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Table of Contents
Introduction: Q235 Steel and S355 Steel
Q235 steel
Q235 steel is a kind of normal carbon structural steel, widely used in China. It is also called Q235A, Q235B, Q235C and Q235D. Because Q235 steel is mild carbon steel, it can be used for production without heat treatment. Q is for yield point, 235 is for yield strength. Q235 steel has good plasticity and weldability.
S355 steel
S355 steel is an Europe standard low alloy high strength structural steel, S means structural steel, its yield strength is not less than355Mpa. It has good mechanical properties, weldability and certain corrosion resistance, widely used in manufacturing construction, machinery manufacture, petrochemical, shipbuilding and marine engineering.
Chemical Components: Q235 Steel and S355 Steel
In GB/T 700-2006 standard, Q235 is divided into A B C D grade according to metallurgical quality, the chemical components of each grade are as follows:
Q235 grade A: C ≤0.22% Mn≤1.4% Si ≤0.35% S ≤0.050 P ≤0.045
Q235 grade B: C≤0.20% Mn≤1.4% Si ≤0.35% S ≤0.045 P ≤0.045 (With the consent of the customer, the carbon content may not exceed 0.22%)
Q235 grade C: C ≤0.17% Mn≤1.4% Si ≤0.35% S ≤0.040 P ≤0.040
Q235 grade D: C ≤0.17% Mn≤1.4% Si ≤0.35% S ≤0.035 P ≤0.035
The chemical composition of S355 steel is usually include C, Si, Mn, P and other elements, specific contents are as follows:
| C | Si | Mn | P | S | Cu |
| ≤0.22 | ≤0.55 | ≤1.6 | ≤0.025 | ≤0.025 | ≤0.55 |
Comparison of Q235 Steel and S355 Steel
Q235 steel and S355 steel are both common use structural steel, but they are differ from the chemical components and mechanical properties.
Q235 Steel
Q235 is a kind of common carbon structural steel, its tensile strength is about 235Mpa, the yield strength will reduce along with the increase of the steel thickness. Q235 steel has good plasticity, toughness and weldability, widely used in building structures, bridges, towers, containers and other structural parts. The chemical components of Q235 steel mainly include C, Si, Mn, S, P and other elements.
Different grades of Q235 steel are different in impact test temperature and chemical components. For example, Q235 grade A don’t do impact test, Q235 grade B do impact test at room temperature, Q235 grade C do impact test at 0℃, Q235 grade D do impact test at -20℃, Q235 grade E do impact test at -40℃. The carbon content of Q235 steel generally between 0.14%-0.22%, with good weldability, suitable for the use of welded structures.
S355 Steel
S355 steel is a kind of low alloy high strength structural steel, its yield strength is not less than 355Mpa, has higher strength and hardness than Q235 steel, while maintaining good weldability and impact toughness. S355 steel is widely used in bridge, vehicle, ship, construction, pressure container, special equipment etc. The chemical components of S355 steel include C, Si, Mn, P, S etc. The carbon content generally no more than 0.22%, Mn no more than 1.60%, the composition of P and S also low to ensure the weldability and impact toughness of the material.
Different quality grade of S355 steel ( S355JR, S355J0, S355J2 etc.) mainly distinguished according to the temperature of the impact testing and impact absorption energy. For example, S355J2 specification requires impact testing at -20℃, with a minimum impact absorption energy of 27J.
Conclusion
In conclusion, S355 steel has higher yield strength and better mechanical properties than Q235 steel, and is suitable for structures and components with higher strength requirements. Q235 steel is also very common in many structural application because of its good processing performance and economy. When choosing steel, it is necessary to decide which material to use according to the specific application requirements and the cost.
FAQ
What is the main difference between Q235 steel and S355 steel?
Q235 steel is a normal carbon structural steel, while S355 steel is a low alloy high strength structural steel, the tensile strength of Q235 steel is 235 Mpa, while the tensile strength of S355 steel is not less than 355Mpa. S355 steel has higher strength and hardness than Q235 steel, with good weldability and impact toughness.
What is the chemical components difference between Q235 steel and S355 steel?
The mainly chemical components of Q235 steel include C, Si, Mn, S, P and other elements, in addition to these elements, S355 steel may include other alloying elements such as V, Ti, Nb etc. These elements can improve the strength and the toughness of the steel.
Comparison of mechanical properties of Q235 steel and S355 steel?
The mechanical properties of S355 steel are usually better than Q235 steel, including higher yield strength , tensile strength and impact toughness. S355 steel can remain good impact property under low temperature condition, it make S355 steel suitable for strict application scenario.
What does Q235 steel and S355 steel perform in terms of corrosion resistance?
S355 steel generally has better corrosion resistance than Q235 steel because it has more alloy elements. In some specific marine engineering applications, S355 steel may be a better choice, or Q235 steel could be given a special surface treatment to improve its corrosion resistance.
