High-Strength Connections: A Guide to ASTM A490 Bolts
ASTM A490 bolts are high-strength, quenched and tempered alloy steel fasteners designed for structural applications requiring exceptional tensile strength. These bolts are commonly used in steel-to-steel connections and provide reliable performance in demanding construction projects.
What is ASTM A490?
ASTM A490 is a specification for heavy hex structural bolts made from alloy steel, offering a minimum tensile strength of 150 ksi. These bolts are intended for structural connections and are characterized by shorter thread lengths to prevent threads from being in shear planes. In 2016, ASTM A490 was incorporated into ASTM F3125 as Grade A490, but the original designation is still widely used in the industry.
Key Properties of ASTM A490 Bolts
Material: Quenched and tempered alloy steel.
Tensile Strength: 150–173 ksi.
Yield Strength: 130 ksi minimum.
Elongation: 14% minimum.
Reduction of Area: 40% minimum.
Hardness: Rockwell C33–38.
Sizes: Available in diameters from 1/2" to 1-1/2".
Types and Classifications
ASTM A490 bolts are categorized into the following types:
Type 1
Material: Medium carbon alloy steel.
Applications: General structural connections.
Type 3
Material: Weathering steel.
Applications: Structures exposed to atmospheric conditions where enhanced corrosion resistance is beneficial.
Notes: Develops a protective rust layer, reducing the need for painting.
Note: Type 2 was withdrawn in 2002.
Common Applications
Bridges: Steel-to-steel connections in bridge construction.
Buildings: Structural frameworks requiring high-strength bolts.
Industrial Facilities: Heavy machinery and equipment assemblies.
Infrastructure Projects: Highways, railways, and other critical structures.
Benefits of Using ASTM A490 Bolts
High Strength: Suitable for applications requiring superior tensile strength.
Durability: Resistant to wear and environmental factors.
Standardization: Ensures compatibility and reliability across projects.
Versatility: Available in various types to suit different environmental conditions and structural requirements.
How to Select the Right ASTM A490 Type
Assess Environmental Conditions: Determine if corrosion resistance is needed (Type 3 for weathering steel).
Determine Load Requirements: Choose the appropriate bolt diameter and length based on structural loads.
Threading Needs: Decide between standard or fully threaded bolts based on the application.
Consult Standards: Refer to ASTM specifications and industry guidelines for specific applications.
ASTM A490 Compared to Other Standards
ASTM A325: Lower strength structural bolts with configuration restrictions.
ASTM A354 Grade BD: Similar mechanical properties, but allows for different configurations and sizes.
ASTM F3125: The current standard consolidates A490 and other specifications for structural bolts.
Frequently Asked Questions
Q1: Can ASTM A490 bolts be galvanized?
No, ASTM A490 bolts should not be hot-dip galvanized due to the risk of hydrogen embrittlement. However, they can be coated with zinc/aluminum corrosion protective coatings per ASTM F1136 Grade 3, commonly known as Geomet.
Q2: What is the difference between ASTM A490 and A325 bolts?
ASTM A490 bolts are made from alloy steel and have higher tensile strength compared to ASTM A325 bolts, which are made from medium carbon steel. A490 bolts are suitable for applications requiring higher strength.
Q3: Are there metric equivalents to ASTM A490 bolts?
Yes, ASTM A490M specifies the metric equivalents of A490 bolts, covering sizes M12 to M36.
Q4: What nuts and washers are compatible with ASTM A490 bolts?
For Type 1 bolts, use ASTM A563 Grade DH nuts and F436 Type 1 washers. For Type 3 bolts, use ASTM A563 Grade DH3 nuts and F436 Type 3 washers.
Strengthen Your Structures with ASTM A490 Bolts
ASTM A490 bolts offer high-strength solutions for critical structural applications. Understanding their properties, types, and appropriate usage ensures the selection of the right fasteners for your projects. For expert guidance and a comprehensive selection of ASTM A490 bolts, contact California Fastener today.
