Steel A242
ASTM A242 · UNS K11510
A242 is the original copper-bearing atmospheric-corrosion-resistant HSLA plate steel (A242 Type 1, UNS K11510), the predecessor of modern Corten A and broadly comparable to Q355NH.
Reference datasheet — A242 is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
Values for the HR-50 condition
A242 tempers and conditions
A242 is supplied in 5 conditions, soft to hard. HR-50 is the default FabDigit quotes; the values on this page are for it.
Compare all 5 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Hot Rolled, 38–100 mm | Heavy plate class for thick bridge and structural sections; lowest strength grade of A242. | 315 | 465 | 23 | 145 HB | 8.5 % IACS |
Hot Rolled, 19–38 mm | Medium plate thickness class — same chemistry, strength de-rated by section size. | 340 | 490 | 24 | 150 HB | 8.5 % IACS |
Normalized | Specified for thick plate or low-temperature service where refined grain size and higher CVN toughness are needed. | 360 | 500 | 26 | 150 HB | 8.5 % IACS |
HR-50Default Hot Rolled, t ≤ 19 mm | Standard as-rolled plate, sheet and shapes up to 3/4 in — the normally stocked weathering-steel condition. | 370 | 510 | 24 | 155 HB | — |
Cold rolled | Thin sheet/coil equivalents (A606-type) for cladding, containers and railcar panels where extra strength and flatness are wanted. | 400 | 520 | 20 | 170 HB | 8.5 % IACS |
Supply forms, finishes and certifications
Ways A242 is supplied — form, process route, surface or paperwork — without a datasheet of their own. The property values above apply.
| Option | What it is | Type |
|---|---|---|
PW | Pre-weathered / accelerated-patina finish | Surface finish |
What is A242?
A242 is the original copper-bearing atmospheric-corrosion-resistant HSLA plate steel (A242 Type 1, UNS K11510), the predecessor of modern Corten A and broadly comparable to Q355NH. Default hot-rolled properties are 370 MPa yield, 510 MPa tensile, 24 % elongation and about 155 HB, and it is supplied as plate, bar and structural shapes for bare, paint-free outdoor service. The protective patina only develops under alternating wetting and drying, so buried, immersed or salt-spray exposures are unsuitable and rust run-off can stain adjacent surfaces. A606 Type 4 covers the same weathering chemistry in sheet and coil gauges. A242 has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,450°C (2,642 °F). A242 has a yield strength of 370 MPa (53.7 ksi) and a tensile strength of 510 MPa (74 ksi) — weaker than 70% of steel grades. Elongation at break is 24% and the elastic modulus is 200 GPa (29 Msi).
What is A242 used for?
- railcar bodies
- bridges
- outdoor structural plate
- architectural weathering panels
Advantages
- Good corrosion resistance — 35/100, better than 97% of steel grades
- Low embodied carbon — 1.9 kg CO₂/kg, better than 92% of steel grades
- Tough — resists crack growth — 120 MPa·√m (109.2 ksi·√in), better than 81% of steel grades
- Forms and bends easily — 65/100, better than 81% of steel grades
- Conducts heat well — 48 W/m·K (27.7 BTU/hr·ft·°F), better than 79% of steel grades
Limitations
- Hard to polish — 40/100, worse than 96% of steel grades
A242 properties
Typical room-temperature values for A242-HR-50; bars are the position among steel grades.
Physical3
A242 has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,450°C (2,642 °F).
Mechanical16
A242 has a yield strength of 370 MPa (53.7 ksi) and a tensile strength of 510 MPa (74 ksi) — weaker than 70% of steel grades. Elongation at break is 24% and the elastic modulus is 200 GPa (29 Msi).
Thermal6
A242 is rated for continuous service to 350°C (662 °F). It conducts heat at 48 W/m·K (27.7 BTU/hr·ft·°F), better than 79% of steel grades. Thermal expansion is 11.7 µm/m·K (6.5 µin/in·°F).
Electrical3
A242 conducts electricity at 8.5 % IACS, better than 63% of steel grades.
Chemical & Environmental3
Corrosion resistance is fair (35/100), better than 97% of steel grades.
Sustainability4
Producing a kilogram of A242 takes about 25 MJ of energy and emits 1.9 kg of CO₂ — less than 82% of steel grades. Typical recycled content is 30%.
Manufacturability7
A242's machinability is good (58/100, better than 75% of steel grades); weldability very good (80/100); formability good (65/100).
