400 degrees should be sufficient to temper the steel, 01 is commonly drawn to temperatures between 350-450 degrees and acheives a Rockwell hardness of around 60-63 at this range. I should clarify the time frame we use though. Since we typically are working with relatively small parts an hour at 400 is usually sufficient. Rule of thumb states that you should go one hour for each inch of maximum thickness of the part, I suppose a shotgun action would require 2-3 hours at that temp if you wanted to acheive the same effect. We have a Rockwell hardness testing machine in the lab, but casehardened surfaces are not that easy to check since the diamond just wants to break through the case into the softer section underneath. Comparison testing with a file definitely shows that the tempering operation softens the outer surface however. I still contend that its primary importance is for appearances though, it tends to bring out the colors and they always look better, in my opinion, after this operation.
You got nice colors on your action. I would suspect the plates you have help to contain the charcoal around the action during the quench, you get pretty much the same results with blocking. I've noticed, when using blocking, that the colors are generally better towards the side that the blocking plates are on. We use simliar methods for the parts we do in our lab, we have also had very good luck building fixtures that project out the bottom of the pack and enter the water first, I think this has the tendency to cause the water to be displaced and than it suddenly rushes in on the parts and creates very dramatic colors. Lots of possiblities with this process and it is always neat to see other peoples results.
Last edited by Alex Johnson; 09/11/08 09:33 PM.
