A588 Grade A and A633 Grade A are ASTM high-strength low-alloy (HSLA) steels, but differ in application and properties: A588 Gr. A is a weathering steel for atmospheric corrosion resistance (like bridges), forming a protective rust layer, while A633 Gr. A is a normalized steel for general structural use, offering good notch toughness at low temperatures (down to -50℃F), with A588 Gr. A having higher strength (50 ksi yield) than A633 Gr. A (42 ksi yield) in thicker sections.
Chemical Composition of A588 Grade A
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ASTM A588 Chemical Composition |
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|
C |
P |
S |
|||||
|
A588 |
0.19 |
0.30-0.65 |
0.80-1.25 |
0.04 |
0.05 |
0.40 |
.. |
|
N |
V |
|
|
||||
|
0.25-0.40 |
0.40-0.65 |
… |
0.01 |
0.02-0.10 |
|
|
|
Chemical Composition of A633 Grade A
|
C |
|
|
P |
S |
|
N |
|
0.18 |
0.15-0.50 |
1.00-1.35 |
0.035 |
0.04 |
|
|
|
|
|
|
|
|
|
V |
|
|
|
|
0.05 |
|
|
|
Mechanical properties of A588 Grade A
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Mechanical Property of A588 Grade A steel plate |
A588 Grade A |
|
100mm or under |
[485] |
|
100mm-125mm |
[460] |
|
125mm-200mm |
[435] |
|
100mm or under |
[345] |
|
100mm-125mm |
[315] |
|
125mm-200mm |
[290] |
|
Elongation in under. [50 mm], min, % |
21 |
|
Elongation in under. [50 mm-200mm], min, % |
18 |
Mechanical properties of grade A633 Grade A
|
|
-35 |
-20 |
0 |
25 |
|
Notch impact test. Min. absorbed energy J |
41 |
54 |
61 |
68 |
|
|
to 65 |
65 - 100 |
100 - 150 |
|
ReH - Minimum yield strength (MPa) |
290 |
290 |
|
|
|
To 65 |
65- 100 |
100-150 |
|
Rm -Tensile strength (MPa) |
430-570 |
430-570 |
|
|
|
200 |
50 |
|
A - Minimum elongation Lo=5,65 √ So (%) Longitudinal |
18 |
23 |
Corrosion: A588 is specifically for corrosion resistance (weathering), A633 isn't inherently "weathering" but good for cold temps.
Strength: A588 generally offers higher strength than A633 for comparable thicknesses, especially in common ranges.
Processing: A633 is normalized, a heat treatment for refined grain structure, while A588 develops its protective patina over time.
