Friday, October 18, 2013

DH1-2 HEAT TREATMENT

As the DH1-2 is a 154CM stainless steel, the electric heat treatment oven is used to accurately maintain the temperature for Austenitie-Martensite conversion.

I prepared the blade by placing it in a stainless foil envelope which is type 304 0.002" I bought from McMaster Carr. I cut it to 6" x 11" or so.





To consume any oxygen inside the envelope, I placed some tissue paper. Each seam is folded and pressed with a roller and then in the carpenter's vise.

This is the first time I have tried this technique, but from what advice I  have been given by several noted knifemakers I think this is the way to go.




Envelope as it looked when ready to go in the oven









 I preheated the heat treatment oven to 1050°C (1922°F) as prescribed in the Crucible Industries datasheet for 154CM. The temperature dropped to 1016°C from opening the door but soon recovered. A 50 minute soak at 1050°C and it was ready to quench.
 I have two 1/2" thick copper plates (4" x 13") that I used to quench the blade. This brings to a safe handling temperature in a few minutes. I did notice the envelope was inflated, so a good seal must have been maintained.
 Once I opened the envelope by cutting the end with tin snips. This is the results.









Interesting discolouration of the steel from heat treatment.


The tempering oven was pre-heated to 200°C (400°F) and waiting for the blade to go in. Two hours for the initial tempering cycle, followed by cool down and another two hour cycle.







The blade is now ready for polishing.





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