ASTM A203 Grade D and E are both nickel alloy steels for pressure vessels, differing mainly in their nickel content, which impacts mechanical properties, especially low-temperature toughness; Grade D typically has 2.25% Ni, while Grade E is often considered a 3.5% Nickel (3.5-Ni) steel, offering better toughness for very cold service, though specifications can vary slightly by manufacturer and revision, with nickel acting as a strong ferrite strengthener.
ASTM A203 Grade D Chemical Composition and Mechanical Property
|
Grade |
Chemical Composition(%) |
||||
|
C |
Mn≥ |
Si |
P |
S |
|
|
A203 Grade D (A203GRD) |
0.17 |
0.7-0.8 |
0.13-0.45 |
0.035 |
0.035 |
|
Grade |
Mechanical Property |
|
|||
|
Tensile Strength(MPa) |
Yield Strength(MPa) |
% Elongation in 2 in.(50mm) min |
Impacting Test Temperature(°C) |
|
|
|
A203 Grade D (A203GRD) |
450 |
255 |
19 |
-20,40,-60 |
|
ASTM A203 Grade E Chemical Composition and Mechanical Property
|
Grade |
Chemical Composition(%) |
||||
|
C |
Mn≥ |
Si |
P |
S |
|
|
A203 Grade E (A203GRE) |
0.17 |
0.7-0.8 |
0.13-0.45 |
0.035 |
0.035 |
|
Grade |
Mechanical Property |
|
|||
|
Tensile Strength(MPa) |
Yield Strength(MPa) |
% Elongation in 2 in.(50mm) min |
Impacting Test Temperature(°C) |
|
|
|
A203 Grade E (A203GRE) |
485 |
275 |
21 |
-20,40,-60 |
|
Key Differences Summarized:
Nickel Content: Grade D usually around 2.25% Ni; Grade E generally higher, around 3.5% Ni.
Applications: Both for boilers/pressure vessels, but Grade E's higher nickel provides superior low-temperature ductility and impact resistance.
Properties: Nickel increases strength and toughness, especially in cold environments, making Grade E ideal for cryogenic or very cold service.
In More Detail:
ASTM A203 Standard: This standard covers nickel-alloy steel plates for pressure vessels, where nickel content dictates the grade.
Grade D: Often called 2.25% Ni steel, it's a workhorse for general pressure vessel applications needing good strength and weldability.
Grade E: Also known as 3.5% Ni steel, it's specifically designed for applications needing excellent performance at sub-zero temperatures, enhancing toughness.
When to Choose Which:
Choose Grade D for standard pressure vessels where moderate low-temperature performance is sufficient.
Choose Grade E when the service conditions involve significantly low temperatures, requiring enhanced ductility and impact toughness, making it excellent for liquefied gas or cryogenic storage.
