JIS SS400 angle steel is a type of structural steel recognized by the Japanese Industrial Standards (JIS). This grade of steel, SS400, is widely employed in various sectors due to its superior mechanical qualities and structural adaptability. SS400 angle steel typically comprises two legs linked at a perpendicular angle, giving an L shape. It is noted for its high tensile strength, weldability, and moderate hardness, making it ideal for construction, machinery production, and other structural applications. The "SS" in SS400 stands for structural steel, suggesting it is mainly used in building and construction.

JIS SS400 Angle Steel is available in various dimensions, with conventional sizes ranging from 20x20x3mm to 250x250x35mm and unequal angles ranging from 75x50x5mm to 150x100x12mm. These dimensions may differ based on the manufacturer and the specific requirements. Still, they generally follow the norms established by the Japanese Industrial Norms (JIS) for SS400 steel, a popular structural steel grade known for its strength and flexibility in building projects.

JIS SS400 Angle Steel is made mainly of iron and carbon, with trace amounts of manganese, sulfur, phosphorus, and silicon. Its carbon percentage ranges typically between 0.05% and 0.25%, making it a low carbon steel. Including manganese boosts its structural strength and toughness, while sulfur and phosphorus contribute to its machinability. Silicon aids in deoxidation and improves the steel's strength and durability. JIS SS400 Angle Steel is recognized for its moderate strength, weldability, and adaptability in various structural applications.