Guide to Decoding Industrial Metal Symbols

Have you ever stared blankly at technical drawings filled with mysterious metal material codes like SS400, SUS304, or S45C? These seemingly cryptic combinations actually follow a logical system that reveals crucial information about the materials' properties and applications. Today we'll unlock the secrets of industrial metal classification systems.

In the vast world of materials, metals hold a dominant position due to their unique properties. To facilitate communication and standardization, engineers developed specialized classification systems. While these codes may appear complex at first glance, they follow consistent patterns that allow professionals to quickly identify a material's key characteristics.

According to JIS (Japanese Industrial Standards), metal materials are primarily divided into two categories:

• Ferrous Metals: Primarily iron-carbon alloys (steel), including structural steel, tool steel, and stainless steel with extremely wide applications.
• Non-Ferrous Metals: All metals and alloys excluding iron, such as aluminum, copper, magnesium, and titanium, each with distinct properties for specialized applications.

For easier comprehension, non-ferrous metals can be initially categorized into aluminum/aluminum alloys and copper/copper alloys, though the category includes many more materials.

Steel material symbols typically consist of three to four components, each conveying specific information about the material's composition and properties.

The initial letter represents the base material, usually derived from English names or chemical symbols:

• S: Steel
• F: Iron (Ferrum)

The second letter indicates the material's specification or intended use:

• S (SS400): General structural rolled steel (Structural)
• US (SUS304): Stainless steel (Use Stainless)
• TP (STPG): Pipe tubes (Tube Pipe)
• PH (SPHC): Hot-rolled steel plates (Plates Hot-rolled)

Numerical values typically represent mechanical properties like tensile strength or yield strength:

• 400 (SS400): Minimum tensile strength of 400MPa
• 304 (SUS304): Austenitic stainless steel grade in the 300 series

Additional letters may specify manufacturing methods or special treatments:

• -R: Rimming steel
• -A: Aluminum killed steel

• SS400: S (Steel) + S (Structural) + 400 (400MPa tensile strength) = Carbon structural steel with 400MPa tensile strength
• SUS304: S (Steel) + US (Stainless) + 304 (Grade) = Common austenitic stainless steel with excellent corrosion resistance
• SPHC: S (Steel) + PH (Hot-rolled plates) + C (General use) = Hot-rolled steel plate for general applications
• STPG: S (Steel) + TP (Pipe tubes) + G (General pressure) = Carbon steel pipes for general pressure applications

Mechanical structural carbon steels (e.g., S45C) follow a slightly different convention: S (Steel) + number (carbon content × 100) + C (Carbon). For example, S45C indicates steel with approximately 0.45% carbon content.

Similar to steel, non-ferrous metals follow their own standardized coding systems.

• C1***: Pure copper/high-copper alloys for electrical/anti-corrosion applications
• C2***: Copper-zinc alloys for decorative items and drawn products
• C3***: Copper-zinc-lead alloys for machined components like clock parts

• A1***: Pure aluminum for electrical busbars and reflectors
• A2***: Aluminum-copper-magnesium alloys for aerospace applications
• A3***: Aluminum-manganese alloys for building materials

While metal classification systems may initially appear complex, understanding their underlying logic makes material identification straightforward. The key lies in recognizing the pattern for steel, copper, and aluminum designations, supplemented by reference tables when needed.

Complete memorization isn't necessary—focus instead on grasping the fundamental principles and applying them in practical situations. The next time you encounter an unfamiliar material code, apply these decoding techniques to reveal its hidden meaning.