Cast iron
Cast iron is made from pig iron, which is the product of smelting iron ore in a blast furnace. Cast iron can be made directly from the molten pig iron or by re-melting pig iron, often along with substantial quantities of iron, steel, limestone, carbon (coke) and taking various steps to remove undesirable contaminants. Phosphorus and sulfur may be burnt out of the molten iron, but this also burns out the carbon, which must be replaced. Depending on the application, carbon and silicon content are adjusted to the desired levels, which may be anywhere from 2–3.5% and 1–3%, respectively. If desired, other elements are then added to the melt before the final form is produced by casting.
Body piercing materials
316 stainless steel, also referred to as marine grade stainless steel, is a chromium, nickel, molybdenum alloy of steel that exhibits relatively good strength and corrosion resistance. Along with the titanium alloy Ti6Al4V, 316 stainless is a common choice of material for biomedical implants. Although Ti6Al4V provides greater strength per weight and corrosion resistance, 316 stainless components can be more economical to produce. However, immune system reaction to nickel is a potential complication of 316.[1][2] Implants and equipment that are put under pressure (bone fixation screws, prostheses, body piercing jewelry) are made out of austenitic steel, often 316L and 316LVM compliant to ASTM F138.[3] 316 surgical steel is used in the manufacture and handling of food and pharmaceutical products where it is often required in order to minimize metallic contamination. ASTM F138[3]-compliant steel is also used in the manufacture of body piercing jewellery[4] and body modification implants.