HT 1095/15n20 Damascus

Greenberg Woods

Greenberg Woods

Joined
Dec 27, 2013
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Hey guys, I have heat treated both 1095 and 15N20 separately, but together raised a few questions for me. 1095, being hypereutectiod, requires a soak to melt the carbides to get a good, even steel, while 15N20 has a carbon content of .75, below the Eutectiod point. I have also seen differing rates for quench and temper. The whole situation seems a little confusing, so my questions are,

A) To soak or not to soak? I don't see what harm it could do the 15N20, but i would like to make sure.

B) Tempering. With my 1095 i like to do two two hour trips at 500, cooling to room temp in between. Would this be the same with the Damascus?

C) Some people like to do triple normalization and triple quench. While i have never done this before, it makes sense for shrinking grain size.

Thanks in advance guys, I have been reading plenty of metal chemistry but this issue has been giving me trouble, and the blade is for my father and i want every detail to be perfect.
 
Your carbon content will migrate and equalize rather quickly, plus you will loose a little bit, so you can determine your carbon content with a bit of math figuring in a loss of .05-.1% and the thickness/number of bars you started with... not precise but it will get you in the ballpark +/-.05%. Your carbon content will determine if you need a soak.

If your tempering temperature is 400f for 15n20, and 450f for 1095 (500 sounds a bit high to me), so 425f should be perfect... some testing might be in order though.

I would definitely suggest thermal cycling (what most of us knifemakers do does not really qualify as textbook normalization) damascus due to the high temperatures it has been subjected to while being welded. Quenching more than once is not needed unless you didn't get it fully hardened the first time. I would suggest using a fast oil for a quench.
 
I use the rule: "HT for the steel that will do the cutting". That will be the harder steel. In 1095 and 15N20, I would go with 1500F and a ten minute soak. Quench in fast oil. Temper at 425, as GHEzell suggested.
 
That makes sense. I looked up thermal cycling, and i could only find industry definitions, nothing in relation to knife making. I understand that the steel would have high stress after the high heat and pounding of the welds, so normalizing makes sense, but what exactly do you mean by thermal cycling in relation to knife making?
 
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