I setup outside of my garage. (It was going to be a hot one today and having the big oven in the house on for several hours at near full heat didn't sound appealing.) I placed the over thermometer inside and set the blade on a block of steel.

I heated up the oven to about 250°C (475°F) for two hours, then let it cool. Once cooled to about 25°C, I repeated this cycle. Crucible recommends 2 soaks of 2 hours at 204 to 425°C. This temperature impacts the overall hardness. The aim is to get the steel hardness between 59 and 62 Rockwell C.

Different types of steels have different recommended tempering schemes.
 The blade definitely takes on a yellowish tint, almost golden. Very nice, but I will be polishing that all off shortly.




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