ASTM A302 Grade B and Grade C are manganese-molybdenum alloy steels for pressure vessels, differing mainly in nickel content and impact toughness; Grade C adds Nickel (Ni) for better low-temperature performance and slightly higher elongation, while Grade B lacks Ni but shares similar tensile/yield strength, both used in boilers and petrochemical equipment.
Chemical Composition of A302 Grade B steel plate
|
Steel Grade |
The Element Max (%) |
||||||
|
C |
Si |
Mn |
P |
S |
Mo |
Ni |
|
|
A302 Grade B |
0.20-0.25 |
0.13-0.45 |
1.07-1.62 |
0.035 |
0.035 |
0.41-0.64 |
/ |
Chemical Composition of A302 Grade C steel plate
|
ASTM A302 Grade C Chemical Composition |
|||||||
|
Grade |
The Element Max (%) |
||||||
|
C |
Si |
Mn |
P |
S |
Al |
N |
|
|
A302 Grade C |
0.20-0.25 |
0.13–0.45 |
1.07-1.62 |
0,035 |
0,035 |
|
|
|
Nb |
V |
Ti |
Cu |
Cr |
Ni |
Mo |
|
|
|
|
|
|
|
0.37-0.73 |
0.41–0.64 |
|
Mechanical Property of A302 Grade B steel plate
|
Mechanical Property of A302 Grade B steel plate |
A302 Grade B |
|
Tensile strength, kis [MPa] |
80-100 [550-690] |
|
Yield strength, min, kis [MPa] |
50 [345] |
|
Elongation in 8 in. [200 mm], min, % |
15 |
|
Elongation in 2 in. [50 mm], min, % |
18 |
Mechanical Property of A302 Grade C steel plate
|
Grade |
|
ASTM A302 Grade C Mechanical Property |
||
|
Thickness |
Yield |
Tensile |
Elongation |
|
|
A302 Grade C |
mm |
Min Mpa |
Mpa |
Min % |
|
6-50 |
345 |
550-690 |
20% |
|
|
50-200 |
345 |
550-690 |
17% |
|
ASTM A302 Grade B
Composition: Manganese-Molybdenum (Mn-Mo) alloy steel.
Properties: Good strength, often supplied as-rolled, used in reactors, heat exchangers, and tanks.
Mechanicals (Typical): Tensile strength 550-690 MPa, Yield strength 345 MPa, Elongation ~18-20%.
ASTM A302 Grade C
Composition: Manganese-Molybdenum-Nickel (Mn-Mo-Ni) alloy steel, with added Nickel.
Properties: Higher toughness, especially at low temperatures, due to Nickel; slightly better elongation than Grade B.
Mechanicals (Typical): Tensile strength 550-690 MPa, Yield strength 345 MPa, Elongation ~20%.
Key Differences
Nickel: Grade C contains Nickel; Grade B does not.
Toughness: Grade C offers superior low-temperature impact toughness.
Elongation: Grade C generally has a higher minimum elongation percentage.
