What Is ASTM A606 Type 4 Corten Steel Plate?
ASTM A606 Type 4 Corten Steel Plate is a high-strength, low-alloy flat-rolled steel with improved atmospheric corrosion resistance. It contains an alloy system selected to develop a dense, adherent rust patina when the material is correctly exposed to alternating wet and dry conditions.
The patina slows further corrosion and allows many architectural and miscellaneous structural applications to use the steel without conventional painting.
The formal standard is ASTM A606/A606M, whose exact scope is high-strength, low-alloy hot-rolled and cold-rolled sheet and strip, supplied in cut lengths or coils.
Buyers and suppliers often use A606 Type 4 plate as a commercial search term, but the MTC should identify the certified product form and the applicable standard edition.
Under ASTM A606/A606M-25, hot-rolled cut lengths are covered at ordered thicknesses below 0.230 in. [6.0 mm], while hot-rolled coils may be ordered at 0.230 in. [6.0 mm] and above. A thick structural plate requirement should therefore be reviewed against ASTM A588/A588M, ASTM A871/A871M or the project specification instead of being assumed to be A606.
ASTM A606 Type 4 Corten Steel Standard Specification
| ASTM A606 Type 4 item | Specification information |
|---|---|
| Exact designation | ASTM A606 Type 4 / ASTM A606M Type 4 |
| Current standard reference | ASTM A606/A606M-25; the purchase order must identify the required edition |
| Material category | High-strength, low-alloy flat-rolled steel with improved atmospheric corrosion resistance |
| Standard product forms | Hot-rolled sheet and strip; cold-rolled sheet and strip; cut lengths and coils |
| Corrosion requirement | Minimum corrosion-resistance index of 6.0 calculated using ASTM Guide G101 |
| Density for weight calculation | Approximately 7,850 kg/m³ |
| Common delivery conditions | Hot rolled as rolled; annealed or normalized when ordered; cold rolled |
| Standard dimensional references | ASTM A568/A568M and other general requirements referenced by the purchase specification |
Type 4 contains additional alloying elements and provides atmospheric corrosion resistance substantially better than carbon steel with or without copper addition. When exposure and detailing permit stable patina development, it can be used bare in many applications.
ASTM A606 Type 4 Corten Steel Chemical Composition
| ASTM A606 Type 4 chemical item | Cast/heat analysis | Product verification analysis |
|---|---|---|
| Carbon, maximum | 0.22% | 0.26% |
| Manganese, maximum | 1.25% | 1.30% |
| Sulfur, maximum | 0.040% | 0.060% |
| Additional weathering elements | Mill-designed combination, commonly involving Cu, Cr, Ni, Si and/or P | Must support the Type 4 corrosion-performance requirement |
| Corrosion-resistance index | Minimum 6.0 under ASTM Guide G101 | Confirmed through the producer's chemistry calculation/documentation |
For heat compositions with carbon no more than 0.15%, the standard permits a higher manganese maximum subject to its stated limits.
ASTM A606 Type 4 Corten Steel Mechanical Properties
| ASTM A606 Type 4 product/condition | Minimum yield strength | Minimum tensile strength | Minimum elongation in 2 in. [50 mm] |
|---|---|---|---|
| Hot rolled, as rolled | 50 ksi [340 MPa] | 70 ksi [480 MPa] | 22% |
| Hot rolled, annealed or normalized | 45 ksi [310 MPa] | 65 ksi [450 MPa] | 22% |
| Cold rolled, cut length or coil | 45 ksi [310 MPa] | 65 ksi [450 MPa] | 22%* |
ASTM A606 Type 4 Corten Steel Sizes and Tolerances
ASTM A606 is primarily a sheet, strip and coil standard. Available dimensions vary by mill and order quantity. The following ranges are practical sourcing references, not universal ASTM limits.
| ASTM A606 Type 4 supply form | Typical sourcing range | Common widths/lengths |
|---|---|---|
| Cold-rolled sheet/coil | Approximately 0.5–3.0 mm | Width 600–1,500 mm; cut lengths to order |
| Hot-rolled sheet/coil | Approximately 1.5–10.0 mm | Width 800–1,900 mm commonly available from selected mills |
| Standard cut sheets | 1.5–6.0 mm commonly requested | 1,219 × 2,438 mm, 1,250 × 2,500 mm and 1,500 × 3,000 mm |
| Coil supply | Mill-dependent | Coil ID, OD and maximum coil weight must be agreed |
| Custom blanks/panels | Drawing-dependent | Laser-cut, sheared, perforated or folded parts |
Send the required thickness, width, length, monthly tonnage and acceptable tolerance. We can compare standard coil widths with custom cutting to identify the lowest-scrap, best-landed-cost option.
ASTM A606 Type 4 Hot-Rolled and Cold-Rolled Surface
| ASTM A606 Type 4 surface | Standard/commercial description | Purchasing consideration |
|---|---|---|
| Hot rolled, as rolled | Mill-scale surface unless another finish is ordered | Economical for fabrication and natural weathering |
| Hot rolled, pickled | Scale removed by pickling | Cleaner surface; availability must be confirmed |
| Blast-cleaned | Mechanically cleaned active surface | Suitable before pre-rusting, coating or fabrication |
| Cold rolled, matte | Smooth, dull cold-rolled finish | Suitable for thin architectural sheet and formed parts |
| Pre-rusted | Accelerated initial orange-brown/brown patina | Colour range and reference sample should be approved |
| Pre-rusted and sealed | Patina plus transparent sealing system | Confirm gloss, UV resistance, runoff control and maintenance |
ASTM A606 Type 4 Corten Steel Cutting and Fabrication
ASTM A606 Type 4 can be laser cut, sheared, plasma cut, punched, drilled, roll formed, bent and welded. Laser cutting and shearing are commonly used for roofing, cladding, screens and precision blanks. Coil slitting and cut-to-length processing can reduce material waste for repeat production.
