In 2025, Huaxi Special Steel achieved a complete success in the R&D of Q355ND medium and heavy plate products, with its output reaching 10,453 tons in Q4. The specifications cover 12-50×2000-2500 mm. All performance indicators meet the requirements of the GB/T 1591-2018 standard, with some key parameters surpassing those of similar international products, marking a significant breakthrough achieved by Huaxi Special Steel in the field of low-alloy high-strength steel.

As a low-alloy high-strength structural steel, Q355ND features a low carbon equivalent, with the standard requiring a CEV of ≤ 0.43%. Utilizing the core technology of "medium carbon + multi-element microalloying" at the design stage, the product achieves a perfect balance between strength and toughness through accurate proportioning of microalloying elements such as niobium and titanium. For the challenging thin-gauge products, the rolling start temperature is defined by gauge category, and the controlled rolling and controlled cooling processes are precisely matched. To overcome technical difficulties, the Technology Center established a collaborative working group integrating sales, research and production, and underwent several minor adjustments to the composition and optimizations of the rolling process. Ultimately, the product achieved a yield strength of ≥ 365 MPa, a tensile strength of 480-600 MPa, and a low-temperature impact energy of ≥ 40 J at -20°C. Compared with the ordinary Q355D steel grade, its impact toughness is increased by 20%, the hardness of the weld heat-affected zone is reduced by 15%, and it can adapt to the wide temperature range working conditions from -40℃ to 500℃. During production, the enterprise adopts the LF refining process, with the N content controlled at ≤50 ppm, so as to ensure the stability of the product in extreme environments.

The development and mass production of Q355ND products will effectively meet the needs for horizontal comparative development of similar low-alloy products. And this will vigorously advance the upgrading of Huaxi Special Steel's steel product variety and structure.

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