I dunno how to post something with both print & photographs. Email me & I will send you a copy by return email.
Here are a couple selected portions:
Heat treating of steel has been done since ancient times—the Greek poet Homer refers to steel heat treat procedures in the Odyssey. You might want to read what Homer has to say about Ulysses’ treatment of the Cyclops. Also, the contest that Ulysses won when he finally returned home. Homer does have a couple of things to say about metals. In spite of your high school English teacher’s best efforts, he can be interesting.
To make that hardened piece of steel a little tougher, we reheat it just a few hundred degrees. That reheat, or “temper”, might be anywhere from 350°F/177°C (the temperature Mom bakes her apple pie) up to 1100°F (around 600°C) or so, hotter than her self-cleaning oven. The old word for temper was “draw”, and you will still hear heat treaters use this term, such as when referring to the “draw furnace”. The higher the tempering temperature, the softer the metal. We really don’t want the metal to be softer, but we have to accept it being softer if we want it tough enough to be useful for anything other than a file. One may also make truck springs of 1095. These are tempered close to 800°F (427°C), or until the hardness drops to about Rockwell C 40 to 45. That is a good “spring temper”.
The frizzens (hammers, more correctly) of flintlocks were “steeled” by forge welding or brazing a piece of steel onto a wrought iron part. When that steel wore out it could be replaced by another piece, brazed on. I examined two original American flintlock rifles and a Ryan & Watson brass barreled pistol, all three with a flat piece of steel brazed to the iron hammer. On the Ryan & Watson the steel is about 40/1000” (1 mm) thick.
To color case-harden an investment cast 8620 patent breech, it should be done at
the lowest temperature. That is 1320—1337°F (715—725°C) in Gaddy’s article. Consider letting the pack cool a bit lower, perhaps to 1200°F (650°C). before dumping into the quench. Quenching from a lower temperature helps keep the 8620 core from getting too hard.
Personally, I would prefer a breech filed out of annealed 1018 mild steel to any casting.
It would be good for life & limb to reserve color case hardening for plain, low-carbon steels only, and not ever for modern breech-loading rifle actions or revolver frames. It is not only to make their lawyers happy that firearms manufacturers attempt to discourage re-heat treating their products.
