ASTM A709/A709M Grade 100W High-Strength Weathering Steel Coil
ASTM A709/A709M Grade 100W High-Strength Weathering Steel Coil for Bridges and Structures
Complete material properties and reference data for ASTM A709/A709M Grade 100W carbon and low-alloy high-strength steel coil, including chemistry, mechanical performance, physical properties, international equivalents, and application guidance.
Cold forming, bending, welding (with preheat and low-hydrogen electrodes), machining
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ASTM A709/A709M Grade 100W High-Strength Weathering Steel Coil Introduction
ASTM A709/A709M Grade 100W is a low-alloy, high-strength structural steel supplied as coil, primarily designed for welded bridges, buildings, and heavy-duty structural applications. Delivered in the quenched and tempered (Q&T) condition, it provides a minimum yield strength of 100 ksi (690 MPa) and enhanced atmospheric corrosion resistance (weathering characteristics, denoted by "W").
- High strength-to-weight ratio allows lightweight design.
- Weathering nature reduces maintenance costs; it forms a protective patina when used without paint coatings.
- Excellent notch toughness at low temperatures when specified, making it suitable for fracture-critical components.
- Good weldability with appropriate low-hydrogen procedures and preheating.
The grade is governed by ASTM A709/A709M and references the chemical and mechanical requirements of ASTM A514 Grade H, ensuring consistent performance in structural engineering.
ASTM A709/A709M Grade 100W High-Strength Weathering Steel Coil Chemical Composition
Chemical requirements are derived from ASTM A514/A514M Grade H, which is referenced by ASTM A709/A709M for Grade 100W to achieve the required strength and weathering resistance. Copper, chromium, and nickel provide atmospheric corrosion resistance, while vanadium and boron ensure hardenability and strength.
- Residual elements such as Nb, Ti, and Al may be present but are not defined with minimum limits in the base specification.
- Carbon equivalent (CE) is often controlled for weldability, typically CE ≤ 0.55.
| Element | Specification (%) | Remarks |
|---|---|---|
| C | 0.12 - 0.21 | Carbon |
| Mn | 0.80 - 1.10 | Manganese |
| Si | 0.40 - 0.70 | Silicon |
| P | ≤ 0.025 | Phosphorus |
| S | ≤ 0.025 | Sulfur |
| Cr | 0.40 - 0.65 | Chromium (weathering element) |
| Mo | 0.20 - 0.30 | Molybdenum |
| Cu | 0.20 - 0.35 | Copper (weathering element) |
| Ni | 0.30 - 0.70 | Nickel (weathering element) |
| V | 0.03 - 0.08 | Vanadium |
| B | 0.0005 - 0.005 | Boron (hardenability agent) |
ASTM A709/A709M Grade 100W High-Strength Weathering Steel Coil Thermal & Electrical Physical Properties
These values are nominal for quenched and tempered low-alloy steel of the 690 MPa class. They are not mandatory in ASTM A709/A709M but represent commonly accepted design data.
- Density may vary slightly with alloy content.
- Specific heat and thermal conductivity are temperature dependent; values provided are at room temperature.
| Property | Typical Value | Unit | Conditions |
|---|---|---|---|
| Density (ρ) | 7850 | kg/m³ | 20 °C |
| Elastic Modulus (E) | 200 | GPa | Room temperature |
| Shear Modulus (G) | 80 | GPa | Calculated from E and ν=0.3 |
| Poisson's Ratio (ν) | 0.30 | - | Elastic range |
| Coefficient of Thermal Expansion (α) | 12.2 | µm/m·°C | 20–100 °C |
| Thermal Conductivity (λ) | 40 | W/m·K | 20 °C |
| Specific Heat Capacity | 460 | J/kg·K | 20 °C |
| Electrical Resistivity (ρe) | 0.22 | µΩ·m | 20 °C |
ASTM A709/A709M Grade 100W High-Strength Weathering Steel Coil Mechanical Properties
Properties are derived from ASTM A709/A709M for Grade 100W (Q&T condition). Tensile requirements are mandatory for all products. Bending test parameters depend on product thickness. Charpy impact values are typically specified using supplementary requirement S5 per ASTM A673 for fracture-critical applications (Zone 2 common for bridges @ −18°C).
