What is ASTM A573 Grade 70?
ASTM A573 Grade 70 is the highest strength grade structural steel plate specified under ASTM A573/A573M, belonging to the carbon-manganese-silicon fully killed steel series. Manufactured using fine-grain practice, it delivers superior notch toughness over conventional carbon steels while maintaining high structural strength.
In practical engineering terms, if you are currently using standard carbon steels like ASTM A36 but require higher yield/tensile strength, improved low-temperature impact properties, or better dynamic load resistance-without the price premium of high-strength low-alloy (HSLA) steels-ASTM A573 Grade 70 serves as the ideal step-up alternative. It offers performance approaching low-alloy grades at a near-carbon steel cost point.
Why Choose ASTM A573 Grade 70 Carbon Plate?
Three Key Competitive Advantages for Structural Safety and Cost Efficiency
Higher Strength, Reduced Dead Weight
With a minimum yield strength of 290 MPa (42 ksi)-16% higher than standard ASTM A36 carbon steel-A573 Grade 70 allows for reduced plate thickness under equivalent load conditions. This lowers overall structural dead load, delivering direct savings on material costs and freight.
Superior Toughness, Greater Safety Margins
Produced using fully killed, fine-grain practice, it offers vastly superior notch toughness compared to rimmed or semi-killed steels. Charpy V-Notch (CVN) impact testing can be specified as a supplementary requirement, ensuring reliable performance in cold-climate applications and under dynamic loading conditions.
Excellent Weldability, Lower Fabrication Costs
Formulated with a balanced C-Mn-Si chemical composition and a controlled carbon equivalent, this grade exhibits exceptionally low susceptibility to cold cracking. It can be fabricated using standard structural welding procedures without requiring complex preheating protocols or specialized consumables, minimizing shop fabrication costs.
ASTM A573 Grade 70 Carbon Structural Steel Plate Specification
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Material: |
ASTM A573 Grade 70 Carbon Structural Steel Plate |
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Thickness: |
4.8 – 38.1 mm (standard maximum 40mm) |
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Width: |
1200 – 3050 mm |
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Length: |
3000 – 25900 mm |
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Surface: |
Clean,finished, blasting and painting or as your request |
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Delivery: |
Hot Rolled, Controlled Rolling,Normalizing,Annealing, Tempering,Quanching, Q+T... |
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Packing: |
Standard export package |
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Trade Term: |
FOB,CFR,CNF,CIF,EXW... |
Regarding extra-thick steel plates: The ASTM A573 standard specifies a maximum thickness of 40 mm. If your project requires thicker plates, we can provide a customized R&D solution; however, performance must be separately evaluated and verified, and full compliance with the A573 standard cannot be guaranteed.
ASTM A573 Grade 70 Carbon Steel Plate Chemical Composition
| Element | Content |
|---|---|
| Carbon (C) | ≤ 0.28% |
| Manganese (Mn) | 0.85–1.20%* |
| Silicon (Si) | 0.15–0.40%* |
| Phosphorus (P) | ≤ 0.030% |
| Sulfur (S) | ≤ 0.030% |
| Aluminum (Al) | ≥ 0.020%* |
ASTM A573 Grade 70 Carbon Steel Plate Mechanical Property
| Mechanical Property | Imperial Value | Metric Value |
|---|---|---|
| Tensile Strength | 70–90 ksi | 485–620 MPa |
| Yield Strength (Minimum) | ≥ 42 ksi | ≥ 290 MPa |
| Elongation (8 in / 200 mm) | ≥ 18% | ≥ 18% |
| Elongation (2 in / 50 mm) | ≥ 21% | ≥ 21% |
Processing and Fabrication Guidelines of ASTM A573 Grade 70 Structural Steel Plate
Welding Recommendations Low-hydrogen welding processes (SMAW, FCAW, SAW) are recommended. For plate thicknesses exceeding 25 mm (1 in.) or ambient temperatures below 0°C (32°F), appropriate preheating (100–150°C / 210–300°F) is advised. Select filler metals to match the strength of the base metal.
Cold Forming Exhibits good cold formability. Due to the higher strength of ASTM A573 Grade 70 compared to ASTM A36, a larger minimum inside bend radius is recommended (typically 2T to 3T or greater, depending on thickness and bend angle).
