Description
S275JR Structural Steel & Steel Plate: Comprehensive Guide
Table of Contents:
- Introduction to S275JR Structural Steel
- Chemical Composition of S275JR Steel
- Mechanical Properties of S275JR
- Yield Strength
- Tensile Strength
- Elongation
- Impact Resistance (JR designation)
- Manufacturing and Processing of S275JR Steel Plates
- Hot Rolling Process
- Heat Treatment
- Standards and Compliance for S275JR Steel
- EN 10025-2 Standard
- International Standards
- S275JR Steel Plate Grades
- S275JR
- S275J0
- S275J2
- Applications of S275JR Structural Steel
- Building Construction
- Infrastructure (Bridges, Railways)
- Mechanical Engineering
- Offshore and Marine Projects
- Weldability and Formability of S275JR Steel
- Comparison of S275JR with Other Structural Steel Grades
- S235 vs. S275JR
- S275JR vs. S355
- Conclusion: Why Choose S275JR for Your Project?
1. Introduction to S275JR Structural Steel
S275JR is a popular grade of low-carbon structural steel that is widely used in construction and engineering projects. It is part of the European standard EN 10025-2, which specifies technical delivery conditions for non-alloy structural steels. The designation “S275” represents a minimum yield strength of 275 MPa (megapascals), while “JR” indicates that the steel has undergone a Charpy impact test at room temperature (20°C), ensuring a certain level of toughness and impact resistance.
S275JR is versatile and cost-effective, offering an excellent balance between strength, ductility, and ease of fabrication. It is particularly well-suited for structural applications where moderate strength and good weldability are required.
2. Chemical Composition of S275JR Steel
The chemical composition of S275JR steel plays a vital role in its mechanical properties. The primary elements in S275JR steel include:
- Carbon (C): Max 0.25%
- Manganese (Mn): Max 1.5%
- Phosphorus (P): Max 0.045%
- Sulfur (S): Max 0.045%
- Silicon (Si): Max 0.3%
The relatively low carbon content in S275JR ensures that the steel remains ductile and easy to weld, while manganese improves its strength and toughness. The careful control of sulfur and phosphorus content helps prevent brittleness.
3. Mechanical Properties of S275JR
3.1 Yield Strength
- Minimum Yield Strength: 275 MPa The yield strength of S275JR makes it suitable for load-bearing applications in construction and other fields where the steel must withstand a specific load before it begins to deform.
3.2 Tensile Strength
- Tensile Strength: 410-560 MPa This wide range of tensile strength ensures that S275JR can handle various stresses and strains, making it versatile for multiple structural applications.
3.3 Elongation
- Elongation at Break: 23% (for a thickness of ≤ 16mm) The steel’s ability to stretch before it breaks ensures that it has good ductility, a vital property for structural materials that need to absorb shock and resist cracking under stress.
3.4 Impact Resistance (JR Designation)
The “JR” designation in S275JR indicates the steel’s ability to withstand impact forces. It undergoes a Charpy V-notch test at 20°C, where it must achieve a minimum impact energy of 27 Joules, ensuring its toughness in ambient temperature conditions.
4. Manufacturing and Processing of S275JR Steel Plates
4.1 Hot Rolling Process
S275JR steel plates are typically produced using the hot rolling process, where the steel is heated above its recrystallization temperature and then rolled into plates. This process ensures a uniform thickness and a fine grain structure, which enhances the steel’s mechanical properties.
4.2 Heat Treatment
S275JR steel can also be subjected to various heat treatment processes, such as normalizing or quenching, to improve its mechanical properties further. However, in most cases, the steel is used in its as-rolled condition, which provides a good balance of strength and ductility.
5. Standards and Compliance for S275JR Steel
S275JR steel is manufactured in compliance with several standards, ensuring its suitability for various applications. The most important standard for this steel is:
- EN 10025-2 Standard: This European standard outlines the delivery conditions for non-alloy structural steels, including S275JR. It covers aspects like chemical composition, mechanical properties, and dimensional tolerances.
In addition to EN 10025-2, S275JR also complies with several international standards, making it suitable for use in projects around the world.
6. S275JR Steel Plate Grades
S275JR is part of the S275 family, which includes other grades with varying impact resistance and mechanical properties:
6.1 S275JR
- Impact-tested at 20°C
- Minimum yield strength of 275 MPa
- Used in standard structural applications
6.2 S275J0
- Impact-tested at 0°C
- Suitable for environments where lower temperatures are a factor
6.3 S275J2
- Impact-tested at -20°C
- Used in applications where higher toughness is required, especially in cold climates
7. Applications of S275JR Structural Steel
S275JR steel is widely used in a variety of industries and applications due to its excellent strength and versatility:
7.1 Building Construction
S275JR is commonly used in the construction of buildings, both residential and commercial. Its strength and good weldability make it ideal for beams, columns, and other load-bearing components.
7.2 Infrastructure (Bridges, Railways)
S275JR is frequently employed in the construction of bridges and railway infrastructure. Its ability to withstand moderate loads and impact forces ensures the structural integrity of these critical projects.
7.3 Mechanical Engineering
S275JR steel plates are used in the fabrication of various mechanical parts and components in machinery. The steel’s balance of strength and formability makes it ideal for this sector.
7.4 Offshore and Marine Projects
S275JR’s good toughness and ability to withstand impact forces make it suitable for offshore structures, such as oil platforms and marine vessels, where the steel may be subjected to harsh environmental conditions.
8. Weldability and Formability of S275JR Steel
One of the significant advantages of S275JR steel is its excellent weldability. The low carbon content allows for easy welding using standard methods, such as arc welding and gas welding. This makes it suitable for on-site fabrication, reducing the need for specialized welding techniques.
In terms of formability, S275JR can be easily shaped and bent without compromising its mechanical properties, making it ideal for projects where complex structural components are required.
9. Comparison of S275JR with Other Structural Steel Grades
9.1 S235 vs. S275JR
- S235 has a lower minimum yield strength (235 MPa) compared to S275JR (275 MPa). S275JR offers better mechanical properties and is typically used in more demanding structural applications.
9.2 S275JR vs. S355
- S355 is a higher-strength grade, with a minimum yield strength of 355 MPa. It is used in applications requiring greater load-bearing capacity. However, S275JR is more cost-effective for projects where high strength is not the primary concern.
