ASTM A242 — Yield Strength, Tensile Strength and Applications
The original weathering High-Strength Low-Alloy (HSLA) steel. Largely superseded by A588 but still referenced and occasionally supplied. Yield drops with thickness.
Strength
| Grade | Fy (ksi) | Fu (ksi) | Note |
|---|---|---|---|
| — (≤ 0.75 in.) | 50 | 70 | — |
| — (0.75–1.5 in.) | 46 | 67 | — |
| — (1.5–4 in.) | 42 | 63 | — |
Fy and Fu are specification minimums. Verify the grade on the Mill Test Report (MTR); dual-certified material is common.
Applicable members
W, M, S, C, MC, L, plates, bars
Applicable is not the same as stocked. Confirm availability with the supplier.
Common applications
Older weathering-steel structures; occasional current use where specified.
Field notes
- Specify A588 for new work unless matching existing A242.
- Yield reduces with thickness; check the governing plate or flange thickness.
- Same patina exposure limits as any weathering steel.
Material constants
- Modulus of elasticity E: 29,000 ksi
- Shear modulus G: 11,200 ksi
- Density: 490 lb/ft³ (0.284 lb/in³)
- Poisson's ratio: 0.30
- Thermal expansion: 6.5 × 10⁻⁶ in/in/°F
These are the same for every structural steel grade. Strength changes with the specification; stiffness does not.
Related
- ASTM Structural Steel Grades Reference
chemistry, tolerances and the full specification behind this grade
- Steel Shape Properties Table
the sections this grade is supplied in
- Bolt Tensile & Shear Capacity Calculator
fastener grades to match this base metal
- Fillet Weld Strength Calculator
electrode selection to match this base metal
The full specification
Chemistry, tolerances, coatings, galvanizing, weldability, availability and substitutions for every spec: ASTM 101 (STL+).