The steel is generally weldable using a procedure suited to its actual chemistry, thickness, end use and service temperature. Welding consumables should be selected according to the design strength and required weathering appearance.
Thick material, highly restrained joints, low-temperature welding and fatigue-sensitive structures require WPS/PQR review rather than a generic filler recommendation.
Pre-rusting is normally performed after cutting, perforating, bending and welding so exposed edges and heat-affected areas can develop a compatible appearance. Oil, adhesive, weld spatter, temporary markings and mixed-metal contamination should be removed before weathering treatment.
ASTM A606 Type 4 Corten Steel MTC and Testing
Each batch can be supplied with an EN 10204 3.1 MTC or a mill test report acceptable under the purchase contract. The certificate should identify ASTM A606 Type 4, standard edition, heat number, product form, dimensions, heat chemistry and tensile results.
| ASTM A606 Type 4 inspection | Purpose |
|---|---|
| MTC and heat-number review | Confirms grade identity and traceability |
| Chemical analysis | Confirms heat composition and alloy design |
| G101 corrosion-index documentation | Confirms the Type 4 minimum index requirement |
| Tensile test | Verifies yield strength, tensile strength and elongation |
| Thickness/width/length inspection | Confirms ordered dimensional tolerances |
| Flatness, camber and surface inspection | Confirms sheet/coil geometry and appearance |
| PMI/spectrometer verification | Optional independent check of major alloy elements |
| Third-party inspection | SGS, BV or another agreed agency when ordered |
Charpy impact testing and ultrasonic plate testing are not universal base requirements for every A606 sheet order. If the application requires them, the test temperature, acceptance value, sampling frequency and applicable method must be written into the order.
ASTM A606 Type 4 Corten Steel Plate Weight and Container Loading
Theoretical weight is calculated using a density of approximately 7,850 kg/m³:
Weight (kg) = thickness (mm) × width (m) × length (m) × 7.85
| ASTM A606 Type 4 sheet size | Approximate weight per sheet | Approximate sheets in 25 t net steel weight* |
|---|---|---|
| 1.5 × 1,219 × 2,438 mm | 35.0 kg | 714 |
| 2.0 × 1,250 × 2,500 mm | 49.1 kg | 509 |
| 3.0 × 1,500 × 3,000 mm | 106.0 kg | 235 |
| 5.0 × 1,500 × 3,000 mm | 176.6 kg | 141 |
| 6.0 × 1,500 × 6,000 mm | 423.9 kg | 58 |
Indicative only. The final quantity depends on actual mill thickness, pallet/skid weight, moisture protection, container payload, shipping-line rules and road limits.
A 20-foot container commonly carries about 24–27 tonnes of steel, but thin sheets may reach volume, handling or pallet-height limits before the maximum weight.
For coil orders, the buyer should state maximum coil weight, coil ID/OD, unloading equipment and whether eye-to-sky or eye-to-side loading is required.
ASTM A606 Type 4 Corten Steel Applications
| ASTM A606 Type 4 application | Typical product form | Key design consideration |
|---|---|---|
| Architectural façades and rainscreens | Cut sheet, perforated or folded panels | Flatness, runoff control, fixing details and colour variation |
| Roofing and wall cladding | Sheet or slit coil | Drainage, seams, thermal movement and underside ventilation |
| Containers and railcars | Hot-rolled sheet/coil | Formability, welding and repeat production tolerances |
| Screens, fences and signage | Laser-cut or perforated sheet | Edge safety, distortion and visible surface |
| Planters and landscape products | Folded/welded sheet | Soil-side drainage, staining and wet exposure |
| Ducts, hoppers and industrial housings | Formed sheet | Abrasion, chemicals and service-temperature assessment |
| Light structural components | Hot-rolled sheet/coil | Load calculation and standard product-form limits |
ASTM A606 Type 4 should not automatically be used bare in continuously wet areas, buried zones, marine splash zones, heavy de-icing-salt exposure or sheltered crevices without wet/dry cycles. These conditions may require coatings, drainage redesign, corrosion allowance or another material.
For bridge primary members and heavy load-bearing plate, verify whether ASTM A709 Grade 50W, ASTM A588 or another bridge/plate specification is required rather than relying on the commercial phrase A606 plate.
GNEE can supply raw ASTM A606 Type 4 sheet and coil, cut-to-size blanks, perforated/folded panels, Pre-Rusted Corten Steel and Pre-Weathered Corten Steel. Small material or surface samples can be arranged for identification, forming trials, welding trials and patina approval.
Send your specification, BOM or drawing today. We will return a quotation package covering the correct ASTM product form, available mill size, MTC/testing scope, theoretical weight, processing route, loading plan, lead time and FOB/CIF/DAP price.
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