Characteristics of ASTM A131 AH40 Steel
High Strength and Excellent Toughness
Yield Strength: ≥390 MPa; Tensile Strength: 510–640 MPa, capable of withstanding high-stress environments.
Low-Temperature Toughness: Impact energy ≥34 J at -20°C; ductile-to-brittle transition temperature ≤-50°C, suitable for cold marine or polar regions.
High Elongation: ≥20% (gauge length 50 mm), ensuring deformation capacity under load and preventing brittle fracture.
Superior Weldability
Low Carbon (C ≤0.18%) and Microalloyed Design (Nb+V+Ti ≤0.12%): Reduces welding crack risk.
Supports multiple welding methods, including submerged arc welding and CO₂ gas shielded arc welding, with a heat input of 15–28 kJ/cm, interpass temperature ≤180°C, and post-weld hydrogen relief treatment (200–250°C × 1 h).
Excellent Corrosion Resistance
Alloying with Corrosion-Resistant Elements: Cu (≤0.35%), Ni (≤0.40%), achieving ≥1,500 h without red rust in salt spray tests and a seawater immersion corrosion rate ≤0.08 mm/year.
Strict Purity Control: P ≤0.025%, S ≤0.015%, minimizing impurity effects on corrosion resistance.
Fatigue and Lamellar Tearing Resistance
Through-Thickness Reduction of Area: ≥35% (Z15 grade), resisting multidirectional stress tearing.
Nanoscale Precipitates [(Nb,V)(C,N)]: Refine grain structure, enhancing fatigue resistance for structures subjected to long-term alternating stress.
