This is a technique that can be used with any common welding process, MIG and TIG (with Stainless or other specialty filler wire), or Stick Welding, as you'll see I use Nickel-99 electrodes to. Considering its cost, relative ease of manufacture and thermal stability, this cast iron (particularly, gray cast iron), is actually a more specialized material for brake applications particularly the material of choice for almost all automotive brake discs. The low degree of shrinkage in gray cast iron makes it favorable for industrial engineering applications since it has a varied tensile strength range from less than 20,000 psi to over 60,000 psi, and hardness from 100 to 300 BHN (Brinell hardness number). Cast iron is an alloy material and is comprised of carbon, iron and silicon. It's formulated with shades which closely match original metal finishes. to as gray cast iron because of its characteristic color. There has been two class of cast irons historically, one having a gray fracture appearance and other having a white fracture appearance, named as gray cast iron and white cast iron respectively. 083 Cast Steel Up to 2 feet 2 feet to 6 feet over 6 feet 0.