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Old 03-31-2016, 10:27 AM
samuraistuart samuraistuart is offline
Steel Addict
 
Join Date: Dec 2012
Location: San Antonio Texas
Posts: 163
What is decarb? My definition.......decarb is the answer to 95% of the threads with titles "why didn't my steel harden after I followed the HT carefully?".

Scale and decarb are too often confused as being the same thing, and they are not.

Steel is heated towards and past Ac1, carbon leaches out of the steel and is deposited onto the surface. That carbon layer on the surface is known as scale. Can be removed by vinegar soak, or grinding it off with a wire brush even.

Because the carbon has leeched out of the steel and formed a scale layer on the surface, below the surface is going to be a thin layer of steel that has NO carbon in it. This is the decarb layer, and can NOT be removed with vinegar. You must sand/grind through it to get to hard steel. How thick this decarb layer is will depend on a few factors, how hot, how long, maybe carbon % not sure.

Sometimes the orange peel look is a decarb layer that has not been thoroughly sanded thru, only lightly sanded into, and thus can resemble the orange peel look. Also, it can resemble an auto hamon. If you had a blade that had a fairly thick decarb layer on it, and you only sanded thru the decarb layer (evenly) near the edge of the blade, and etched it with vinegar or FC, it can resemble a hamon or lamination line.
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