S235 vs. S355

Attribute	S235	S355
Material Type	Structural Steel	Structural Steel
Yield Strength	235 MPa	355 MPa
Tensile Strength	360-510 MPa	470-630 MPa
Thickness	1.5-25 mm	1.5-25 mm
Applications	Construction, machinery, automotive	Construction, machinery, automotive

Introduction

When it comes to structural steel, two common grades that are often compared are S235 and S355. These grades are widely used in construction and engineering projects due to their excellent mechanical properties. In this article, we will compare the attributes of S235 and S355 to help you understand the differences between these two grades.

Chemical Composition

One of the key differences between S235 and S355 is their chemical composition. S235 has a minimum yield strength of 235 MPa and a tensile strength of 360-510 MPa. On the other hand, S355 has a minimum yield strength of 355 MPa and a tensile strength of 470-630 MPa. This difference in strength is due to the higher carbon content in S355, which provides greater strength and durability.

Impact Strength

Another important attribute to consider when comparing S235 and S355 is their impact strength. S235 has a minimum impact energy of 27 Joules at room temperature, while S355 has a minimum impact energy of 27 Joules at -20 degrees Celsius. This means that S355 is more suitable for applications that require high impact resistance, such as structural components in buildings or bridges.

Weldability

Weldability is another factor to consider when choosing between S235 and S355. S235 has good weldability, but S355 is known for its excellent weldability. This is due to the higher carbon content in S355, which allows for better heat treatment and welding processes. As a result, S355 is often preferred for applications that require complex welding techniques.

Corrosion Resistance

Corrosion resistance is an important attribute for structural steel, especially in outdoor or marine environments. S235 has moderate corrosion resistance, while S355 has better corrosion resistance due to its higher carbon content. This makes S355 a better choice for applications that are exposed to harsh weather conditions or corrosive environments.

Cost

Cost is always a factor to consider when choosing between different grades of steel. In general, S235 is more affordable than S355 due to its lower carbon content and lower strength. However, the cost difference may vary depending on the specific requirements of your project. It is important to consider the overall cost of the material as well as the long-term benefits of using a higher grade like S355.

Applications

Both S235 and S355 are versatile grades of structural steel that can be used in a wide range of applications. S235 is often used for general construction projects, while S355 is preferred for more demanding applications such as bridges, high-rise buildings, and offshore structures. The choice between S235 and S355 will depend on the specific requirements of your project and the level of strength and durability needed.

Conclusion

In conclusion, S235 and S355 are two popular grades of structural steel that offer different attributes and benefits. While S235 is more affordable and has good weldability, S355 offers higher strength, impact resistance, and corrosion resistance. The choice between S235 and S355 will ultimately depend on the specific requirements of your project and the level of performance needed. It is important to carefully consider the attributes of each grade before making a decision to ensure the success of your construction or engineering project.