How to choose the suitable steel plate?

Basic principles: that is to ensure the safety and reliability of the steel plate, but also to use materials economically and reasonably.
Factors to consider when selecting steel plate:
1) The importance of structure;
2) The nature of the load;
3) Connection method;
4) The working temperature of the structure;

Steel plate for steel structure: Q235, Q345, Q390, Q420 should be used for load-bearing structure. Quality assurance: load-bearing structural steels should have tensile strength, elongation, yield strength (commonly referred to as three guarantees) and qualified guarantees for sulfur and phosphorus content.
Welded structural steel, in addition to satisfying the above items, should also have carbon content qualification guarantee, cold bending, impact toughness and other requirements.