Q245R steel and Q235B steel difference

Q245R steel and Q235B steel are two different materials commonly used in Chinese standards, and the main differences are as follows:

1. Material grade and standard:
Q245R steel: belongs to the pressure vessel steel, its grade is determined according to the GB 713-2014 standard.
Q235B steel: belongs to the general structural steel, its grade is determined according to the GB/T 700-2006 standard.

2. Chemical composition:
- Q245R steel: Carbon content (C) is usually between 0.20% and 0.25%; Silicon (Si) content is about 0.20% to 0.35%; Manganese (Mn) content between 0.40% and 0.60%; Phosphorus (P) content does not exceed 0.035%; Sulfur (S) content does not exceed 0.040%. In addition, it also contains trace alloying elements such as niobium (Nb), vanadium (V) and titanium (Ti).
- Q235B steel: Carbon content (C) is usually between 0.12% and 0.20%; Silicon (Si) content is about 0.30%; Manganese (Mn) content between 0.30% and 0.70%; Phosphorus (P) content does not exceed 0.045%; Sulfur (S) content does not exceed 0.045%.

3. Mechanical properties:
Q245R steel: has a high yield strength (usually above 245MPa) and tensile strength (usually between 400-520MPa), as well as good toughness and impact toughness. It is suitable for the manufacture of high temperature and high pressure pressure vessels, such as boilers, storage tanks, etc.
Q235B steel: has a relatively low yield strength (about 235MPa) and tensile strength (usually between 375-500MPa), which is lower than Q245R steel. Q235B steel is widely used in general structural parts, Bridges, buildings and so on.

4. Heat treatment:
Q245R steel: Heat treatment processes such as normalizing and controlled cooling can be carried out to obtain the required mechanical properties, especially to improve its toughness and impact toughness.
Q235B steel: under normal circumstances, no heat treatment is required, and can be used directly.

In summary, Q245R steel and Q235B steel have obvious differences in chemical composition, mechanical properties and uses. The selection of suitable materials should be evaluated and selected according to the specific application scenarios and requirements.

Pre: Corrosion resistance and oxidation resistance of 15CrMo steel

Next: Details of the weldability of 15CrMo steel