ASTM A203 Grade A and B are nickel alloy steels for pressure vessels, differing mainly in nickel content, which impacts properties: Grade B has higher nickel (around 2.25%) for better low-temp toughness, making it common for boilers/oil/gas, while Grade A has less nickel, offering lower strength and ductility, suited for less demanding applications, though both aim for weldability and impact strength in different ranges.
Supplementary Technology: HIC Test | NACE MR0175 | Z15 | Z25 | Z35 | S1 | S2 | S3 | S4.1
S5 | S6 | S7 | S8 | S9| S11 | S12 | S14 | S17
Thickness: 6MM to 300MM,
Width: 1500mm to 4050mm,
Length: 3000mm to 15000mm
ASTM A202 Grade B
| Grade | Chemical Composition(%) | ||||
| C | Mn≥ | Si | P | S | |
| A202 Grade B (A202GRB) | 0.25 | 0.97-1.52 | 0.54-0.96 | 0.035 | 0.035 |
| Grade | Mechanical Property | ||||
| Tensile Strength(MPa) | Yield Strength(MPa) | % Elongation in 2 in.(50mm) min | Impacting Test Temperature(°C) | ||
| A202 Grade B (A202GRB)> | 585-760 | 325 | 18 | -20,40,-60 | |
ASTM A202 Grade A
| Grade | Chemical Composition(%) | ||||
| C | Mn≥ | Si | P | S | |
| A202 Grade A (A202GRA) | 0.17 | 0.97-1.52 | 0.54-0.96 | 0.035 | 0.035 |
| Grade | Mechanical Property | ||||
| Tensile Strength(MPa) | Yield Strength(MPa) | % Elongation in 2 in.(50mm) min | Impacting Test Temperature(°C) | ||
| A202 Grade A (A202GRA)> | 515-655 | 310 | 19 | -20,40,-60 | |
Key Differences
Nickel Content: This is the primary differentiator.
A203 Grade B: Contains about 2.25% Nickel.
A203 Grade A: Has a lower nickel content (typically around 0.40-0.70% or 0.40-1.00%, depending on exact standard version, but less than B).
Mechanical Properties (Impact Toughness):
Grade B: The added nickel significantly improves low-temperature impact toughness, making it superior for cryogenic or cold-service pressure vessels.
Grade A: Offers good ductility and weldability but less enhanced low-temperature performance than Grade B.
Applications:
Grade B: Widely used in high-pressure vessels, boilers, and oil/gas equipment where temperature fluctuations or low-temperature service is expected.
Grade A: Used in less severe service conditions where lower strength and ductility are acceptable.