Thermal Cutting Plasma, laser, and oxy-fuel cutting are all suitable methods. Control heat input during thermal cutting to prevent excessive edge hardening that could impact downstream processing.
Heat Treatment Typically supplied and used in the as-rolled condition. Where enhanced toughness uniformity is required, normalizing (as-supplied) can be specified. Quenching and tempering (Q&T) heat treatment is not recommended for ASTM A573 grades.
Our technical services team-comprising experienced metallurgical and welding engineers-provides full technical support, including Welding Procedure Specifications and Procedure Qualification Records (WPS/PQR), forming and bending guidelines, and heat treatment consultation.
Contact our technical sales team to discuss your project requirements. →
Typical Applications for ASTM A573 Grade 70 Steel Plates
Bridges and Structural Steelwork Bolted, welded, and riveted structures including bridge main girders, primary load-bearing structural members, and industrial plant frameworks.
Storage Tanks and Vessel Fabrication Shell plates and bottom plates for welded storage tanks, including oil storage tanks, water tanks, chemical tanks, and industrial storage silos.
Heavy Construction Machinery Crane structural components, excavator booms, mining equipment frames, and heavy equipment bases.
Transportation Equipment Truck and trailer frames, railcar body structures, shipping container frames, and vessel superstructures.
Energy Infrastructure Wind turbine tower segments, power plant support structures, solar racking systems, and transmission tower components.
General Machinery Manufacturing Agricultural machinery, material handling equipment, automated production line frameworks, and general structural steel fabrications.
Available Testing Services
To ensure every plate shipment complies fully with ASTM A573/A573M standards, we provide comprehensive Quality Assurance and Quality Control (QA/QC) inspection services covering chemical composition, mechanical properties, and non-destructive testing (NDT):
- Chemical Analysis: Spectrometric analysis to verify elements including C, Mn, Si, P, S, and Al for exact heat analysis compliance.
- Tensile Testing: Determination of tensile strength, yield strength, and elongation to verify mechanical property requirements.
- Charpy V-Notch (CVN) Impact Testing: Low-temperature impact testing at specified temperatures to evaluate notch toughness.
- Ultrasonic Examination: Ultrasonic Testing (UT) to detect internal discontinuities, with acceptance criteria per ASTM A578 / ASTM A435.
- Dimensional and Surface Inspection: Comprehensive inspection of thickness, width, length, flatness, and surface quality conditions.
- Third-Party Inspection (TPI): Independent third-party witnessing and certification by internationally recognized agencies such as SGS, BV, and Applus+.
Below are the third-party inspection test results for ASTM A573 Grade 70 steel plates, confirming 100% compliance with all specified requirements.
Click to View Full Inspection Report (PDF)
Why Choose GNEE Steel?
- We maintain a stock of thousands of tons of steel, with same-day shipping for standard specifications. Small trial orders and samples are supported; minimum order quantities are not mandatory.
- Each batch comes with an original manufacturer's material certificate and a third-party testing report, ensuring full traceability of chemical composition and mechanical properties.
- Export standard packaging: Moisture-proof kraft paper wrapping + reinforced steel frame pallet + seaworthy metal outer shell, avoiding rust and deformation during long sea transit to overseas construction yards
Find the right steel plate for your project.
Not sure which grade to choose? Need a quote or a sample? Let us know your requirements, and we will respond within 24 hours.
FAQ
What is the yield strength of ASTM A573 Grade 70?
The minimum yield strength of ASTM A573 Grade 70 structural carbon steel plate is 42 ksi (42,000 psi or 290 MPa). Note that the "70" in the grade designation refers to its minimum tensile strength range of 70–90 ksi, not its yield strength.
What is the maximum standard thickness for ASTM A573 Grade 70 plate?
The maximum standard thickness for ASTM A573 Grade 70 plate is 1.5 inches (38.1 mm). Per the official ASTM specification, this standard limits the carbon-manganese-silicon plates to a cap of 1.5 inches for applications requiring improved notch toughness at atmospheric temperatures.
What is the delivery condition for ASTM A573 Grade 70?
ASTM A573 Grade 70 steel plates are normally supplied in the as-rolled condition, but can also be delivered in a normalized or thermomechanically controlled rolled (TMCP) state depending on thickness requirements and specific buyer purchases or supplemental requirements.
