Q235C steel plate is a commonly used carbon structural steel with clearly defined chemical composition and mechanical properties in the Chinese National Standard (GB). According to search results, the chemical composition of Q235C steel plate is specified in the GB/T 700-2006 standard, with a carbon content not exceeding 0.17%, manganese content not exceeding 1.4%, silicon content not exceeding 0.35%, phosphorus content not exceeding 0.040%, and sulfur content not exceeding 0.040%. These components give Q235C excellent plasticity, toughness, weldability, and cold stamping performance, making it suitable for manufacturing thin plates, steel bars, and various section steels for steel structures.

In the European Standard (EN), the material corresponding to Q235C steel plate is S235JR. S235JR is a non-alloy structural steel defined in the European Standard EN 10025-2:2004. Its chemical composition and mechanical properties are similar to Q235C, but specific values may differ. For example, S235JR typically has a carbon content below 0.22%, manganese content below 1.65%, and certain limits on phosphorus and sulfur content.

Comparing the Chinese and European standards, the main differences between Q235C and S235JR in chemical composition lie in manganese content and the restrictions on phosphorus and sulfur content. Additionally, the mechanical property requirements of both are similar, but there may be differences in certain details, such as specific values for yield strength and tensile strength, and how they vary with plate thickness.

In practical applications, if Q235C steel plate needs to be replaced with a European Standard material, S235JR can generally be used directly. However, attention should be paid to the slight differences in chemical composition and mechanical properties between the two, and selection should be made based on specific engineering requirements and standards. Additionally, considering that materials under different standard systems may have subtle process differences, it is advisable to consult relevant professionals or conduct necessary tests when substituting materials to ensure they meet engineering needs.