ASTM A572 Gr 55 — Yield Strength, Tensile Strength and Applications
ASTM A572 Grade 55: Fy 55 ksi, Fu 70 ksi (specified minimums). Multi-grade High-Strength Low-Alloy (HSLA) steel for shapes, plates and bars. Grade 50 is the workhorse for HP piles and higher-strength plate. Grades 60 and 65 are limited to lighter shapes and thinner plate.
Strength
| Grade | Fy (ksi) | Fu (ksi) | Note |
|---|---|---|---|
| 55 | 55 | 70 | To 2 in. thick. |
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, HP, C, MC, L, WT, MT, ST, plates, bars
American Institute of Steel Construction (AISC) preferred for: HP.
Applicable is not the same as stocked. Confirm availability with the supplier.
Common applications
HP bearing piles, high-strength plate girders, gusset and connection plates, transmission structures.
Field notes
- Grades 60 and 65: lighter shape groups and thinner plate only; check availability before design.
- Grade 50 is the AISC preferred spec for HP shapes.
- Commonly dual-certified A572-50 / A992 for W-shapes.
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+).