CAST IRON: Lower melting point, greater fluidity than steel. 97% iron, 2% carbon, 1% manganese and silicon. What makes iron special is its high (highest) nucleonic binding energy.
CARBON STEEL: Typically 90+% iron, 2% carbon, the remainder various quantities of cobalt, molybdenum, niobium, tungsten, vanadium, zirconium, chromium, nickel, copper, manganese, phosphorous, sulfur, or silicon. Machine stamped from sheet.
STAINLESS STEEL: (Austenitic) Perhaps 50% iron with high quantities of chromium, nickel (20-25% each), other trace metals.
ALUMINUM ALLOY: 3xxx alloy of usually about 97-98% alumina, with traces of copper, iron, manganese, silicon, zinc and other metals.