JIS G3101 — General structural steel
Grades
SS330, SS400, SS490, SS540
Chemical composition and mechanical properties
| Grade | Chemical composition | Mechanical properties |
|---|---|---|
| SS330 | C≤0.30 (>100mm≤0.40), Mn (no requirement), P≤0.050, S≤0.050 | Rm ≥330 MPa, Rp0.2 ≥205 MPa, A≥26% (for steel plates ≥25%) |
| SS400 | C≤0.30 (>100mm≤0.32), Mn (no requirement), P≤0.050, S≤0.050 | Rm 400-510 MPa, Rp0.2 ≥245 MPa, A≥23% (steel plate ≥21%) |
| SS490 | C≤0.30 (>100mm≤0.33), Mn≤1.60, P≤0.040, S≤0.040 | Rm 490-610 MPa, Rp0.2 ≥285 MPa, A≥20% (steel plate ≥19%) |
Application scope
JIS G3101 specifies general structural hot-rolled steel sections, covering H-beams, I-beams, channel steel, and angle steel, etc., classified into four grades from SS330 to SS540 according to strength, and delivered in hot-rolled condition. The standard mainly specifies tensile properties and upper limits for phosphorus and sulfur, with relatively lenient requirements on composition. These sections offer moderate strength, good machinability, and good bolting performance, making them suitable for general load-bearing structural components where weldability is not a special requirement.
Typical applications
Widely used in general building structures, mechanical equipment frames, secondary bridge components, factory skeletons, and other general steel structures, various types of steel can be combined to form beams, columns, and supports, with SS400 being the most commonly used. It is also used for components such as supports, connectors, and platforms. Due to its moderate strength, good formability and cutting performance, and economy, it is suitable for conventional structural applications where bolts or riveting are the primary methods and weldability is not a special requirement.
