Effect of thermo-mechanical control process parameters on microstructure and mechanical properties of S460 steel for offshore wind power

To address the demand for high strength and toughness of S460 steel in complex marine environments, the effects of non-recrystallization zone rolling temperature, pass reduction rate, and holding thickness on microstructure and mechanical properties were investigated through ultra-purified smelting combined with thermo-mechanical controlled processing. The results indicated that reducing the rolling temperature in the non-recrystallization zone to 812℃ was found to promote grain refinement and dislocation strengthening, with the yield strength being elevated to 610.47MPa. At the same time, more quasi-polygonal ferrite was formed, improving both plasticity and toughness. When the pass reduction rate was raised to 26.0%, the amount of bainite and nano-sized particle precipitation increased, but the impact energy at -80℃ dropped to 142J, The optimal balance between strength and low-temperature toughness was achieved at a holding thickness of 40mm. This study demonstrates that the strengthtoughness synergy in S460 steel can be controlled by tailoring grain refinement, dislocation density, and precipitate distribution via TMCP, providing a robust process design basis for efficient manufacturing of offshore wind power structural steels.