Induction hardening cleaver edge - GIF

[hemmjo]

Wouldn't the first several be harder than later ones as the water bath warms up? Maybe they use a refrigerated recirculation?

I do not think their greatest concern is quality control. This is certainly is not the ideal hardening process. The part is supposed to be swished around in the water to quench/cool it quickly. Not permitted to just sit there to cool slowly as the video shows.