Is S275JR Structural Tube Stainless Steel?
No. S275JR is a non-alloy structural carbon steel, not a stainless steel. The JR designation in EN 10025-2 refers to a specified minimum Charpy impact energy of 27 J at room temperature, while 275 states the minimum yield strength in megapascals. S275JR structural tube is used for general structural and mechanical fabrication and does not contain the chromium levels that define stainless steel, so it offers no inherent stainless corrosion resistance and normally requires protective coating for outdoor service.
Chemical Composition
The composition of S275JR is controlled by the product thickness. The commonly published maximum values for material up to 40 mm thick are shown below.
| Element | Maximum Content (%) |
|---|---|
| Carbon (C) | 0.21 |
| Manganese (Mn) | 1.50 |
| Phosphorus (P) | 0.035 |
| Sulfur (S) | 0.035 |
| Nitrogen (N) | 0.012 |
Mechanical Properties
The key mechanical properties of S275JR are listed below.
| Property | Requirement |
|---|---|
| Minimum yield strength | 275 MPa |
| Tensile strength | 410 - 560 MPa |
| Elongation, min | 21% |
| Charpy impact energy, min | 27 J at room temperature |
Key Features
S275JR combines moderate strength with good plastic deformation capacity, so it performs well under impact and dynamic loads without brittle fracture at normal service temperatures. It welds reliably with standard processes and consumables, producing sound joints with minimal risk of cracking, which keeps fabrication simple and economical. Its ductility allows cold bending, forming and hole punching without difficulty, and structural hollow sections are readily available with square, rectangular and circular cross-sections.
Corrosion Behaviour and Protection
Like other structural carbon steels, S275JR has only limited resistance to atmospheric corrosion. For exterior use, hot-dip galvanizing, painting or powder coating should be specified according to the environment and design life. In aggressive or wet environments, weathering steel or coated systems should be considered instead of relying on the bare material.
Typical Applications
S275JR structural tube is used in building frames, roof trusses, bridges, platforms, gantries, vehicle and trailer frames, agricultural machinery, storage racking and general steel fabrications. It is also a common material for welded assemblies where the engineer requires a certified, predictable structural grade.
Frequently Asked Questions
Is S275JR stainless steel?
No. S275JR is a non-alloy structural carbon steel defined in EN 10025-2. It contains no significant chromium and is not corrosion resistant like stainless steel.
What does JR mean in S275JR?
JR indicates a minimum Charpy impact energy of 27 J at room temperature, providing a basic level of toughness assurance for structural applications.
What is the yield strength of S275JR?
The minimum yield strength is 275 MPa for thicknesses up to 16 mm, with slightly reduced values for thicker material as defined in EN 10025-2.
Can S275JR be galvanized?
Yes. Hot-dip galvanizing is a common and effective protection method for S275JR structural tube used outdoors.
What is the difference between S275JR and S355JR?
Both are EN 10025-2 structural steels, but S355JR has a higher minimum yield strength of 355 MPa, achieved by higher manganese content, and is used where higher load capacity is required.