Hello Mark,

I am not familiar with the Beta 1 hardening compound you plan to use, but the general principles of case hardening are to introduce additional carbon into the steel to a depth that is governed by the length of time the component is heated in contact with the compound.

Allowing it all to cool naturally still leaves the job soft and those areas which you wish to remain soft can then have the casing layer machined away.

After this, on reheating [with no more compound] to red heat and then quenching in water will leave the carbon rich surfaces glass hard. A softer quench can be into oil and the surfaces will still be hard but maybe 10 Rockwell points softer.

Now the component will need tempering to reduce the brittleness [certainly after water quenching] by careful and gentle re-heating to rapidly quench again into water when the tempering colour is as you want it. Straw is the hardest temper, dark blue the softest. For the hardest result boiling in water for perhaps 1 hour will still improve the resistance to cracking.

What you are doing here is also stress relieving and improving the fracture toughness by trading in some of the hardness imparted by the quench. Oil quenched parts may not need that treatment as the rate of cooling in oil is nowhere near as fierce.

I hope that answers your question.

Brian

Will you tell us how you got on with the beta CH powder ? If it worked out for you or not. I have heard since the 'elf and safety brigade meddled in the ingredients of case hardening powder it isn't so effective.