- Yield strength and tensile values apply to transverse or longitudinal specimens as agreed.
- Elongation is measured on a 2-inch (50 mm) gauge length for plates ≤ 3/4 in. or on an 8-inch (200 mm) gauge depending on product form; provided values are typical minimums.
| Property | Required Value | Unit | Test Conditions | |
|---|---|---|---|---|
| Yield Strength (ReH) | ≥ 690 | MPa | 0.2% offset, room temperature | |
| Yield Strength (ReH) | ≥ 100 | ksi | 0.2% offset, room temperature | |
| Tensile Strength (Rm) | 760 - 895 | MPa | Room temperature | |
| Tensile Strength (Rm) | 110 - 130 | ksi | Room temperature | |
| Elongation (A50) | ≥ 18 | % | in 2 in. (50 mm) gauge | |
| Elongation (A200) | ≥ 16 | % | in 8 in. (200 mm) gauge | Applicable for heavy plates |
| Bend Test (t=thickness) | 2t | - | Thickness ≤ 3/4 in. (19 mm) | |
| Bend Test | 2.5t | - | Thickness > 3/4 to 1-1/2 in. (19–38 mm) | |
| Bend Test | 3t | - | Thickness > 1-1/2 to 2-1/2 in. (38–64 mm) | |
| Charpy V-Notch (KV) | ≥ 27 | J | Longitudinal, @ −18°C (0°F), when specified per Zone 2 | |
| Charpy V-Notch (KV) | ≥ 20 | ft·lbf | Longitudinal, @ −18°C (0°F), when specified per Zone 2 |
ASTM A709/A709M Grade 100W High-Strength Weathering Steel Coil Complete Material Equivalents & Replacements
| Country / Region | Standard | Designation | Remarks |
|---|---|---|---|
| USA | ASTM A514/A514M | Grade H | Chemical basis for A709 100W; same strength class and weathering capabilities. |
| USA | ASTM A709/A709M | Grade 100W | Direct specification; structural steel for bridges. |
ASTM A709/A709M Grade 100W High-Strength Weathering Steel Coil Application Introduction
ASTM A709 Grade 100W combines very high strength with atmospheric corrosion resistance, ideal for weight-sensitive, long-life structures. It is used extensively in bridge engineering worldwide, especially in North America. The quenched and tempered condition gives superior mechanical properties while maintaining good toughness.
- When welding, low-hydrogen processes are mandatory; preheating up to 150–200°C is typical for thicknesses above 25 mm.
- The material can be used unpainted if periodic wet/dry cycles allow a stable patina; otherwise painting is possible with proper surface preparation.
Product Applications: Bridge girders, box sections, arch ribs, Welded columns and trusses for high-rise buildings, Boom sections, outriggers, and frames for mobile cranes, Mining dump bodies and excavator buckets (wear and impact parts), Railway bridge superstructures
Processed into products: Flanges and webs of fabricated plate girders, Splice plates and connection angles, Bearing stiffeners, Heavy bending plates for transition zones, Load-bearing nodes in space frames
Application industries: Bridge and highway construction, Offshore and marine structures (above water line), Heavy machinery and crane manufacturing, Architectural and structural engineering, Mining equipment and heavy transport
ASTM A709/A709M Grade 100W High-Strength Weathering Steel Coil Similar/Comparable Materials
| Country / Region | Standard | Designation | Remarks |
|---|---|---|---|
| EU | EN 10025-6 | S690QL / S690QL1 | High-strength quenched and tempered steel, no guaranteed weathering resistance. |
| China | GB/T 28909 | Q690NH | Weathering high-strength structural steel, similar strength level, different chemistry. |
| Japan | JIS G 3128 | SHY685 | High yield strength weathering steel plate for welded structures (685 MPa YS). |
Notes:
All data are based on ASTM A709/A709M and referenced ASTM A514 Grade H specifications. Actual values may be subject to customer-supplier agreements and supplementary requirements. Pre- and post-weld heat treatment recommendations depend on thickness and service conditions; always consult relevant welding codes (e.g., AWS D1.5 for bridges).
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