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Questions About Damascus


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Hi Alan and hello to all of the other Smiths out there who have been so generous with your knowledge!!

 

I have a few questions about Damascus. I have just made my very first Damascus billet!! It's 64 layers of 1095 & 15N20.

 

First question is: How can I judge when the steel is the right temperature for quenching? (I don't have a pyrometer but could use some advice on a decent quality, reasonably priced unit.) I have heard that the steel should be salmon colored and just beyond the point of non magnetic. Is that accurate?

 

Second question: What is the correct tempering temperature and amount of time? (I don't have a tempering oven, just my regular household oven.)

 

Third and forth questions: What type of acid should I be using for the etch and for how long should the steel soak?

 

Lastly, any other advice or details I may be missing would be greatly appreciated!!

 

Thanks everyone!!!

 

:D

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Decalescence and recalescence are great ways to determine phase change for all your normalizing and quenching needs.  Magnets are not very useful in heat treat, as they just tell you when you have reached the Curie temperature (about 1414 F), which is generally going to be at least 50 F too cold, often more than that.  

 

Your temper temperature is really going to be dependent on the nature of the blade.  Razors need to be quite a bit harder than machetes, for example.  When using your kitchen oven it is advisable to get a thermometer to double check your oven's temperature, because the built in ones are often not very accurate.  It is also a good idea to have some thermal mass so you don't get as wide of temperature swings.  I like a pan of sand, as you can bury your blade in it and really have an equal temperature.  

 

Many smiths really like ferric chloride (technically a salt, not an acid).  Soak times are going to depend on concentration of the solution and what you are going for (light etch vs heavy topography).

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For a good description of decalescence go down to the "heat treat by alloy" subforum and look up 5160.  That's why it's such an important phenomenon, it works on all simple and low alloy steels no matter what their critical temperature may be.  When the swirly shadows go away, the transformation is complete, be that at 1450 F or 1650F.  After all the forging you did to get it into damascus shape, it doesn't need a soak.  Just a couple of normalizations, then a quench.

 

If you use hot (130-150 F) canola you should get good results.  90 degree Parks 50 is even better.  The main thing is to get it from the forge to the quench as fast as possible.  With 1095 you have less than one second to take it from 1450F to 900F.  

 

Do two temper cycles at one hour each.  350F is a good starting place, but will be too hard for a chopper.  If you're married, and you use bricks for thermal mass in the oven, wrap them in foil first to maintain domestic tranquility.  Also, while it's important to get the blade from the quench into the temper as fast as possible (and absolutely within an hour), be sure to thoroughly degrease the blade before you stick it in the oven.  Canola isn't bad, but if you use an industrial quench oil the smell will put you in the doghouse.

 

Ferric chloride, PCB etchant, is the standard.  If you get the liquid kind, I like to dilute it 4:1 with distilled water.  Degrease the blade well, and don't touch it after. The etch is faster if the etchant is warm, so time is relative.  Just to see the pattern  a few 30-second dips followed by wiping off the black will show.  For enough topography to maintain the etch, I like a few ten-minute soaks with wiping off the gunk in between.  Neutralize the salts after the last etch with ammonia (windex with ammonia works fine) and stabilize the dark by either boiling the blade or by heating it to 212 degrees or so  and holding for half an hour.  Then lightly sand with a single sheet of your highest grit paper you used on the blade glued to a hard backing. This will polish up the 15n20 without marring the 1095.  If after that it's still not contrasty enough for you, soak overnight in 4x strong instant coffee and repeat the final sand.

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RLOL. THANKS  for the wrapping bricks suggestion. I'm a bachelor  so I never gave that a thought when telling married friends about heat treat in ovens. 

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7 hours ago, Alan Longmire said:

be sure to thoroughly degrease the blade before you stick it in the oven. 

or you can wrap the blades in aluminum foil before throwing (er, I mean, gently placing:unsure:) them in the oven.

 

And for judging temperature, IIRC, table salt melts at about 1475F, so sprinkling your blade with this and watching it to bubble just like flux might help judge your temps.

 

Oh yeah, don't forget:  Pics or it didn't happen:D

Edited by billyO
RIP Bear....be free!

 

as always

peace and love

billyO

 

 

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Thanks so much Alan, Jerrod, Kreg, Vlegski and BillyO for all of your great advice!!

 

One of the many things I love about this forum, is the generosity of knowledge that all of the Smiths share so graciously!!

 

And BillyO, I will definitely post the pics when it's finished!!!

 

:D

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