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. A242 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with A242
Is A242 easy to machine?
Machines like a 350 MPa-yield HSLA steel (~60 % of 1212); use rigid setups and sharp carbide, mild work-hardening and stringy chips at low feeds.
Can A242 be welded?
Readily welded by SMAW/GMAW/SAW; use weathering-matching Cu-Ni-Cr consumables (e.g. E80xx-W, ER80S-G) so the weld patinas with the base metal, preheat 50–100 °C on thick or high-P heats.
Can A242 be formed, bent or molded?
Cold bend with r ≥ 2t transverse to rolling direction; hot form 900–1100 °C and air cool, avoid forming in the 250–400 °C blue-brittle range.
A242 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 |
|---|---|---|
| CA242 Type 1 max | ≤ 0.15 | 0.11 |
| Mn | ≤ 1 | 0.4 |
| PP deliberately used for patina stabilization (Corten A style) | ≤ 0.15 | 0.09 |
| S | ≤ 0.05 | 0.02 |
| Sitypical Corten A / Q355NH practice, not fixed by A242 | 0.15 – 0.75 | 0.4 |
| Cu0.20 % min required by A242 | 0.2 – 0.55 | 0.35 |
| Crtypical weathering addition | 0.3 – 1.25 | 0.7 |
| Nitypical weathering addition | ≤ 0.65 | 0.3 |
| Fe | balance |
What surface finishes work on A242?
Normally left bare to develop its own patina — needs alternating wet/dry exposure and free drainage; if painted, blast to SA 2.5 and use a zinc-rich epoxy system, and detail to prevent rust-run staining of adjacent concrete.
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).
Organic Coating
Black / Phosphate
Thermal Spray
Equivalent designations
Standards and trade names that resolve to Steel A242 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- UNS
- K11510
- ASTM
- A242 Type 1
- Similar grades
- Q355NH
How much does A242 cost?
A242 is a budget-cost steel ($), cheaper than about 90% 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.
A242 — frequently asked
What is A242 used for?
A242 is typically used for railcar bodies, bridges, outdoor structural plate and architectural weathering panels. In short: original weathering steel plate; paint-free outdoor service; corten A predecessor grade.
What is the yield strength of A242?
A242 has a typical yield strength of 370 MPa (53.7 ksi) and a tensile strength of 510 MPa (74 ksi) — weaker than 70% of steel grades. Strength varies by condition: see the 5 listed tempers.
Is A242 easy to machine?
Reasonably — machinability is rated good (58/100, better than 75% of steel grades). Machines like a 350 MPa-yield HSLA steel (~60 % of 1212); use rigid setups and sharp carbide, mild work-hardening and stringy chips at low feeds.
Can A242 be welded?
Yes — weldability is rated very good (80/100). Readily welded by SMAW/GMAW/SAW; use weathering-matching Cu-Ni-Cr consumables (e.g. E80xx-W, ER80S-G) so the weld patinas with the base metal, preheat 50–100 °C on thick or high-P heats.
What surface finishes work on A242?
Normally left bare to develop its own patina — needs alternating wet/dry exposure and free drainage; if painted, blast to SA 2.5 and use a zinc-rich epoxy system, and detail to prevent rust-run staining of adjacent concrete.
Can A242 be formed, bent or molded?
Cold bend with r ≥ 2t transverse to rolling direction; hot form 900–1100 °C and air cool, avoid forming in the 250–400 °C blue-brittle range.
What is the maximum service temperature of A242?
A242 is rated for continuous use to about 350°C (662 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between A242 HR-50 and A242 HR-42?
HR-50 is the default condition — standard as-rolled plate, sheet and shapes up to 3/4 in — the normally stocked weathering-steel condition. HR-42: heavy plate class for thick bridge and structural sections; lowest strength grade of A242. Yield strength is 370 MPa in HR-50 versus 315 MPa in HR-42.
How much does A242 cost?
A242 is a budget-cost steel ($), cheaper than about 90% 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.
Sources
- ASTM A242/A242M — High-Strength Low-Alloy Structural Steel — ASTM International (2018)
- ASTM G101 — Estimating Atmospheric Corrosion Resistance of Low-Alloy Steels — ASTM International (2020)
- GB/T 4171 (Q355NH etc.) — SAC (2008)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
- ASM Handbook Vol.13B — Corrosion: Materials — ASM International (2005)
- COR-TEN A / COR-TEN B weathering steel data — U.S. Steel / SSAB (2020)
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.