Steel A588
ASTM A588 · UNS K11430
A588 is a high-strength low-alloy weathering structural steel in which Cu-Cr-Ni-P microalloying forms a dense, stable oxide patina on atmospheric exposure, reducing the corrosion rate of bare steel to 1/4–1/8 that of plain carbon steel.
Values for the HR condition
A588 tempers and conditions
A588 is supplied in 8 conditions, soft to hard. HR is the default FabDigit quotes; the values on this page are for it.
Compare all 8 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Heavy plate 125–200 mm | For plate over 100 mm thick, where A588 permits lower specified yield/tensile minima. | 330 | 490 | 24 | 145 HB | 8.6 % IACS |
Grade K | Lower-carbon option for improved weld and bend behaviour at equal 345 MPa yield. | 375 | 520 | 25 | 150 HB | 49 W/m·K |
HRDefault Hot rolled | Standard stocked condition for structural plate, beams and bar; bare-exposure weathering use. | 380 | 520 | 25 | 155 HB | 8.6 % IACS |
Cold rolled | Thin gauge sheet for cladding/panels where tight thickness tolerance and a smoother start surface are wanted. | 380 | 500 | 22 | 160 HB | 8.6 % IACS |
Grade A | Use where the classic higher-silicon weathering chemistry is specified; mechanicals identical to Grade B. | 380 | 530 | 24 | 155 HB | 48 W/m·K |
Grade C | Alternate licensed chemistry supplied by some mills; same strength class as Grades A/B. | 380 | 520 | 25 | 155 HB | 8.6 % IACS |
Normalized | Specified for thick plate or fracture-critical/low-temperature service needing guaranteed CVN energy. | 390 | 530 | 27 | 150 HB | 8.6 % IACS |
Grade B | Default mill chemistry for plate and shapes; best balance of weldability and weathering index. | 390 | 540 | 23 | 160 HB | 47 W/m·K |
Supply forms, finishes and certifications
Ways A588 is supplied — form, process route, surface or paperwork — without a datasheet of their own. The property values above apply.
| Option | What it is | Type |
|---|---|---|
Pre-weathered | Shot-blasted and accelerated-patinated (pre-rusted) surface | Surface finish |
Galvanized | Hot-dip zinc coated weathering steel | Coating |
What is A588?
A588 is a high-strength low-alloy weathering structural steel in which Cu-Cr-Ni-P microalloying forms a dense, stable oxide patina on atmospheric exposure, reducing the corrosion rate of bare steel to 1/4–1/8 that of plain carbon steel. It is normally supplied as hot-rolled plate and shapes with 345 MPa minimum yield and 485 MPa minimum tensile, welds much like other low-alloy steels, and is used bare for bridges, facades, sculpture and container structures. The patina only stabilises under alternating wet-dry cycles: in permanently damp, ponded, salt-spray or de-icing-salt service it will not passivate, and rust run-off stains adjacent surfaces. In those conditions use painted A572 Gr.50 instead. A588 has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,490°C (2,714 °F). A588 has a yield strength of 380 MPa (55.1 ksi) and a tensile strength of 520 MPa (75.4 ksi) — weaker than 68% of steel grades. Elongation at break is 25% and the elastic modulus is 200 GPa (29 Msi).
What is A588 used for?
- Weathering steel bridge girders
- Architectural facade and cladding panels
- Outdoor sculptures and monuments
- Shipping container structures
- Retaining walls and sound barriers
- Sign structures and light poles
- Railcar and hopper bodies
Advantages
- Conducts heat well — 52 W/m·K (30 BTU/hr·ft·°F), better than 98% of steel grades
- Good corrosion resistance — 32/100, better than 96% of steel grades
- Tough — resists crack growth — 120 MPa·√m (109.2 ksi·√in), better than 81% of steel grades
- Readily welded — 78/100, better than 78% of steel grades
- Ductile — tolerates forming and impact — 25%, better than 77% of steel grades
Limitations
- Hard to polish — 45/100, worse than 84% of steel grades
A588 properties
Typical room-temperature values for A588-HR; bars are the position among steel grades.
Physical3
A588 has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,490°C (2,714 °F).
Mechanical16
A588 has a yield strength of 380 MPa (55.1 ksi) and a tensile strength of 520 MPa (75.4 ksi) — weaker than 68% of steel grades. Elongation at break is 25% and the elastic modulus is 200 GPa (29 Msi).
Thermal6
A588 is rated for continuous service to 400°C (752 °F). It conducts heat at 52 W/m·K (30 BTU/hr·ft·°F), better than 98% of steel grades. Thermal expansion is 11.7 µm/m·K (6.5 µin/in·°F).
Electrical3
A588 conducts electricity at 8.6 % IACS, better than 66% of steel grades.
Chemical & Environmental3
Corrosion resistance is poor (32/100), better than 96% of steel grades.
Sustainability4
Producing a kilogram of A588 takes about 25 MJ of energy and emits 2 kg of CO₂ — less than 82% of steel grades. Typical recycled content is 30%.
Manufacturability7
A588's machinability is good (55/100, better than 62% of steel grades); weldability very good (78/100); 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.
Strength versus weight in the steel family
Yield strength against density for every steel grade FabDigit runs. A588 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with A588
Is A588 easy to machine?
Machines like a 345 MPa-class HSLA steel — roughly 55–60 % of AISI 1212; carbide tooling, moderate speeds, slightly gummy chips from the Cu addition.
Can A588 be welded?
