Originally Posted by
ChrisMeyer
I have watched Kevin Cashen (MS) perform interrupted quenchs on 1084 blades on several occasions. The technique works (I have used it myself) and has several benefits; chiefly, it allows you a chance to correct any warping and gives a sort of auto temper to the blade. As part of his heat treating demonstrations, Kevin will often bend the blade as he pulls it out of the interrupted quench, then straighten it again before the blade fully hardens.
When you are heat treating a blade, you heat it to the proper temperature for the steel, soak at temperature, then quench the blade. Once the temperature of the blade has dropped sufficiently fast enough to beat the Pearlite nose on the TTT chart, it will form Martensite as it cools to room temperature. The speed with which it achieves room temperature is not critical (unless you prevent it), and slower speeds are less stressful on the blade.
When you are interrupting a quench, you are usually trying to remove your blade when it gets to about 400 degrees F. Then, as it cools it gives an auto temper to the blade and makes the blade less likely to crack before you can get it into a tempering oven.
I'm sure Kevin Cashen can explain this procedure and why it works much better than I, but it does work. I believe that Kevin has posted explanations on the BladeForums website. I'll try to post links later...