Q355 has replaced Q345

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Do you know that Q355 has replaced Q345? Q355 has taken the place of Q345 If you see the material specified as Q355B in the general design specifications of a steel structure or pressure vessel drawing, under no circumstances should you say that the designer made a mistake. In fact, designers keep up with the times, while you’re left behind! In accordance with the GB/T 1591-2018 standard for \"Low-alloy high-strength structural steel\", the Q345 grade was discontinued as of February 1, 2019, and Q355 was adopted as the new standard, corresponding to the EU’s S355 standard. Previously, in accordance with GB/T 1591-2008, Q345 was specified; however, this did not align with standards in the European Union. The new standard GB/T 1591-2018 now specifies Q355 instead. Both grades have the same tensile strength, elongation after fracture, and resistance to low temperatures, with the only difference being their yield strength. For more details, refer to the relevant standards. The key performance parameters of Q355 are as follows: 1. Yield strength: The yield strength of Q355 is 355 MPa, which is higher than that of Q345 (345 MPa). 2. Other properties: Indicators such as tensile strength, elongation, and tensile temperature are basically the same as those of Q345, with only the yield strength being slightly adjusted. II. The main performance comparisons of the two grades of steel are as follows: 1. Main properties of Q345: 2. Main properties of Q355: III. The areas where substitution is applicable include traditional applications of Q345 such as construction, bridges, and pressure vessels; new design projects must use Q355 material. For old project renovation projects, the Q345 grade specified in the historical drawings can be used, but re-testing of the materials is required to confirm equivalent actual performance.