Prequalified in AWS D1.1; use weathering-matched consumables (E80xx-W, ER80S-G, or three-pass rule with mild-steel filler) so the weld patinates with the base metal, and preheat thick sections per CE.
Can A588 be formed, bent or molded?
Cold bends and press-brake work readily at generous radii (≈2–3 t for plate); hot forming is fine but avoid slow cooling that coarsens grain, and re-normalize thick sections if toughness is critical.
Manufacturability
The process limits FabDigit applies to A588. Every A588 part is priced by an engineer; design inside these and the quote comes back without a redesign loop.
CNC machining
| Machinability | Good55 / 100 |
|---|---|
| ISO material group | P.2 |
| Cutting speed (rough / finish) | 180 / 210 m/min |
| Minimum wall | 0.8 mm |
| Minimum internal radius | 1 mm |
| Drill depth limit | 5× diameter |
| Best surface (machined / polished) | Ra 1.6 / — |
| Hardenable after machining | No |
Sheet metal
| Formability | Better60 / 100 |
|---|---|
| Weldability | Better78 / 100 |
A588 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 |
|---|---|---|
| CGrade B; Grade A 0.19 max, Grade K 0.17 max | ≤ 0.2 | 0.15 |
| MnGrade B | 0.75 – 1.35 | 1.05 |
| SiGrade A 0.30–0.65 | 0.15 – 0.5 | 0.3 |
| P | ≤ 0.04 | 0.02 |
| S0.030 max typical mill practice | ≤ 0.05 | 0.01 |
| Cr | 0.4 – 0.7 | 0.55 |
| Cukey weathering element | 0.2 – 0.4 | 0.3 |
| Ni | ≤ 0.5 | 0.25 |
| V | 0.01 – 0.1 | 0.05 |
| Fe | balance |
What surface finishes work on A588?
Grit-blast to bare metal and leave exposed to develop the patina (allow drainage, avoid crevices and rust run-off onto adjacent surfaces); alternatively paint, metallize or hot-dip galvanize — anodizing is not applicable.
Surface treatments FabDigit runs on steel parts — pick them in the quote configurator or call them out on the drawing. Each links to its datasheet in the surface-finish library (thickness, specs, call-out, material verdicts).
Plating
CVD Coating
Black / Phosphate
Thermal Spray
Equivalent designations
Standards and trade names that resolve to Steel A588 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- UNS
- K11430
- Trade names
- Corten ACorten B
- Also called
- Cor-Ten
- Similar grades
- S355J0WQ355GNH
How much does A588 cost?
A588 is a standard-cost steel ($$), cheaper than about 80% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
A588 — frequently asked
What is A588 used for?
A588 is typically used for weathering steel bridge girders, architectural facade and cladding panels, outdoor sculptures and monuments, shipping container structures, retaining walls and sound barriers and sign structures and light poles. In short: rust-resistant weathering steel.
What is the yield strength of A588?
A588 has a typical yield strength of 380 MPa (55.1 ksi) and a tensile strength of 520 MPa (75.4 ksi) — weaker than 68% of steel grades. Strength varies by condition: see the 8 listed tempers.
Is A588 easy to machine?
Reasonably — machinability is rated good (55/100, better than 62% of steel grades). Machines like a 345 MPa-class HSLA steel — roughly 55–60 % of AISI 1212; carbide tooling, moderate speeds, slightly gummy chips from the Cu addition.
Can A588 be welded?
Yes — weldability is rated very good (78/100). Prequalified in AWS D1.1; use weathering-matched consumables (E80xx-W, ER80S-G, or three-pass rule with mild-steel filler) so the weld patinates with the base metal, and preheat thick sections per CE.
What surface finishes work on A588?
Grit-blast to bare metal and leave exposed to develop the patina (allow drainage, avoid crevices and rust run-off onto adjacent surfaces); alternatively paint, metallize or hot-dip galvanize — anodizing is not applicable.
Can A588 be formed, bent or molded?
Cold bends and press-brake work readily at generous radii (≈2–3 t for plate); hot forming is fine but avoid slow cooling that coarsens grain, and re-normalize thick sections if toughness is critical.
What is the maximum service temperature of A588?
A588 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 A588-HR and A588-N?
HR is the default condition — standard stocked condition for structural plate, beams and bar; bare-exposure weathering use. N: specified for thick plate or fracture-critical/low-temperature service needing guaranteed CVN energy. Yield strength is 380 MPa in HR versus 390 MPa in N.
How much does A588 cost?
A588 is a standard-cost steel ($$), cheaper than about 80% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Can FabDigit make parts in A588?
Yes — A588 is available for CNC machining and sheet metal; every part is priced by an engineer rather than instantly. Upload a STEP file to get a price and a DFM check.
Sources
- ASTM A588/A588M — High-Strength Low-Alloy Structural Steel with Atmospheric Corrosion Resistance — ASTM International (2019)
- ASTM A606/A606M — Steel Sheet and Strip, Hot-Rolled and Cold-Rolled, with Improved Atmospheric Corrosion Resistance (Type 4) — ASTM International (2018)
- ASTM G101 — Estimating the Atmospheric Corrosion Resistance of Low-Alloy Steels — ASTM International (2020)
- GB/T 4171 — (Q355NH / Q235NH) — SAC / (2008)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
- ASM Handbook Vol.13C — Corrosion: Environments and Industries — ASM International (2006)
- COR-TEN A / COR-TEN B weathering steel data sheet — SSAB / ArcelorMittal (2022)
Property data is compiled from published supplier and standards handbooks and normalised for comparison; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.