ASTM A285 Grades A and C are carbon steel plates for welded pressure vessels, differing primarily in strength and carbon content, with Grade C being stronger (higher tensile/yield) but less ductile (lower elongation) than Grade A, which offers better formability for lower-pressure uses, while Grade C suits higher pressure/temperature needs.
Chemical Composition of ASTM A285 Grade A
|
Element |
Composition (%) |
|---|---|
|
Carbon (C) |
0.17 max |
|
Manganese (Mn) |
0.90 max |
|
Phosphorus (P) |
0.035 max |
|
Sulfur (S) |
0.035 max |
Chemical Composition of ASTM A285 Grade c
|
Grade |
Chemical Composition(%) |
||||
|
C max |
Mn max |
Si |
P max |
Smax |
|
|
A285 Grade C
|
0.28 |
0.98 |
- |
0.035 |
0.03 |
Mechanical Properties of ASTM A285 Grade A
|
Property |
Value |
|---|---|
|
Tensile Strength |
45-65 ksi (310-450 MPa) |
|
Yield Strength |
24 ksi (165 MPa) min |
|
Elongation (in 200mm) |
27% min |
|
Elongation (in 50mm) |
30% min |
Mechanical Properties of ASTM A285 Grade C
|
Grade |
Mechanical Property |
|
|||
|
Tensile Strength(MPa) |
Yield Strength(MPa) |
% Elongation in 2 in.(50mm) min |
Impacting Test Temperature(°C) |
|
|
|
A285 Grade C
|
380-515 |
205 |
25 |
-20,40,-60 |
|
Key differences: Grade C has higher minimum yield (205 MPa vs. 165 MPa) and tensile (380-515 MPa vs. 310-450 MPa) strength, and lower elongation (23-27% vs. 27-30%), with Grade C also having a higher carbon limit (0.28% max vs. 0.17% max).
ASTM A285 Grade A
Strength: Lower strength (Tensile: 45-65 ksi / 310-450 MPa; Yield: min 24 ksi / 165 MPa).
Ductility: Higher elongation (min 27% in 8").
Carbon: Lower carbon content (max 0.17%), promoting better formability and weldability for less demanding applications.
Best For: Lower-pressure, simpler applications where formability is key, like some storage tanks.
ASTM A285 Grade C
Strength: Higher strength (Tensile: 55-75 ksi / 380-515 MPa; Yield: min 30 ksi / 205 MPa).
Ductility: Lower elongation (min 23% in 8").
Carbon: Higher carbon content (max 0.28%), contributing to its increased strength.
Best For: Higher pressure and temperature applications, making it the most common choice for boilers and heat exchangers.
