Understanding ASTM A871 Grade 65 and ASTM A709 Grade 36: High-Strength Low-Alloy Steels

October 7, 2023 - 0 COMMENTS



Steel is a crucial material in construction and engineering due to its strength, durability, and versatility. Two popular types of high-strength low-alloy (HSLA) steels used in various structural applications are ASTM A871 Grade 65 and ASTM A709 Grade 36. In this blog, we will delve into the characteristics, applications, and differences between these two steel grades to help you make informed decisions in your projects.

ASTM A871 Grade 65

ASTM A871 Grade 65 is a high-strength low-alloy structural steel that finds applications in bridges, buildings, and other structural elements exposed to atmospheric conditions. This steel grade is known for its exceptional corrosion resistance, which makes it suitable for outdoor and marine environments. Some key characteristics of ASTM A871 Grade 65 include:

Corrosion Resistance: ASTM A871 Grade 65 is designed to resist atmospheric corrosion, making it an excellent choice for structures in coastal regions or areas with high humidity.

High Strength: It possesses a minimum yield strength of 65,000 psi (450 MPa), which ensures structural integrity and load-bearing capacity.

Weldability: This steel grade is weldable using various welding processes, which allows for flexibility in construction and repair.

Weathering Properties: ASTM A871 Grade 65 develops a protective oxide layer over time, enhancing its resistance to corrosion and reducing the need for maintenance.

Applications of ASTM A871 Grade 65:

Bridge construction in corrosive environments.
Transmission and telecommunications towers.
Architectural components, such as facades and roofing.
Railway and highway structures.
ASTM A709 Grade 36

ASTM A709 Grade 36 is another HSLA steel known for its high-strength properties and versatility. This grade is primarily used in the construction of bridges and other structural components. Key features of ASTM A709 Grade 36 include:

High Strength: It has a minimum yield strength of 36,000 psi (250 MPa), making it suitable for various structural applications.

Ductility: ASTM A709 Grade 36 offers good ductility, which is essential for withstanding dynamic loads and seismic activity.

Formability: This steel grade is easily formable, allowing for the creation of complex shapes and designs.

Weldability: ASTM A709 Grade 36 can be welded using common welding techniques, making it a preferred choice for construction projects.

Applications of ASTM A709 Grade 36:

Bridge construction, including highway and pedestrian bridges.
Building structures, such as columns, beams, and support elements.
Offshore platforms.
Transmission towers.
Key Differences between ASTM A871 Grade 65 and ASTM A709 Grade 36

Corrosion Resistance: The most significant difference is in their corrosion resistance. ASTM A871 Grade 65 is specifically designed for outdoor and corrosive environments, whereas ASTM A709 Grade 36 is more suited for standard structural applications.

Yield Strength: ASTM A871 Grade 65 has a higher minimum yield strength of 65,000 psi compared to ASTM A709 Grade 36, which has a minimum yield strength of 36,000 psi.

Applications: While both grades are used in structural applications, ASTM A871 Grade 65 is preferred for projects in aggressive atmospheric conditions, while ASTM A709 Grade 36 is suitable for standard structural projects.


ASTM A871 Grade 65 and ASTM A709 Grade 36 are two high-strength low-alloy steels that serve different purposes in the construction and engineering industries. ASTM A871 Grade 65 excels in corrosive environments, providing excellent corrosion resistance, while ASTM A709 Grade 36 is a versatile choice for various structural applications with its good strength and formability. Understanding the unique characteristics of each steel grade is essential in selecting the right material for your specific project requirements.


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