Description of S235JR (E235B) Square Steel Pipe S235JR (also designated as E235B under certain standards) is a non-alloy structural steel grade widely used in construction and engineering applications. Square steel pipes made from this material are popular due to their excellent mechanical properties, weldability, and cost-effectiveness. Below is a detailed overview of S235JR (E235B) square steel pipes, covering their composition, properties, applications, and advantages. 1. Material Composition and Standards S235JR is a European standard (EN 10025-2) carbon steel grade, while E235B is an older designation (EN 10025:1990). Both grades are equivalent in terms of chemical composition and mechanical properties. The steel contains low carbon content (≤ 0.17%) along with controlled levels of manganese, phosphorus, and sulfur to ensure good strength and ductility. The "JR" suffix indicates impact resistance at room temperature (minimum 27 Joules at 20°C). 2. Mechanical Properties - Yield Strength (ReH): ≥ 235 MPa - Tensile Strength (Rm): 360–510 MPa - Elongation (A5): ≥ 26% (for thicknesses ≤ 16 mm) - Impact Toughness: Meets Charpy V-notch requirements at 20°C These properties make S235JR square pipes suitable for load-bearing structures where moderate strength and good formability are required. 3. Manufacturing Process Square steel pipes are typically produced through: - Cold-forming: Flat steel strips are roll-formed into a square shape and welded longitudinally (ERW process). - Hot-rolling: Used for thicker-walled pipes, providing better dimensional stability. The pipes undergo surface treatments (e.g., galvanizing, painting) to enhance corrosion resistance if required. 4. Applications S235JR square steel pipes are widely used in: - Construction: Frames, supports, and trusses in buildings and bridges. - Infrastructure: Guardrails, signposts, and street furniture. - Industrial Equipment: Machinery frames, conveyor systems, and storage racks. - Furniture and Decoration: Modern furniture, exhibition stands, and architectural designs. Their square shape offers advantages in ease of assembly, aesthetic appeal, and efficient space utilization compared to round pipes. 5. Advantages - Weldability: S235JR steel is easy to weld using common methods (MIG, TIG, arc welding) without preheating. - Machinability: Can be cut, drilled, and bent with standard tools. - Cost-Effectiveness: Provides a balance between performance and affordability. - Durability: Suitable for both indoor and outdoor applications when properly coated. 6. Surface Quality and Finishes Standard finishes include: - Black (untreated): Economical but requires additional protection in corrosive environments. - Galvanized: Zinc-coated for enhanced rust resistance. - Painted/Powder-Coated: Custom colors for aesthetic or protective purposes. 7. Compliance and Certifications S235JR square pipes comply with EN 10219 (cold-formed welded structural hollow sections) or EN 10210 (hot-finished hollow sections). They may also meet ASTM, ISO, or other regional standards depending on customer requirements. Conclusion S235JR (E235B) square steel pipes are versatile, reliable, and widely used in structural and decorative applications. Their combination of strength, weldability, and affordability makes them a preferred choice for engineers and fabricators. Proper selection of thickness, surface treatment, and manufacturing standards ensures optimal performance in various environments. (Word count: 500)