ASTM A242 / 242M
This specification covers high-strength low-alloy structural steel shapes, plates, and bars for welded, riveted, or bolted construction intended primarily for use as structural members where savings in weight [mass] or added durability are important. The atmospheric corrosion resistance of the steel in most environments is substantially better than that of carbon structural steels with or without copper addition. When properly exposed to the atmosphere, this steel can be used bare (unpainted) for many applications (see Note 1). This specification is limited to material up to 4 in. [100 mm], inclusive, in thickness.
Chemical Properties
| Element |
Composition, % |
Carbon, max
|
0.15 |
Manganese, max
|
1.00 |
Phosphorus, max
|
0.15 |
Sulfur, max
|
0.05 |
| Copper, min |
0.20 |
Mechanical Properties
| Elements |
Tensile strength, min, ksi [MPa] |
Yield point, min, ksi [MPa] |
Elongation in 8 in. [200 mm], min, % |
Elongation in 2 in. [50 mm], min, % |
| Plates and BarsA |
For thicknesses
3⁄4 in.[20 mm],
andunder |
70 [480] |
50 [345] |
18B,C |
21C |
| For thicknesses
over3⁄4 to 11⁄2 in.
[20 to 40
mm], incl |
67 [460] |
46 [315] |
18B,C |
21C |
| For thicknesses
over11⁄2 to 4 in.
[40 to 100
mm], incl |
63 [435] |
42 [290] |
18B,C |
21C |
| Structural Shapes |
For flange or
leg thicknesses
1.5 in. [40 mm]
and under |
70 [485] |
50 [345] |
18C |
21 |
| For flange
thicknesses
over 1.5 in.
[40 mm] to
2 in. [50
mm], incl |
67 [460] |
46 [315] |
18 |
21 |
| For flange
thicknesses
over 2 in.
[50 mm] |
63 [435] |
42 [290] |
18 |
21D |
Note :
A See the Orientation subsection in the Tension Tests section of Specification A6/A6M.
B Elongation not required to be determined for floor plate.
C For plates wider than 24 in. [600 mm] the elongation requirement is reduced two percentage points. See the Elongation Requirement Adjustments subsection in the Tension Tests section of Specification A6/A6M.
D For wide flange shapes over 426 lb/ft [634 kg/m], elongation in 2 in. [50 mm] of 18 % minimum applies.