How to do Color Case Hardening

[TomG]

(11-17-2012, 04:07 AM)Harry Eales Wrote: Hello Tom,

One little tip here I wish to pass on. Now everyone who has worked with red hot metal knows that it gets a scale build up on all surfaces exposed to air.

When CC Hardening we don't want any of that happening to a polished part, do we? Now, no matter how careful you are in packing charcoal and bone into a crucible there will be air in the gaps between the grains of hardening compound.

The air can be eliminated simply by folding up a sheet of paper until it fits inside the top of the crucible beneath the lid. When the crucible heats up the paper will ignite, consuming the oxygen inside the crucible and what is left behind is carbon so there's no conflict likely it's simply adding to the carbon already present.

Harry

Hello Harry,

I had heard of that tip before to consume the oxygen, but thanks for reminding me.

Speaking of conflict, I got a message from a guy named Alex Johnson criticizing the Marlin thread for using a lower quench temperature. He pointed out that while it may lead to brighter colors, quenching below the critical temperature may not harden the part sufficiently. It's been a while since I've taken any classes in metallurgy, but he probably has a point. It sounds like some experimentation will be required.

Tom