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X-WR-CALNAME:3/2014 Gil/hardening/tempering
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BEGIN:VEVENT
UID:31@cdblacksmiths.com
DTSTAMP:20140321T040000Z
SUMMARY:3/2014 Gil/hardening/tempering
URL:https://cdblacksmiths.com/news/3-2014-gil-hardening-tempering/
DTSTART;VALUE=DATE:20140421
DTEND;VALUE=DATE:20140422
DESCRIPTION:Write Up of the March 29\, 2014 CDBA Meeting by Jack Connell\
 n\nThis meeting had another good turnout which included members\, guests
 \, and greenhorns. Gil’s demo on the various aspects and steps towards
  hardening and tempering high carbon or tool steel (having at least 0.2%
  of carbon) was clear and informative. Gil initially demonstrated how st
 eel taken up to the point of being non-magnetic (1500 degrees +-\, or da
 rk yellow) when quenched too quickly is as brittle as a candy cane and w
 hen lightly tapped will snap in two. To move from this brittle state to 
 a useful one\, the steel needs to be "Tempered". Tempering relaxes the s
 teel and changes the interior crystal size from large\, brittle crystals
  to smaller more relaxed and stable ones. As Gil demonstrated\, this tem
 pering is done by taking the above heated steel and quenching the first 
 inch or so (pre-taper the edge\, assuming that you are making a chisel) 
 into the water quench (or could be oil\, depending on the ultimate use a
 nd/or steel type)\, swirl it around a bit and make sure you have suffici
 ently cooled this tip. Then withdraw the steel from the quench and quick
 ly\, while there is still most of the heat remaining in the shaft\, with
  a file or angle grinder\, polish one side of the cooled tip. This polis
 hed section is where you will see the various colors slowly moving towar
 ds the cooled tip edge\, the first color to show and move down to the ed
 ge is light straw followed by the other colors. Each color will represen
 t a degree of hardening. Once the wanted color/hardness is at or very cl
 ose to the cutting edge\, immediately quench the whole piece of steel ag
 ain to stop/arrest the color. Gil used a propane torch to get these colo
 rs. This is a simpler\, cleaner\, easier and more predictable way to con
 trol the heat transfer and helps insure that you can see and can stop th
 e color where and when you want it. The color chart and scale (the oxida
 tion color spectrum) that Gil showed is a real good tool to use to compa
 re the color of your work piece edge and thus the needed hardness. Gener
 ally\, the rule of thumb is that “straw” color will cut stone\; “B
 ronze” will cut steel\; “peacock” will cut wood\; and the color 
 “purple” will give the high carbon steel a “springiness” and fin
 ally\, “blue” will keep the steel relatively soft. Keep in mind that
  there are other methods of tempering\, but all have the essential ingre
 dients noted by Gil. We again thank Gil for sharing his knowledge and lo
 ok forward to him demonstrating again at another monthly meeting in the 
 near future. Speaking of which\, here is an updated monthly meeting sche
 dule. However\, as you can see\, we still have many gaps and need someon
 e to step forward to demonstrate (can be on anything related to steel 
 – this can mean even steel design / architecture demonstrated on paper
 ) for the months noted. Any volunteers please speak up! April 27: lee Ha
 rvey on bells May 18\; Noah Khoury on Dutch hinges June 29: ?? July 27: 
 Travis Edginton: Forging an axe head. August 24: Mark Feldman on casting
  September 28: Mike McCarthy at Mike Cataldo's forge: Finishing techniqu
 es October 26: Peter Schmidt on forging a very unique wine glass holder 
 which goes on a wine bottle. This is Pete's own design. November 23 (or 
 30th): ?? December 28: ??
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