If you look at White/Blue/Super funny they will rust. HAP40 is a high-speed tool steel. CPM M4 is a good comparison to it. MagnaCut will offer corrosion resistance that you don't tend to see in Japanese steels. MagnaCut will have better edge retention than White/Blue/Super. Those steels are low-alloy and rely on high hardness for wear resistance. MagnaCut has vanadium and niobium plus it can get pretty hard as well. MagnaCut is so far ahead of White/Blue/Super in this regard. Japanese steels are known for being great to sharpen (even HAP40). From what I have read, MagnaCut sharpens well.
If we say that MagnaCut = stainless 4V and HAP40 = CPM M4, then HAP40 should have some more edge retention but less toughness when compared to MagnaCut. The differences aren't all that great. Corrosion resistance is the real difference maker.
If we say that MagnaCut = stainless 4V and HAP40 = CPM M4, then HAP40 should have some more edge retention but less toughness when compared to MagnaCut. The differences aren't all that great. Corrosion resistance is the real difference maker.