All standard gages are manufactured from tool steel and hardened to 58 – 62 Rc
Chrome is a plating process that increases the hardness to 70-72 Rc. The Chrome process also reduces friction on the gage and prevents corrosion. There are many variables that effect gage life or wear but chrome can significantly extend the wear life of a gage by more than 100%. The typical cost to add chrome is usually 30% more than tool steel.
Carbide is a sintered metal with a harder but more brittle surface than chrome. The RC of carbide gages is 79-81 Rc.
Titanium Nitride (TiN) is a general-purpose coating for corrosion resistance and increased tool life. The Rc is approximately 85RC
When selecting alternate materials to tool steel it is important to consider the benefits to the additional cost.