1. No Improvement to Intrinsic Corrosion Resistance
Cold rolling cannot enhance the inherent atmospheric corrosion resistance of SPA-H weathering steel plate. This core performance is determined by the steel's fixed Cu/Cr/P alloy composition and corrosion-resistant precipitate distribution, while cold rolling is only a room-temperature physical deformation process that does not alter the chemical composition or the patina-forming mechanism of the steel.
2. Minor Auxiliary Benefit to Practical Corrosion Performance
Cold rolling removes the rough mill scale and oxide layer on the hot-rolled SPA-H surface, creating a smooth, defect-free surface. This optimizes the uniformity of initial patina formation in the early stage of outdoor exposure, avoiding localized uneven oxidation caused by surface defects, and ensuring the protective patina grows consistently across the entire plate surface.
3. No Fundamental Change to Corrosion Rate or Patina Quality
Even with the smooth surface from cold rolling, the long-term atmospheric corrosion rate of cold-rolled SPA-H (0.01–0.03 mm/year) and the density, stability, and protective performance of the formed patina are completely consistent with hot-rolled SPA-H, with no substantive improvement to anti-corrosion effects.
4. No Elimination of Inherent Corrosion Limitations
Cold rolling cannot expand the applicable corrosive environment range of SPA-H. Cold-rolled SPA-H still has poor corrosion resistance in harsh marine/salt-spray, high-temperature humid, and acid/alkali corrosive environments, the same as hot-rolled SPA-H.
