S275JR is a versatile non-alloy (mild) carbon structural steel widely used in the construction and engineering industries. It is governed by the European standard EN 10025-2 and is known for its excellent weldability, formability, and machinability.
Breakdown of the Name "S275JR"
S: Denotes that it is a Structural steel.
275: Represents the minimum Yield Strength of 275 MPa (tested on material with a thickness ≤ 16mm).
JR: Indicates the quality grade related to impact resistance. Specifically, it has a minimum Charpy impact value of 27 Joules at room temperature (+20°C).
Key Characteristics
Weldability: Highly weldable due to its low carbon content (max 0.21–0.25% depending on thickness), requiring no preheating or special heat treatment for standard applications.
Formability: Suitable for cold forming, bending, and folding.
Durability: Offers good impact resistance, making it reliable for load-bearing structures.
Typical Applications
Construction: Framework for buildings, columns, and beams.
Infrastructure: Bridge building, trusses, and railings.
Manufacturing: Industrial machinery, storage tanks, and vehicle chassis.
International Equivalents
While standards vary, S275JR is often compared to the following regional grades:
USA (ASTM): ASTM A36 (often substituted for low-stress parts, though S275JR has a higher yield) or A529 Gr.D.
China (GB): Q275.
Japan (JIS): SS400.
Germany (DIN): St44-2.
UK (BS): 43A or 43B (now superseded by the EN standard).
Key Characteristics at a Glance
| Property / Designation | Specification |
|---|---|
| Standard | EN 10025-2 |
| Meaning of "S275JR" | S = Structural Steel 275 = Minimum Yield Strength of 275 MPa (for thickness ≤ 16mm) J = Impact toughness tested at Room Temperature (+20°C) R = Minimum impact energy of 27 Joules |
| Typical Tensile Strength | 410 - 560 MPa |
| Main Delivery Conditions | Hot-rolled (AR), Normalized (N), or Thermomechanically rolled (M) |
| Primary Advantage | Excellent weldability and formability, readily available, lower cost than higher grades. |
Comparison with Common Grades
It sits between the most common mild steel (S235JR) and the popular high-strength steel (S355JR) in terms of strength.
| Grade | Min. Yield Strength (MPa) | Typical Use Case |
|---|---|---|
| S235JR | 235 | Light structures, non-critical frameworks |
| S275JR | 275 | General construction, building frames, machinery bases, platforms |
| S355JR | 355 | Heavily loaded structures, cranes, vehicles |