The article says it has high toughness even when it’s very hard, and that at a somewhat lower hardness it should be really tough (close to 80crv2 on the graph). I guess we’ll see!
apexultra seems to get around 10 ft-lbs at 65... but isn't tested to lower hardness
while 80crv2 is 30 ft-lbs at 61 hrc
I'd love to see how tough it could get... if anyone has tested at lower hrc, please share results : )