Lots of great info.
Doug, nice work as always.
Ill throw my two cents in, about all its worth...
From my point of view, annealing is a necessity, not only does it make the steel softer, but also burns off a lot of garbage on the steel; rust etc. Makes it so much easier to clean up.
Carbon in steel is cumulative, every time a part is case hardened, you are adding carbon, annealing helps diffuse the carbon into the steel.
There is a reason that many, if not most folks practicing CCH today are not doing true case hardening. True case hardening temps are high, I have original recipes from a couple of manufacturers, temps that they were using are in excess of 1600 deg F. Thats ok if you are a manufacturer, you can afford a certain percent waste but for the modern guy, working on someones pride and joy, or a one of one gun, you cannot afford to make mistakes, and you cannot afford to crack a frame. Youve got one shot to do it right. So most will safe side it.
In my mind, tempering after quench is an absolute must. It relieves strains in the metal, and, allows the metal to be tweaked slightly. Remember, when cases hardening you are changing the temperature of the steel by more than 1000 deg F. The steel is going to move, and more than likely, you will have to move it back. Tempering will allow you to do this with less likelihood of cracking. I generally temper around 400 deg F, with little to no change in coloration.
I know some folks will say that blocking will prevent this; it helps, but it does not prevent movement. I use blocks in certain areas, on more than once occasion I have watched the parts move after the blocks were removed. Now I always temper with blocks in place.
Mike
Great contribution Mike, thanks.
Any chance of a picture of an action with blocks in place? Are you recommending recoloring at lower temperatures, say around the 1333F temp that CS uses?
Regards,
Ken
