49e56742   
   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.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)