An ultra-low sulfur fine-grain strengthened high fatigue microalloyed chain steel

Abstract

This invention relates to the field of structural steel for chains, specifically to an ultra-low sulfur, fine-grained, high-fatigue microalloyed chain steel. Its chemical composition, by mass fraction, is: C 0.46–0.55%, Si 0.17–0.35%, Mn 0.65–0.96%, P≤0.020%, S≤0.02%, Cr 0.10–0.25%, Ni≤0.02%, Cu≤0.02%, acid-soluble aluminum (Al) 0.02–0.05%, with the balance being Fe and unavoidable impurities. The beneficial effects are: this invention, through a technical solution of "ultra-low sulfur + acid-soluble aluminum fine grains + trace Cr synergistic strengthening," significantly improves the fatigue strength and toughness of the chain steel without adding expensive alloys or changing conventional processes. The resulting steel has a rotational bending fatigue strength (10⁷ cycles) ≥420MPa, excellent comprehensive mechanical properties, and minimal increase in production cost. It can be mass-produced and can completely replace existing conventional chain steel. It solves the technical pain points of poor fatigue performance or high cost of existing technologies and has outstanding industrialization value and import substitution advantages.