ASTM A656 Grade 70 High-Strength Low-Alloy Steel Coil
ASTM A656 Grade 70 High-Strength Low-Alloy Steel Coil for Structural and Forming Applications
Comprehensive technical data for ASTM A656/A656M Grade 70 carbon and low-alloy high-strength structural steel coil, including chemical composition, mechanical and physical properties, international equivalents, and application guidance.
Hot rolling, cold forming, bending, stamping, welding, machining, and punching
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ASTM A656 Grade 70 High-Strength Low-Alloy Steel Coil Introduction
ASTM A656/A656M Grade 70 is a hot-rolled, high-strength low-alloy (HSLA) structural steel with improved formability supplied in coil or cut lengths. It is microalloyed with vanadium, niobium, or titanium to achieve a minimum yield strength of 70 ksi (485 MPa) while maintaining good weldability and toughness. The steel is characterized by its fine grain structure and excellent strength-to-weight ratio, making it suitable for weight-critical structural applications where cold forming operations such as bending, flanging, and moderate drawing are required.
- Minimum yield strength: 70 ksi (485 MPa)
- Improved formability compared to conventional structural steels
- Good weldability using standard methods
- Supplied in as-rolled, normalized, or stress-relieved condition
- Available in a wide range of thicknesses up to 1.5 in. (40 mm)
Typical uses include truck frames, crane booms, agricultural equipment, and other load-bearing components.
ASTM A656 Grade 70 High-Strength Low-Alloy Steel Coil Chemical Composition
Chemical composition limits per ASTM A656/A656M for Grade 70. The steel is microalloyed with one or more of the elements vanadium, niobium, and titanium to achieve strength and formability. The sum of Nb+V+Ti shall not exceed 0.15%. Elements not listed, such as copper, nickel, chromium, and molybdenum, may be present as residuals with maximum limits specified in the standard unless otherwise agreed.
| Element | Standard Value (max, unless range given) | Remarks |
|---|---|---|
| Carbon (C) | 0.18% | Maximum |
| Manganese (Mn) | 1.65% | Maximum |
| Phosphorus (P) | 0.025% | Maximum |
| Sulfur (S) | 0.035% | Maximum |
| Silicon (Si) | 0.60% | Maximum |
| Vanadium (V) | 0.10% | Maximum; sum of Nb+V+Ti ≤ 0.15% |
| Niobium (Nb) | 0.08% | Maximum; sum of Nb+V+Ti ≤ 0.15% |
| Titanium (Ti) | 0.10% | Maximum; sum of Nb+V+Ti ≤ 0.15% |
| Nitrogen (N) | 0.020% | Maximum (when reported) |
ASTM A656 Grade 70 High-Strength Low-Alloy Steel Coil Thermal and Electrical Physical Properties
Physical properties are not mandated by ASTM A656/A656M. The values provided are typical for carbon/low-alloy structural steels and are suitable for engineering calculations. Actual values may vary slightly depending on exact composition and production route.
- Density and modulus values are based on standard steel data.
- Thermal expansion, conductivity, and specific heat are averaged over the indicated temperature ranges.
- Electrical resistivity is at room temperature.
| Property | Standard Value (Typical) | Unit | Test Condition / Temperature |
|---|---|---|---|
| Density (ρ) | 7.85 | g/cm³ | 20 °C |
| Elastic Modulus (E) | 200 | GPa | Room temperature |
| Shear Modulus (G) | 80 | GPa | Room temperature |
| Poisson's Ratio (ν) | 0.30 | — | Room temperature |
| Thermal Expansion Coefficient (α) | 11.7 | 10⁻⁶ /K | 20–100 °C |
| Thermal Conductivity (λ) | 45 | W/(m·K) | 100 °C |
| Specific Heat Capacity | 480 | J/(kg·K) | 20 °C |
| Electrical Resistivity (ρ_e) | 0.15–0.20 | μΩ·m | Room temperature |
ASTM A656 Grade 70 High-Strength Low-Alloy Steel Coil Mechanical Properties
Tensile properties for Grade 70 as specified in the standard. Values depend on plate thickness. Elongation requirements are provided for both 8-inch (200 mm) and 2-inch (50 mm) gauge lengths. Impact toughness is not mandatory unless supplementary requirements are invoked. Bending performance is generally excellent, but specific bend test criteria are not included in the base specification.
