What Is HSLA Steel
High-Strength Low-Alloy (HSLA) steel provides improved mechanical properties and greater atmospheric corrosion resistance than carbon steels, with total alloy content typically below 2-3%. Unlike Q&T steels, HSLA derives strength from controlled chemistry and thermomechanical processing.
HSLA Steel Grades and Specifications
| Standard | Grade | Yield (MPa) | Tensile (MPa) | Typical Use |
|---|---|---|---|---|
| ASTM A572 | 42 | 290 | 415 | Bridges, buildings |
| ASTM A572 | 50 | 345 | 450 | Heavy structures, crane booms |
| ASTM A572 | 60 | 415 | 520 | Mining equipment |
| ASTM A572 | 65 | 450 | 550 | Weight-critical structures |
| ASTM A656 | 80 | 550 | 620 | Improved formability |
| ASTM A871 | 70 | 485 | 585 | Weathering applications |
Strengthening Mechanisms
- Grain Refinement (Hall-Petch): Fine austenite grain size (ASTM 10-12) through Nb, V, Ti microalloying
- Precipitation Strengthening: Fine NbC, VC, TiC precipitates add 50-150 MPa
- Solid Solution Strengthening: Mn, Si, Cu, Ni, Cr, Mo in ferrite matrix
- TMCP: Thermo-Mechanical Controlled Processing for optimal microstructure
Mechanical Properties
| Property | A572 Gr.50 | A572 Gr.65 | A871 Gr.70 |
|---|---|---|---|
| Yield Strength (min) | 345 MPa | 450 MPa | 485 MPa |
| Tensile Strength (min) | 450 MPa | 550 MPa | 585 MPa |
| Elongation (min) | 18% | 15% | 15% |
| Weldability (CE max) | 0.45 | 0.50 | 0.50 |
Welding Considerations
| Grade | Thickness (mm) | Min Preheat |
|---|---|---|
| A572 Gr.50 | 20 or less | None |
| A572 Gr.50 | 20-40 | 65C |
| A572 Gr.65 | Any | 100C |
Common Applications
- Building construction: High-rise structural frames (A572 Gr.50)
- Bridge construction: Main girders, deck plates (A572 Gr.50/60)
- Transportation: Truck frames, crane booms (A572 Gr.60/65)
- Offshore: Platform structures (A572 Gr.50 with impact)
- Architecture: Exposed structural elements (A871 weathering)
- Wind energy: Tower sections, monopiles (A572 Gr.50/60)
Sourcing HSLA Steel
CoreMetal Steel supplies HSLA steel plate, sheet, structural sections, and bar in all major ASTM grades (A572, A656, A871, A606) with full mill certification, impact testing to -40C available.
Get a Quote for Your Steel Project
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