Steel A588-GrC
Grade
ASTM A588 · UNS K11430
GrC = grade C
Alternate licensed chemistry supplied by some mills; same strength class as Grades A/B.
Values for the GrC condition
Other A588 tempers and conditions
A588 is listed in 8 conditions; see the grade overview at A588.
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 |
GrCThis page 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 |
What is A588-GrC?
A588-GrC is A588 in the GrC grade — alternate licensed chemistry supplied by some mills; same strength class as Grades A/B. A588-GrC 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). A588-GrC 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). HR is the default condition FabDigit quotes; GrC is available on request or by drawing note.
Advantages
- Conducts heat well — 52 W/m·K (30 BTU/hr·ft·°F), better than 98% of steel grades
- Good corrosion resistance — 34/100, better than 97% of steel grades
- Tough — resists crack growth — 125 MPa·√m (113.8 ksi·√in), better than 85% 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-GrC properties
Typical room-temperature values for A588-GrC; 22 are specific to this condition. Other listed values are A588 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
A588-GrC 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-GrC 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-GrC 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-GrC conducts electricity at 8.6 % IACS, better than 66% of steel grades.
Chemical & Environmental3
Corrosion resistance is poor (34/100), better than 97% of steel grades.
Sustainability4
Producing a kilogram of A588-GrC 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-GrC's machinability is good (55/100, better than 62% of steel grades); weldability very good (78/100); formability good (60/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with A588-GrC
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.
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.
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 | — |
A588-GrC — frequently asked
What is A588-GrC used for?
A588-GrC 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-GrC?
A588-GrC 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-GrC 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-GrC 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-GrC?
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-GrC 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-GrC?
A588-GrC 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.
Can FabDigit make parts in A588-GrC?
Yes — A588-GrC 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. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.