Since there's a large range of stainless there will be some that this fits for, but AUS 8 is used so often because it is a bit tougher than 440C, but 440C has slightly better corrosion resistance and has a bit more carbon. You can almost think of AUS 8 as 440B with some vanadium. The vanadium in AUS 8 helps with the toughness. The economics dictate why manufacturers use AUS8. From a metallurgical standpoint AUS8 and D2 aren't close enough to really be comparable since D2 will make a better blade if properly heat treated, but it isn't really a stainless (nearly, but not quite there).