ASTM A847 — Yield Strength, Tensile Strength and Applications
Weathering cold-formed Hollow Structural Section (HSS). Forms a patina like A588 for exposed HSS that should serve unpainted. One grade, Fy 50 ksi.
Strength
| Grade | Fy (ksi) | Fu (ksi) | Note |
|---|---|---|---|
| — | 50 | 70 | Round and shaped alike. |
Fy and Fu are specification minimums. Verify the grade on the Mill Test Report (MTR); dual-certified material is common.
Applicable members
HSS Round, HSS Square, HSS Rectangular
Applicable is not the same as stocked. Confirm availability with the supplier.
Common applications
Exposed architectural HSS, railings, canopies, and frames intended to weather unpainted.
Field notes
- Same patina limits as A588: needs wet/dry cycling; may be unsuitable for continuously wet, sheltered, or chloride/marine exposure. Evaluate exposure and detailing.
- Closed sections need vent and drain detailing; trapped interior moisture will not weather protectively.
- Not a stock item everywhere; confirm availability early.
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+).