Falanx

Incorrect. Hardness and toughness, while inversely related, are inversely related within a given composition of steel. Comparing two substantially different steels by a single mechanical property is fallacious. The S series steels are shock steels. They were developed specifically to have higher toughness at any given hardness than other steels, often to the detriment to their peak hardness. S series steels won't reach 60Rc without water quenches, and industry avoids water quenches if it can, for understandable reasons. But S series steels will reach Charpy V notch impact energies well in excess of 60 joules, which 6150 at that hardness won't, even with very devout prayer. S2 steel is becoming the choice of almost all manufacturers of hand tools in place of 6150 (CrV) steel because it outperforms it in all metrics and isn't any more expensive to the toolmaker by a meaningful margin. The reason it's a new thing is that historically the UK especially, hasn't used the AISI S series steels because, well, we're idiots. They're well established in the US and Australia, and have equivalents in the Pacific rim, Russia and continental Europe, who all also use the L series steels too. * * * On the subject of heat treatment of these steels, they will be performed to given industry standards per alloy system. There will be very little difference between the performance of the same steel itself in bits by any manufacturer. What will matter more is how much attention is given to head forming - such as more complete filling of the screw inset, or an additional diamond dust coating applied to the rebates of the head