Steel HSLA · supply condition · default condition
Steel HSLA-HR
Properties of the HR condition, compared with the other HSLA tempers.
Default stock condition for structural plate, sections and hot-rolled coil; best price per unit strength.
What is HSLA-HR?
HSLA-HR is HSLA supplied in the HR condition — default stock condition for structural plate, sections and hot-rolled coil; best price per unit strength. HSLA-HR has a yield strength of 345 MPa (50 ksi) and a tensile strength of 490 MPa (71.1 ksi) — weaker than 75% of steel grades. Elongation at break is 21% and the elastic modulus is 205 GPa (29.7 Msi). HSLA-HR has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,425°C (2,597 °F).
Advantages
- Readily welded — 80/100, better than 80% of steel grades
Limitations
- Low strength — 345 MPa (50 ksi), worse than 75% of steel grades
HSLA-HR properties
Typical room-temperature values for HSLA-HR — 11 properties are specific to this condition; the rest are grade-level values shared by every HSLA temper. Each bar shows where the value sits among the steel grades in FabDigit's library — further right is higher.
Physical3
HSLA-HR has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,425°C (2,597 °F).
Mechanical16
HSLA-HR has a yield strength of 345 MPa (50 ksi) and a tensile strength of 490 MPa (71.1 ksi) — weaker than 75% of steel grades. Elongation at break is 21% and the elastic modulus is 205 GPa (29.7 Msi).
Thermal6
HSLA-HR is rated for continuous service to 400°C (752 °F). It conducts heat at 45 W/m·K (26 BTU/hr·ft·°F), better than 66% of steel grades. Thermal expansion is 12 µm/m·K (6.67 µin/in·°F).
Electrical3
HSLA-HR conducts electricity at 9 % IACS, better than 70% of steel grades.
Chemical & Environmental3
Corrosion resistance is poor (16/100), better than 79% of steel grades.
Sustainability4
Producing a kilogram of HSLA-HR takes about 25 MJ of energy and emits 2 kg of CO₂ — less than 82% of steel grades. Typical recycled content is 30%.
Manufacturability8
HSLA-HR's machinability is good (58/100, better than 75% of steel grades); weldability very good (80/100); formability good (60/100).
Common Calculations5
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Other HSLA tempers and conditions
HSLA is also supplied in 5 other conditions. The full side-by-side table is on the HSLA overview.
- HRDefaultDefault stock condition for structural plate, sections and hot-rolled coil; best price per unit strength.345 MPa yield · 150 HB
- QTHighest-strength HSLA route for naval hull, crane boom and heavy equipment plate where 550–700 MPa yield with good toughness is required.620 MPa yield · 22 HRC
- TMCPUse for thick plate needing high strength plus low-temperature toughness and low carbon equivalent for field welding (ships, bridges, offshore).430 MPa yield · 175 HB
- CRChoose for thin-gauge stamped parts needing tight thickness tolerance, clean surface and higher yield than CQ steel.380 MPa yield · 160 HB
- NSpecify when uniform fine grain and guaranteed sub-zero Charpy values are needed in thicker plate or after hot forming.360 MPa yield · 155 HB
- GalvanizedPick when corrosion protection must survive forming and no post-paint is planned (auto body, HVAC, framing).350 MPa yield · 150 HB
Working with HSLA-HR
Is HSLA easy to machine?
Machines like a tough medium-carbon steel — use rigid setups, positive-rake carbide, moderate speeds and generous feed; micro-alloy carbonitrides cause slightly faster tool wear than plain 1020, and Q&T grades need reduced speed.
Can HSLA be welded?
Low carbon equivalent makes most HSLA prequalified for SMAW/GMAW/SAW with matching-strength consumables; keep heat input controlled (excess input coarsens the HAZ and erodes toughness) and preheat 50–150 °C for thick or Q&T plate.
Can HSLA be formed, bent or molded?
Cold forms well but needs larger bend radii, higher press tonnage and 2–3× the springback compensation of mild steel; roll or press-brake with sheared edges deburred to avoid edge cracking, and avoid re-forming Q&T grades.
What surface finishes work on HSLA?
No anodizing; specify blast + zinc-rich primer/paint, hot-dip galvanize (watch silicon/phosphorus for coating thickness), phosphate + e-coat, or use a weathering-type HSLA composition for bare patina service.
