What is the Difference Between Q235 and Q345?

Q235 and Q345 steel, as two main products in China’s steel industry, are closely linked to the prospects of the Chinese economy, industrial restructuring, technological advancement, and international market demand. While they may seem similar at first glance, they actually have distinct differences in material performance, chemical composition, and usage.

China's Steel Industry

Different Types of Steel Materials

Different Types of Steel Materials

Q235 Steel

Q235 steel is a type of common carbon structural steel. Because it is low-carbon steel, it does not require heat treatment during production. The “Q” stands for yield strength, and “235” represents the yield strength.

Q345 Steel

Q345 steel is a type of low-alloy steel, also known as Q345A, Q345B, Q345C, Q345D, and Q345E. It is a low-alloy steel (with C < 0.2%), where “Q” stands for yield strength, and “345” represents the yield strength.

 

Differences in Elemental Composition

Q345 Steel has higher manganese (Mn) and silicon (Si) content compared to Q235 Steel. Additionally, Q345 Steel has lower carbon content and higher alloy element content, thus giving it higher strength and corrosion resistance.

Q235 Steel

The carbon (C) content is less than 0.22%, manganese (Mn) content is less than 1.4%, silicon (Si) content is less than 0.35%, phosphorus (P) content is less than 0.045%, and sulfur (S) content is less than 0.045%.

Q345 Steel

The carbon (C) content is less than 0.20%, manganese (Mn) content is less than 1.7%, silicon (Si) content is less than 0.55%, phosphorus (P) content is less than 0.045%, and sulfur (S) content is less than 0.045%.

 

Yield Strength Difference

Yield Strength Difference

Q345 steel has better strength compared to Q235 steel.

Q235 Steel

The yield strength of Q235 steel is 235 MPa, with tensile strength ranging from 375 MPa to 500 MPa.

Q345 Steel

The yield strength of Q345 steel is 345 MPa, with tensile strength ranging from 490 MPa to 630 MPa.

 

Impact Temperature Difference

Due to its higher strength, the impact temperature of Q345 may be slightly higher than that of Q235. However, the specific impact temperature is still influenced by the processing and alloying conditions during the steel manufacturing process.

 

Welding Performance Difference

Welding Performance Difference

Due to the higher content of alloy elements in Q345 steel, its welding performance may be slightly inferior to that of Q235 steel. It requires more attention to welding processes to avoid welding defects or cracks.

 

Different Applications

Different Applications

Q235 Steel

Q235 steel has higher strength and good ductility, making it suitable for welding, cold bending, and forming processes. It is mainly used in general structural engineering, such as building frames, steel plates, steel pipes, etc.

Q345 Steel

Compared to Q235 steel, Q345 steel boasts higher strength, better corrosion resistance, and excellent ductility. It finds wide applications in areas such as bridges, building structures, and shipbuilding. Typically used in hot-rolled or normalized conditions, it can be employed in various structures in regions with temperatures below 40°C.

 

Price Difference

The price of Q235 steel is generally lower than that of Q345 steel, with a price difference of approximately 3% to 8%. This is because the production process and material costs for Q345 are relatively higher.

 

Conclusion

Conclusion

Q235 and Q345 steel, as primary products of China’s steel industry, have vast prospects for development both domestically and internationally. China stands as the world’s largest producer and consumer of steel, and the demand for Q235 and Q345 steel in international markets is also influenced by global economic conditions and trade environments. With the advancement of the Belt and Road Initiative and the facilitation of international trade, the competitiveness of Chinese steel products in the global market is expected to further strengthen.

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