Thanks Madts. Now I can understand it.
Last year I tried to make a chipwood cutting knive for my own carving work out of an old metal HSS blade (about 64 Rockwell) The steel was to hard. A knive has to be thin and HSS is to hard and “crumbels”. That is why all knive tool makers using a carbon steel quality (mostly between 57 an 60 Rockwell) Carbon steel is more “flexible”

https://dutchypatterns.com/