The heat treatment process for Q355E I-beams is centered on normalizing, which improves the low-temperature toughness and strength uniformity of the material by refining the grain size and eliminating structural defects. This is combined with controlled rolling and controlled cooling (TMCP) processes to optimize performance. The following is a detailed analysis: First, the core heat treatment process for Q355E I-beams: The principle of normalizing treatment for Q355E I-beams: Heating the steel plate to 30-50℃ above Ac3 (typically around 870℃), holding at that temperature, and then air cooling. This process can: Eliminate hot-rolling defects, such as banded structures, improving anisotropy caused by coarse grains; Refine grains: reducing grain size through phase transformation recrystallization, improving impact toughness; Use uniform microstructure: making material properties more consistent in the thickness direction, reducing yield strength fluctuations. Performance Improvement Effects of Q355E I-beams Low-Temperature Toughness: Impact energy ≥34J at -40℃ with minimal fluctuation, suitable for projects in extremely cold regions; Strength Stability: Reduced yield strength dispersion after normalizing, avoiding performance differences within the same batch of materials; Weldability: Refined grains reduce the risk of embrittlement in the weld heat-affected zone, making them suitable for complex weld designs. Secondly, the Synergistic Effect of Controlled Rolling and Cooling (TMCP) Process for Q355E I-beams Process Principle of Q355E I-beams Controlling the final rolling temperature during rolling allows the steel plate to achieve a normalized microstructure through air cooling after rolling. This is achieved through: Dynamic Controlled Rolling: Adjusting rolling speed and deformation promotes grain refinement; Accelerated Cooling: Controlling the cooling rate prevents the formation of coarse grains. Comparison of Controlled Rolling and Cooling with Normalizing Treatment for Q355E I-beams Normalizing treatment is more expensive (requires additional heating) and produces finer, more uniform grains within the microstructure. Generally suitable for thick plates (≥30mm) and critical load-bearing structures. The TMCP process has a lower cost (rolling integration) and finer grain structure. Generally suitable for thin plates and mass production scenarios. Third, application scenarios of Q355E I-beam heat treatment: Q355E I-beams are used in critical load-bearing structures: Long-span bridge joints: Normalizing treatment can eliminate core defects in thick plates and improve fatigue resistance. Core supports of high-rise steel structures: TMCP process achieves efficient production through controlled rolling and cooling while meeting strength requirements. Q355E I-beams are used in low-temperature and dynamic load environments: Wind turbine towers (low-temperature areas): Normalized Q355E I-beams maintain high toughness at -40℃; Port crane machinery: Materials produced by the TMCP process have strong resistance to alternating loads and extend service life. Thick plate requirements for Q355E I-beams: Components with a thickness ≥30mm: Normalizing treatment can improve core properties and avoid the risk of lamellar tearing. Fourth, Recommendations for Process Selection of Q355E I-beams: Prioritize Normalizing Treatment: Suitable for applications requiring high low-temperature toughness and strength stability (e.g., buildings and bridges in northern regions); Suppliers must provide normalizing treatment records (furnace temperature profile, holding time) to ensure process traceability. Consider TMCP Process: Suitable for mass production and cost-sensitive projects (e.g., general industrial plants); Transverse properties of the material must be verified (especially when thickness ≥ 25mm) to avoid anisotropy issues.
Post time: Mar-20-2026