Support BladeForums! Paid memberships don't see ads! From what I have read, 1075 or 1084 would be the best as they have the easiest heat treatment for low cost high carbon steels. An oil quench is recommended for them. 1055 is used for axes so it should make durable thrower but it could be tough finding it in the thickness and width that you want. You could grind a knife out of a file or rasp and then temper it back to gain toughness assuming it isn't case hardened.