No matter how good your steel is, if the heat treat sucks, then at best you won’t be enjoying the full potential of that premium steel you paid for, and at worst it will perform almost no better than a mass produced, big box blade. The heat treat needs to hit the sweet spot between being hard (good edge) and too hard (brittle), as well as having a bit of flex for strength and shock absorption. Many
modern heat treats aim to achieve a single, uniform hardness throughout the blade, and run the gamut between hard and too hard by being just hard enough. This allows them to hold a decent edge without too much risk of chipping or breaking under normal use.
Then there’s something called
differential hardening. The basic idea behind this heat treat is that the edge and ground portion of the blade is harder than the back or “spine” of the blade. This heat treat method was developed by
Japanese sword-makers hundreds of years ago, and it allows a skilled maker to harden a blade’s edge several
Rockwell C points more, taking a “hard enough” edge to a
razor sharp edge. Then, to avoid making the blade brittle as a result, the spine is tempered several points softer, which creates a blade that is
tough, shock resistant and has some flex. A quality heat treat is more than important; it will elevate a good steel into the best blade that it can be.