Friday, December 26, 2014

DH44 - HUNTER: HEAT TREATMENT

To prevent decarburization (oxygen reacting with carbon in the steel) a stainless steel foil is used to make an envelope. The edges of the foil get folded up and pressed to make a seal. Once the knife is sealed in, it goes into the oven.
My quench plates are readied. These large copper plates that I place in a carpenter's vise.
In about an hour the HT2100 heat treatment oven and the wrapped up knife is up to temperature. I hold this temperature for about 20 minutes to ensure a good conversion.
Out of the oven...
into the quench plates. Within a minute the knife is cool enough to handle.
This is the foil after the quench.
Opening the foil envelope reveals a hardened blade with a small amount of oxidization.







After the hardening process, it's into the tempering oven to soften the steel a small amount. For CPM154 the recipe I like is 2 hours at 200°C (400°F). Allow to cool and repeat. The aim here is a hardness of Rockwell 59.





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