HSLA chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| C≤0.20 % typical for weldable micro-alloyed grades | ≤ 0.23 | 0.12 |
| Mn | 0.6 – 1.7 | 1.3 |
| Si | ≤ 0.55 | 0.3 |
| P | ≤ 0.04 | 0.02 |
| S≤0.010 % for Ca-treated / low-temp grades | ≤ 0.04 | 0.01 |
| Nbgrain refinement + precipitation strengthening | 0.01 – 0.11 | 0.03 |
| V | 0.01 – 0.15 | 0.05 |
| TiN fixing, grain size control | ≤ 0.15 | 0.02 |
| Alacid-soluble, deoxidation | 0.02 – 0.06 | 0.03 |
| Cuup to 1.2 % in Cu-precipitation HSLA-80/100 | ≤ 0.6 | 0.2 |
| Nihigher in Q&T naval grades | ≤ 0.9 | 0.1 |
| Cr | ≤ 0.7 | 0.1 |
| Mo | ≤ 0.3 | 0.02 |
| N | ≤ 0.01 | 0.01 |
| Fe | balance | — |
HSLA-HR — frequently asked
What is HSLA-HR used for?
HSLA-HR is typically used for bridge girders and plate sections, building and structural frames, crane and excavator booms, truck chassis frames and crossmembers, automotive body structural reinforcements and pressure vessel shells. In short: high-strength low-alloy plate.
What is the yield strength of HSLA-HR?
HSLA-HR has a typical yield strength of 345 MPa (50 ksi) and a tensile strength of 490 MPa (71.1 ksi) — weaker than 75% of steel grades. Strength varies by condition: see the 6 listed tempers.
Is HSLA-HR easy to machine?
Reasonably — machinability is rated good (58/100, better than 75% of steel grades). Machines like a tough medium-carbon steel — use rigid setups, positive-rake carbide, moderate speeds and generous feed; micro-alloy carbonitrides cause slightly faster tool wear than plain 1020, and Q&T grades need reduced speed.
Can HSLA-HR be welded?
Yes — weldability is rated very good (80/100). Low carbon equivalent makes most HSLA prequalified for SMAW/GMAW/SAW with matching-strength consumables; keep heat input controlled (excess input coarsens the HAZ and erodes toughness) and preheat 50–150 °C for thick or Q&T plate.
What surface finishes work on HSLA-HR?
No anodizing; specify blast + zinc-rich primer/paint, hot-dip galvanize (watch silicon/phosphorus for coating thickness), phosphate + e-coat, or use a weathering-type HSLA composition for bare patina service.
Can HSLA-HR be formed, bent or molded?
Cold forms well but needs larger bend radii, higher press tonnage and 2–3× the springback compensation of mild steel; roll or press-brake with sheared edges deburred to avoid edge cracking, and avoid re-forming Q&T grades.
What is the maximum service temperature of HSLA-HR?
HSLA-HR is rated for continuous use to about 400°C (752 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between HSLA-HR and HSLA-QT?
HR is the default condition — default stock condition for structural plate, sections and hot-rolled coil; best price per unit strength. QT: highest-strength HSLA route for naval hull, crane boom and heavy equipment plate where 550–700 MPa yield with good toughness is required. Yield strength is 345 MPa in HR versus 620 MPa in QT.
Can FabDigit make parts in HSLA-HR?
Yes — HSLA-HR is available for CNC machining and sheet metal with instant online pricing. Upload a STEP file to get a price and a DFM check.
Sources
- ASTM A572/A572M — High-Strength Low-Alloy Columbium-Vanadium Structural Steel — ASTM International (2021)
- ASTM A1008/A1011 — Cold/Hot-Rolled Steel Sheet, HSLAS — ASTM International (2021)
- ASTM A653/A653M — Zinc-Coated (Galvanized) Sheet, SS and HSLAS — ASTM International (2020)
- EN 10025-2/-4 Hot rolled structural steels (S355, S420M/ML) — CEN (2019)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
- ASM Handbook Vol.14A/14B — Metalworking: Forming and Sheet Metal — ASM International (2006)
- ASM Handbook Vol.19 — Fatigue and Fracture — ASM International (1996)
- HSLA structural plate datasheets (ArcelorMittal, Nucor, Baosteel) — various producers (2023)
Property data is compiled from published supplier and standards handbooks and normalised for comparison. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.