ASTM A533 Grade B and Grade D are low-alloy, pressure vessel quality (PVQ) steels, primarily differentiated by their alloying elements (especially Nickel for B vs. Molybdenum for D) and mechanical properties, with Grade D generally offering higher strength (often requiring Quenching & Tempering) and specified for demanding nuclear or high-temperature applications, while Grade B is a common choice for general pressure vessels but also used in nuclear sectors with specific class variations. Both grades come in classes (e.g., Class 1, 2, 3) that further define their heat treatment and strength levels.
Chemical composition Of ASTM A533 Grade B
|
Grade |
C % |
Mn %(<40mm) |
P% |
S% |
Si% |
Mo% |
Ni% |
|
A533 TYPE B |
0.25 |
1.07-1.82 |
0.035 |
0.035 |
0.13-0.45 |
0.41-0.84 |
0.37-0.73 |
Chemical composition Of ASTM A533 Grade C
|
Grade |
C % |
Mn %(<40mm) |
P% |
S% |
Si% |
Mo% |
Ni% |
|
A533 TYPE C |
0.25 |
1.07-1.82 |
0.035 |
0.035 |
0.13-0.45 |
0.41-0.84 |
0.67-1.03 |
Mechanical Property Of ASTM A533 Grade B
|
Grade |
Min Yield |
Tensile |
Thicknesss |
Elongation |
|
A533 TYPE C |
345 Mpa |
550-690Mpa |
<50MM |
18% |
Mechanical Property Of ASTM A533 Grade C
|
Grade |
Min Yield |
Tensile |
Thicknesss |
Elongation |
|
A533 TYPE B |
485 Mpa |
620-795Mpa |
<50MM |
16% |
ASTM A533 Grade B
Type: Carbon-manganese-nickel alloy steel.
Key Alloying: Contains Nickel (Ni) for improved toughness.
Common Classes: Class 1 (normalized) and Class 2 (quenched & tempered) are common, with Class 2 having higher strength.
Use: Widely used in boilers and pressure vessels, including nuclear reactor components.
ASTM A533 Grade D
Type: Manganese-molybdenum (Mn-Mo) alloy steel.
Key Alloying: Contains Molybdenum (Mo) for strength.
Common Classes: Class 3 is a notable variant, often requiring quenching and tempering for enhanced properties.
Use: Suited for high-strength applications, often in conjunction with Molybdenum for strength and creep resistance.
Key Differences Summarized
Alloying: Grade B adds Nickel; Grade D adds Molybdenum, changing its metallurgical response.
Strength: Grade D, particularly Class 3, typically offers higher minimum yield and tensile strengths, often achieved through quenching and tempering.
Application: Grade B is common, but Grade D (with its specific alloying) targets higher performance, especially where Molybdenum's properties are beneficial for high-temperature or specific service conditions.