| Property | Standard Requirement | Unit | Test Condition |
|---|---|---|---|
| Yield Strength (ReH) | ≥ 70 [485] | ksi [MPa] | All thicknesses up to 1.5 in. (40 mm) |
| Tensile Strength (Rm) | ≥ 80 [550] | ksi [MPa] | All thicknesses |
| Elongation (A) in 8 in. [200 mm] | ≥ 14 | % | All thicknesses |
| Elongation (A) in 2 in. [50 mm] | ≥ 18 | % | Thickness ≤ 0.75 in. (20 mm) |
| Elongation (A) in 2 in. [50 mm] | ≥ 18 | % | Thickness > 0.75 in. to 1.5 in. (20–40 mm) |
ASTM A656 Grade 70 High-Strength Low-Alloy Steel Coil Completely Equivalent Material Standards and Direct Substitute Grades
| Country/Region | Standard | Grade | Remarks |
|---|---|---|---|
| USA | ASTM A656/A656M | Grade 70 | Original specification; hot-rolled HSLA coil/plate with improved formability |
| European Union | EN 10149-2 | S500MC (1.0984) | Closest match in terms of minimum yield strength (500 MPa) and high formability; S550MC (YS 550 MPa) may also be considered |
| Japan | JIS G3134 | SPFH590 | HSLA automotive structural steel with YS ≥ 440 MPa, TS ≥ 590 MPa; similar forming characteristics |
| China | GB/T 1591 | Q500D | High-strength low-alloy structural steel; chemical and mechanical requirements differ slightly |
ASTM A656 Grade 70 High-Strength Low-Alloy Steel Coil Application Introduction
ASTM A656 Grade 70 is designed for structural applications that require a combination of high strength, good weldability, and enhanced formability. Its microalloyed composition ensures fine grain size and consistent performance during cold forming operations such as press braking, roll forming, and stretch flanging. It is not intended for heat treatment to improve properties—strength is achieved through controlled rolling and microalloy precipitation.
Product Applications: Roll-formed structural sections, Pressed and welded assemblies, Cut-to-length plates for fabrication, Slit coils for progressive stamping
Processed into products: Truck frame rails and cross members, Crane boom chords and lacing, Tow hitches and drawbars, Loader arms and excavator booms, Agricultural implement frames (plows, cultivators), Railway bogie frames, Tube and pipe for structural applications
Application industries: Transportation (trucks, trailers, railcars), Construction and earthmoving equipment, Agricultural machinery, Material handling and crane manufacturing, Structural engineering, Off-highway vehicle manufacturing
ASTM A656 Grade 70 High-Strength Low-Alloy Steel Coil Similar or Alternative Material Recommendations
| Country/Region | Standard | Grade | Remarks |
|---|---|---|---|
| International | ISO 6930-2 | FeE500 | High yield strength steel for cold forming; YS ≥ 500 MPa, TS 550–700 MPa; similar application scope |
| USA | ASTM A1011/A1011M | Grade 70 HSLAS | Hot-rolled HSLA steel for structural uses; slightly different formability requirements |
| USA | ASTM A572/A572M | Grade 70 | HSLA structural steel, but without explicit formability guarantees; often used as an alternate for A656 when bending is less critical |
| European Union | EN 10025-3 | S460N/NL | Normalized fine-grain structural steel; lower strength but higher toughness; can replace in some applications |
Notes:
Weldability: This grade is readily weldable by all common methods (SMAW, GMAW, SAW) with low hydrogen practices recommended when thickness exceeds 0.5 in. (12 mm). Surface condition: Supplied as hot-rolled with mill scale; pickled and oiled finish available upon request. Supplementary requirements: Impact testing (Charpy V-notch) can be specified under ASTM A6/A6M Supplementary Requirement S2 if required. Formability: Minimum bend radii for cold forming should follow the recommendations in ASTM A6/A6M or be agreed upon. When ordering, the purchaser may specify coil width, thickness tolerance, and edge condition. Certification: Mill test reports are provided in accordance with EN 10204 3.1 or ASTM A6/A6M.
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