1. Performance characteristics, uses and applicable scenarios
SA302GrB is a low-alloy high-strength manganese-molybdenum-nickel alloy steel plate that belongs to the ASTM A302 standard and is designed for high-temperature and high-pressure equipment such as pressure vessels and boilers. Its core performance characteristics include:
Excellent mechanical properties: tensile strength ≥550 MPa, yield strength ≥345 MPa, elongation ≥18%, and impact toughness meets the ASTM A20 standard.
Good welding performance: supports manual arc welding, submerged arc welding, gas shielded welding and other processes, and preheating and heat treatment are required after welding to prevent cracks.
High temperature resistance and corrosion resistance: Remains stable within the operating temperature range of -20℃ to 450℃, suitable for corrosive media environments such as acids and alkalis.
Lightweight and high strength: Through low alloying design, while reducing the weight of the structure, the pressure bearing capacity is improved and the equipment manufacturing cost is reduced.
Applicable scenarios: key equipment in the fields of petrochemicals, power plant boilers, nuclear power plants, hydropower generation, etc., such as reactors, heat exchangers, spherical tanks, nuclear reactor pressure vessels, boiler drums, etc.
2. Main components, performance parameters and mechanical properties
Chemical composition (melting analysis):
C (carbon): ≤0.25% (≤0.20% when thickness ≤25mm)
Mn (manganese): 1.07%-1.62% (1.15%-1.50% when thickness ≤25mm)
P (phosphorus): ≤0.035% (some standards require ≤0.025%)
S (sulfur): ≤0.035% (some standards require ≤0.025%)
Si (silicon): 0.13%-0.45%
Mo (molybdenum): 0.41%-0.64% (some standards require 0.45%-0.60%)
Ni (nickel): 0.40%-0.70% (some thickness range)
Performance parameters:
Tensile strength: 550-690 MPa (80-100 ksi)
Yield strength: ≥345 MPa (50 ksi)
Elongation: ≥15% when gauge length is 200mm, ≥18% when gauge length is 50mm
Heat treatment state: Delivery in normalizing, normalizing + tempering or controlled rolling state, normalizing treatment is required when thickness >50mm.
Mechanical performance advantages:
Balance of high strength and toughness: At 550-690 MPa tensile strength, it still maintains an elongation of ≥18%, ensuring the equipment’s ability to resist brittle fracture.
Fine grain structure: Meets the fine grain size requirements of the A20/A20M standard and improves low-temperature impact toughness.
3. Application cases and advantages
Petrochemical industry:
Application case: A petrochemical enterprise uses SA302GrB steel plates to manufacture high-pressure reactors, which have been running continuously for 5 years at 400℃ and 30 MPa without cracks or deformation.
Advantages: Excellent resistance to hydrogen corrosion, and 100% ultrasonic flaw detection of welds ensures equipment safety.
Nuclear power plant field:
Application case: The reactor pressure vessel of a nuclear power plant adopts SA302GrB steel plate with a thickness of 120mm. Through normalizing + tempering treatment, the radiation resistance is improved by 30%.
Advantage: Molybdenum content of 0.45%-0.60% inhibits neutron irradiation embrittlement and meets the requirements of ASME specifications.
Power station boiler field:
Application case: A supercritical boiler drum adopts SA302GrB steel plate, which operates at 540℃ and 25 MPa, and its service life is extended to 30 years.
Advantage: High temperature short-time strength reaches 690 MPa, which is 15% lighter than carbon steel and reduces energy consumption.
Hydropower generation field:
Application case: The high-pressure water pipe of a hydropower station adopts SA302GrB steel plate and passes 200,000 fatigue tests in an environment of -20℃ to 50℃.
Advantage: Low temperature impact toughness (≥27 J at -20℃) meets the extreme climate requirements of mountainous areas.
4. Safety, environmental protection and industrial importance
Safety:
Passed ASTM A20 impact test (V-notch impact energy ≥34 J at -20℃), ensuring the risk of low-temperature brittle fracture is less than 0.1%.
The hardness of the heat-affected zone of the weld is ≤350 HV to prevent hydrogen-induced cracking.
Environmental protection:
The molybdenum content of 0.41%-0.64% reduces the use of nickel and reduces heavy metal emissions.
Complies with the EU RoHS directive and prohibits the use of harmful substances such as lead and mercury.
Industrial importance:
It accounts for 25% of the global pressure vessel steel plate market and is a key material for the localization of nuclear power and petrochemical equipment.
Supports wide temperature range applications from -20℃ to 450℃, and improves equipment operating efficiency by 15%-20% compared with traditional carbon steel.
Conclusion
SA302GrB steel plate has become the core material of modern industrial high-temperature and high-pressure equipment due to its high strength, corrosion resistance and easy welding. Its balance of safety, environmental protection and cost-effectiveness makes it irreplaceable in the fields of nuclear power, petrochemicals, energy, etc., and it is driving the development of industrial equipment towards a more efficient and safer direction.
Post time: Jun-04-2025