ASTM A913 Gr 70 — Yield Strength, Tensile Strength and Applications
ASTM A913 Grade 70: Fy 70 ksi, Fu 90 ksi (specified minimums). Quenched and Self-Tempered (QST) W-shapes with a low carbon equivalent, which may reduce preheat when permitted by the qualified welding procedure and code. Grades 50 through 80. Common for high-rise columns and heavy trusses.
Strength
| Grade | Fy (ksi) | Fu (ksi) | Note |
|---|---|---|---|
| 70 | 70 | 90 | High-rise columns. |
Fy and Fu are specification minimums. Verify the grade on the Mill Test Report (MTR); dual-certified material is common.
Applicable members
W shapes (all groups incl. heavy/jumbo), WT cut from W
Applicable is not the same as stocked. Confirm availability with the supplier.
Common applications
High-rise and heavy building columns, jumbo sections, long-span trusses.
Field notes
- Best value in heavy and jumbo columns where the low carbon equivalent may reduce preheat under the qualified welding procedure.
- Grade 50 has a capped-Fy seismic supplement (S75); call it out when required.
- Grades 65 through 80 shrink column sizes in tall buildings; confirm mill 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+).