S275JR steel plates are a cornerstone of modern structural engineering, offering a reliable combination of mechanical strength and practical versatility. Classified under the European standard EN 10025-2 as a non-alloy structural steel, S275JR is widely used in construction, manufacturing, and infrastructure projects due to its balanced properties. The designation "S275JR" breaks down as follows: "S" stands for structural steel, "275" indicates the minimum yield strength of 275 MPa (for thicknesses up to 16 mm), and "JR" denotes a Charpy V-notch impact test value of at least 27 Joules at room temperature (20°C). This makes it an ideal choice for applications requiring durability without excessive rigidity, allowing for efficient fabrication and cost-effective designs.
Key Properties of S275JR Steel Plates
S275JR is a low-carbon manganese steel, typically supplied in a hot-rolled, normalized, or as-rolled condition. Its composition and mechanical characteristics ensure good performance under load while maintaining ease of processing.
Chemical Composition
The chemical makeup of S275JR contributes to its weldability and toughness. Key elements include:
| Element | Typical Content (%) | Role in Steel |
|---|---|---|
| Carbon (C) | ≤ 0.21 | Provides basic strength; kept low to enhance ductility and weldability. |
| Silicon (Si) | ≤ 0.55 | Acts as a deoxidizer and improves oxidation resistance during processing. |
| Manganese (Mn) | ≤ 1.50 | Enhances strength, hardenability, and impact resistance. |
| Phosphorus (P) | ≤ 0.035 | Controlled to prevent brittleness. |
| Sulfur (S) | ≤ 0.035 | Minimized to improve ductility and reduce hot shortness. |
| Nitrogen (N) | ≤ 0.012 | Limited to avoid reducing toughness. |
| Copper (Cu) | ≤ 0.55 | Optional; aids in corrosion resistance if present. |
These values can vary slightly based on thickness and manufacturer, but they align with EN 10025-2 specifications. The low carbon equivalent (typically around 0.40) ensures excellent weldability without the need for preheating or post-weld heat treatment.
Mechanical Properties
S275JR strikes a balance between strength and formability, making it suitable for both static and moderate dynamic loads. Properties vary by thickness:
| Property | Value (for thickness ≤ 16 mm) | Value (for thickness 16-40 mm) | Notes |
|---|---|---|---|
| Yield Strength (ReH) | ≥ 275 MPa | ≥ 265 MPa | Minimum stress before permanent deformation. |
| Tensile Strength (Rm) | 410-560 MPa | 410-560 MPa | Ultimate stress the steel can withstand. |
| Elongation (A) | ≥ 23% (longitudinal) | ≥ 22% | Measures ductility; higher values indicate better formability. |
| Impact Toughness (KV) | ≥ 27 J at 20°C | ≥ 27 J at 20°C | Charpy V-notch test; ensures resistance to brittle fracture. |
| Hardness (Brinell) | ~120-150 HB | ~120-150 HB | Indicates machinability similar to mild steel. |
For thicker plates (up to 250 mm), yield strength may decrease slightly to 235 MPa, but the steel remains robust. Compared to higher grades like S355 (yield strength ≥ 355 MPa), S275JR offers lower strength but superior machinability and cost savings, while outperforming milder grades like S235 in toughness.
Physical Properties
Density: Approximately 7.85 g/cm³, standard for carbon steels.
Melting Point: Around 1,450-1,500°C.
Thermal Conductivity: 50-60 W/m·K, adequate for structural uses.
Modulus of Elasticity: 210 GPa, providing good stiffness.
These attributes make S275JR plates resistant to moderate environmental stresses, including vibration and impact, without requiring specialized treatments.
Balancing Strength and Versatility
The hallmark of S275JR steel plates is their ability to deliver sufficient strength for load-bearing applications while offering high versatility in fabrication. With a minimum yield strength of 275 MPa, it supports heavy structures like buildings and bridges without being overly brittle or expensive. Its low carbon content (≤ 0.21%) ensures excellent ductility (elongation >20%), allowing the plates to deform under stress rather than fracture, which is crucial for safety in seismic or dynamic environments.
Versatility shines in processing:
Weldability: No restrictions; compatible with common methods like SMAW, GMAW, and FCAW. The low carbon equivalent prevents cracking.
Formability: Easily bent, rolled, or cold-formed, ideal for custom shapes in machinery or architectural elements.
Machinability: Comparable to mild steel, enabling efficient drilling, cutting, and profiling with standard tools.
Surface Finishes: Available hot-rolled, shot-blasted, primed, or galvanized for enhanced corrosion resistance in outdoor uses.
This balance reduces material costs (often 20-30% less than higher-strength alloys) and minimizes waste through non-standard sizing options. However, for extreme conditions like high corrosion or ultra-high loads, variants like S275J2 (impact-tested at -20°C) or S275JR with weathering additions may be preferred.
Applications of S275JR Steel Plates
S275JR's properties make it a go-to material across industries, from general construction to specialized engineering:
Construction and Infrastructure: Beams, columns, and frames for buildings, warehouses, shopping malls, and bridges. Its load-bearing capacity supports multi-story structures while allowing easy on-site assembly.
Machinery and Equipment: Components like shafts, bushings, axles, and frames for cranes, excavators, dump trucks, and agricultural machinery. The impact resistance handles vibrations and shocks.
Transportation: Rail wagons, trailers, shipbuilding elements, and offshore platforms. Used in oil and gas for penstocks and storage tanks due to its formability.
Mining and Energy: Plates for mining equipment, power plant structures, and wind turbine bases, where moderate strength and weldability are key.
Other Uses: Automotive parts, yellow goods (e.g., bulldozers), and general fabrication like storage facilities or conveyor systems.
In practice, S275JR plates are often flame-cut or profiled for precision fits, with thicknesses ranging from 3 mm to 250 mm and widths up to 3,500 mm. Its global availability and compliance with standards like BS EN 10025 ensure seamless integration into international projects.
Equivalents and Comparisons
S275JR has equivalents in various standards, facilitating global sourcing:
| Standard | Equivalent Grade | Notes |
|---|---|---|
| ASTM | A36, A283 Gr. D | Similar yield strength; A36 has slightly higher carbon for better weldability in some cases. |
| JIS | Ss400 | Comparable mechanical properties; widely used in Asia. |
| DIN | St44-2 | Older German designation with matching composition. |
| GB | Q275B | Chinese equivalent for structural uses. |
| IS | Fe410WA | Indian standard for mild structural steel. |
Compared to S355J2-steel_4448.html target=_blank class=infotextkey>S355JR, S275JR has lower strength but better formability and lower cost, making it preferable for non-critical applications. Versus S235JR, it offers higher toughness for demanding environments.
Conclusion
S275JR steel plates exemplify the perfect balance of strength and versatility, providing engineers with a dependable, cost-effective material for diverse structural needs. Its robust mechanical properties, ease of fabrication, and wide applicability make it indispensable in construction, manufacturing, and beyond. For projects requiring enhanced impact resistance or corrosion protection, consulting specific variants or coatings is recommended. Sourcing from certified suppliers ensures compliance with EN 10025-2, guaranteeing performance and safety.
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