ASTM A529 Gr 55 — Yield Strength, Tensile Strength and Applications
ASTM A529 Grade 55: Fy 55 ksi min, Fu 70–100 ksi (range). Higher-strength carbon-manganese steel for lighter shapes, plate, and bar. Offers 50 or 55 ksi yield in sections where A36 would otherwise govern. Limited to lighter shape groups and thinner material.
Strength
| Grade | Fy (ksi) | Fu (ksi) | Note |
|---|---|---|---|
| 55 | 55 | 70–100 | Plates and bars ≤ 1 in.; shapes with flange ≤ 1.5 in. |
Fy and Fu are specification minimums. Verify the grade on the Mill Test Report (MTR); dual-certified material is common.
Applicable members
M, S, HP, C, MC, L, lighter W, plates, bars
Applicable is not the same as stocked. Confirm availability with the supplier.
Common applications
Light framing and connection material where higher strength than A36 helps in thin sections.
Field notes
- Thickness and shape-group limits are the constraint; not for heavy sections.
- Fu range is wide (65–100); confirm on the MTR if Fu controls a connection check.
- For most 50 ksi needs, A572 Grade 50 is easier to source.
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+).