Socket screw material alloying elements Manganese, Nickel, Chromium, Silicon, Titanium, Aluminium, Molybdenum, Vanadium and Copper can be added to steel to manipulate the steel's properties. The proportions of these elements will determine the properties of each socket screw alloy steel grade. When materials Molybdenum, Vanadium, Chromium or Nickel are added they create high strength steels and improve toughness; there is a high cost of adding these elements to the steel mix.
Along with Carbon and Alloy steel, there are Carbon-Boron steels. Small amounts of boron allow steels to be heat treated to high strengths without the cost penalty of other alloying elements, in many parts of the world there is widespread use of Boron steels for fasteners though there is some resistance in the USA because of historical failures. The properties of carbon-boron steels are not as good as alloy steels but they give a reasonable compromise between cost and improved properties benefits.