JIS G3101 — Rolled steel for general structures
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 hot-rolled steel for general structural use, covering steel plates, sections, bars, and strips. It is classified into four grades according to strength, from SS330 to SS540, and is delivered in hot-rolled condition. The standard mainly specifies tensile properties and upper limits for impurities such as phosphorus and sulfur. It has relatively lenient requirements on chemical composition, offering moderate strength, good machinability, and good bolting performance. It is suitable for general load-bearing and non-load-bearing structures where weldability is not a special requirement.
Typical applications
Widely used in general building structures, mechanical equipment frames, secondary bridge components, factory and warehouse skeletons, and other general steel structures, with SS400 being the most common. It is also used for supports, bases, connectors, and platforms. Due to its moderate strength, good formability and cutting performance, and economical price, it is suitable for conventional structures and manufacturing applications where bolting or riveting is the primary method and weldability and low-temperature toughness are not particularly important.
