c5532be8   
   On Thu, 7 Apr 2011 17:53:07 -0700 (PDT), Father Haskell   
    wrote:   
      
   >On Apr 7, 8:13 pm, goodsoldierschw...@gmail.com wrote:   
   >> On Thu, 7 Apr 2011 15:21:49 -0700 (PDT), Father Haskell   
   >>   
   >>  wrote:   
   >> >1095, or whatever alloy old files are made from.  Making a   
   >> >small wood carving drawknife from an old 8" mill file, tempering   
   >> >with the kitchen oven.  Sites recommend 400F for 20 minutes   
   >> >or so to get a good edge-holding Rc60.  What they don't recommend   
   >> >is quenching once the blade is cooked.  Is simple air cooling by   
   >> >shutting off the oven sufficient to set the temper?   
   >>   
   >> If it is 1095 then it is hardened by heating to 1475F (800 C) and   
   >> quenching in water or brine. Thin sections may be quenched in a light   
   >> oil to avoid cracking. You can reach R66 in the hardened condition.   
   >> Temper is from 700 to 1300 degrees depending on use. 1095 can reach   
   >> R55 at the lower temperature.   
   >>   
   >> If color hardening and tempering then heat to a "cherry red" and hold   
   >> for sufficient time for even heating throughout. Quench. Re heat to a   
   >> light yellow to deep blue depending on use - lighter color is harder   
   >> and more brittle - and usually quenched. If done in a temperature   
   >> controlled device the second quench is somewhat redundant although it   
   >> is usually done as a fail safe action if the item was not heated   
   >> evenly in the tempering cycle.   
   >   
   >Grinding to rough shape without annealing.  Slower, but the   
   >shape is already close to what I need (just needs the ends   
   >ground into tangs and the middle 2" lapped and beveled on   
   >one edge).  I should be able to skip the whole rehardening   
   >step and any associated risk of warping or cracking.   
      
      
   If it is as hard as you want then there is no need to re-harden/temper   
   if you are happy with it.   
   \   
   Re hardening: 1095 heat soaked at 1475 F long enough to ensure that   
   the item is completely heat soaked and quenched in room temperature   
   brine may well be so hard that it can crack just from the stresses set   
   up by the hardening process.   
      
   One method said to avoid this is to have a pot of boiling water handy.   
   Quench and then drop in boiling water long enough that it is   
   temperature soaked at 212 F. then temper.   
      
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