When purchasing iron ingots, the most critical factor is the chemical composition, particularly the levels of Carbon (C), Silicon (Si), Manganese (Mn), Phosphorus (P), and Sulfur (S). For instance, Pig Iron typically contains 3.5% to 4.5% carbon. You must also specify the physical dimensions and weight per ingot (e.g., 5kg, 10kg, or 25kg) to ensure they are compatible with your induction furnace or foundry charging equipment. Always request a Mill Test Certificate (MTC) to verify that the batch meets ASTM or ISO standards.