Characteristics of ASTM A533 Grade B Class3 Boiler Steel
High Strength and Toughness
Excellent Mechanical Properties:
Tensile Strength: 690-860 MPa (100-125 ksi)
Yield Strength: ≥750 MPa (83 ksi)
Elongation: ≥16% (for 2-inch/50mm specimens)
Superior Low-Temperature Toughness:
Suitable for low-temperature environments (-20°C to -60°C), commonly used in applications requiring resistance to brittle fracture, such as liquefied natural gas (LNG) storage equipment.
Alloying Element Strengthening
Chemical Composition:
Carbon (C): ≤0.25%
Manganese (Mn): 1.07-1.62%
Molybdenum (Mo): 0.41-0.64%
Nickel (Ni): 0.37-0.73%
Silicon (Si), Phosphorus (P), and Sulfur (S) are strictly controlled (P ≤ 0.035%, S ≤ 0.035%)
Function:
The combined addition of manganese, molybdenum, and nickel significantly enhances the steel's hardenability, temper resistance, and low-temperature toughness.
Heat Treatment Process
Quenching + Tempering:
Through quenching and high-temperature tempering (a form of thermal refinement), a tempered martensite structure is achieved, balancing strength and toughness to ensure material stability under high-pressure and high-temperature conditions.
Weldability and Machinability
Excellent Weldability:
Low carbon content (C ≤ 0.25%) reduces hardening tendencies in the heat-affected zone during welding, minimizing crack risks.
High Machinability:
Suitable for cutting, bending, forming, and other processes, meeting the manufacturing requirements for complex pressure vessel structures.
