Heat Treating Damascus - concepts???

C

Cushing H.

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I am about to send off a couple damascus blades to JT for HT .... steel made by WEO .... and mostly for my own curiosity/learning I had some question about the "why" of HT parameters that WEO thought might be appropriate to post to the forum....

So .... this steel is 15n20 / 1080, and I would like to target 62 HRC or so. Apparently 1080 is to be austentized at "heat no higher than 1500F (http://www.cashenblades.com/steel/1080.html) , and 15n20 should be austentized at 1480 (https://www.alphaknifesupply.com/shop/15n20-carbon-steel ). so I guess 1480 it is (with oil quench)

But with tempering, the same references above give something (for 62 HRC) like 300F for 15n20, and 375F for 1080.

So .... what do you do - choose something like 300F, and hit 62 for the 15n20 (and accept that the 1080 will be harder), or choose something like 375F to hit 62 for the 1080 (and accept that the 15n20 will be softer) ..... or is it more complicated than that given that the two metals have likely been sharing components due to diffusion during the forging process????
 
It isn't quite as simple as putting two separate knives in the oven for HT. The damascus is not 15N20 ands 1080 anymore. It is an amalgam with the carbon somewhat diffused throughout. Probably around .70% carbon by now ( decarb) and the manganese will be around .5%. The nickel doesn't diffuse as-such, but is evenly distributed throughout the billet. This will make your target parameters best using the HT for 15N20.

JTv will probably temper low and test the hardness. He will adjust the temper to hit your requested target. If you find the blade chippy ( not likely) after finishing the bevels and testing the edge, re-temper 20° higher than the final temper by JT.

Here is a graph of the two metals:
upload_2021-1-31_14-22-56.png
 
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