UNS designations have been jointly developed by the Society of Automotive Engineers (SAE) and the American Society for Testing and Materials (ASTM). This system provides a uniform method of designating metallic materials by dividing metals and alloys into eighteen categories as shown in Figure 13. A UNS material designation starts with a single alpha character, which in many cases is suggestive of the family of metals it identifies; e.g., “A” indicates aluminum, “C” indicates copper, “N” indicates nickel, and “S” indicates stainless steel. Following the alpha character are five numeric digits, which likewise often suggest alloys within the family of metals; e.g., A92024 designates 2024 aluminum, C36000 designates copper alloy 360, S31600 designates type 316 stainless steel, and N04400 designates nickel alloy 400.
