ASTM A618 Hot-Formed High-Strength Low-Alloy Structural Tubing
ASTM A618 is the industry standard for hot-formed, high-strength, low-alloy structural tubing. This material is widely used in various construction and industrial applications where superior strength, durability, and corrosion resistance are required. Manufactured using a specialized hot-forming process, ASTM A618 tubing exhibits enhanced mechanical properties compared to standard carbon steel, making it an excellent choice for load-bearing structural components, machinery frames, heavy equipment, and other demanding applications. Offering a range of strength grades and dimensional options, ASTM A618 tubing provides engineers and fabricators with a versatile, high-performance material that can be tailored to meet the unique requirements of each project. Whether specifying for new construction or retrofitting existing structures, ASTM A618 delivers the strength, reliability, and cost-effectiveness that modern industry demands.

Chemical Composition of ASTM A618 Hot-Formed High-Strength Low-Alloy Structural Tubing

ASTM A618 Tensile Requirements
	Grades la, lb, and ll				Grade lll
	Walls 3⁄4 in. [19.05 mm] and Under		Walls over 3⁄4 to 1 1⁄2 in. [19.05 to 38.1mm], incl


Tensile strength, min, ksi [MPa]A	70	[485]	67	[460]	65	[450]
Yield strength, min, ksi [MPa]A	50	[345]	46	[315]	50	[345]
Elongation in 2 in. or 50 mm, min, %	22		22		20
Elongation in 8 in. or 200 mm, min, %	19		18		18
A For Grade II, when the material is normalized, the minimum yield strength and minimum tensile strength required shall be reduced by 5 ksi [35 MPa]

ASTM A618 Chemical Requirements
Composition, %	Grade Ia		Grade Ib		Grade II		Grade III
Composition, %	Heat	Product	Heat	Product	Heat	Product	Heat	Product
Carbon, max	0.15	0.18	0.2	. . .	0.22	0.26	0.23A	0.27A
Manganese	1.00 max	1.04 max	1.35 max	1.40 max	0.85–1.25	1.30 max	1.35 maxA	1.40 maxA
Phosphorus	0.07–0.15	0.07–0.16	0.025 max	0.035 max	0.025 max	0.035 max	0.025 max	0.035 max
Sulfur, max	0.025	0.045	0.025	0.035	0.025	0.035	0.025	0.035
Silicon, max	. . .	. . .	. . .	. . .	0.3	0.33	0.3	0.35
Copper, min	0.2	0.18	0.20B	0.18B	0.2	0.18	. . .	. . .
Vanadium, min	. . .	. . .	. . .	. . .	0.02	0.01	0.02C	0.01
A For each reduction of 0.01 % C below the specified carbon maximum, an increase of 0.05 % manganese above the specified maximum will be permitted up to 1.45 % for the heat analysis and up to 1.50 % for the product analysis.
B If chromium and silicon contents are each 0.50 % min, then the copper minimums do not apply.
C For Grade III, columbium may be used in conformance with the following limits: 0.005 %, min (heat) and 0.004 %, min (product).

Specifications
Standard ASTM A618 Hot-Formed High-Strength Low-Alloy Structural Tubing
Steel Grade/Material Gr.Ia, Gr.Ib, Gr.II. Gr.III
Round Tubing DN15-DN600, NPS 1/2″ – 24″ (21.3-609.6mm) x WT: 0.109″ – 1.000″ (2.8 – 25.4mm)
Square Tubing 20 x 20 – 1200 x 1200mm x WT: 2.8 – 60mm
Rectangular Tubing 20 x 30 – 1000 x 1200mm x WT: 2.8 – 60mm
Length 1 – 12m
Packing Plain/Beveled Ends, Loosely Packed
Surface Treatment Bare, Black and Hot-dipped Galvanized
Section Shape Round, Square, Rectangular
Technique Seamless or Welded
Place of Origin Made in China
MOQ 25 Tons
Transportation Railway, By Sea
Applications
Construction and Infrastructure
Bridges: ASTM A618 tubing is commonly used to fabricate bridge components, especially in areas where high-strength structural tubing is required to support heavy loads and resist environmental degradation.

Buildings: It is utilized to construct steel frames, columns, beams, and other structural supports where high strength-to-weight ratios are essential. This is especially beneficial in high-rise buildings and industrial structures.

Transmission Towers: Due to its strength and resistance to fatigue, ASTM A618 is used in constructing electrical transmission towers and other large infrastructure projects requiring durable structural components.

Automotive Industry
Chassis and Frames: In automotive manufacturing, ASTM A618 is used for chassis components and frame rails that require high strength and impact resistance. It is often used to produce light trucks, buses, and off-road vehicles.

Safety Structures: The tubing is also used in safety-critical automotive components such as roll cages and impact beams, where high-strength materials are necessary to protect occupants in the event of an accident.

Agricultural Equipment
Tractors and Machinery: The tubing's high tensile strength makes it ideal for use in agricultural equipment such as tractors, plows, and other heavy-duty machinery that endure substantial mechanical stress and require durability.

Harvesters and Loaders: Similar to tractors, harvesters and loaders benefit from ASTM A618 tubing because it can withstand vibration, shock loads, and wear during operation in challenging environments.

Heavy Equipment Manufacturing
Construction Equipment: Excavators, bulldozers, and cranes are manufactured using ASTM A618 because it can support large loads and resist fatigue and wear, which is crucial for heavy equipment working in demanding environments.

Forklifts and Material Handling: The tubing is also used to manufacture forklift frames, lift masts, and other material handling machinery, where strength and resilience are critical for safe operation.

Energy and Oil & Gas Industry
Pipeline Supports and Brackets: In the oil and gas industry, ASTM A618 is used to construct supports, brackets, and other structural components for pipelines. Its strength and resistance to corrosion and fatigue make it ideal for harsh operating environments.

Wind Turbine Structures: This material is used to construct the framework of wind turbines, where structural integrity under stress and resistance to wind and weather conditions are essential.

Railroad Industry
Railcar Components: ASTM A618 is used to manufacture structural components for railcars, such as underframes and other critical structural elements. These components must withstand high loads, vibrations, and significant mechanical stresses.

Railroad Bridges: The tubing is also used in railroad bridges, where its high strength and low-alloy composition offer resistance to wear and fatigue, especially in regions with varying weather and environmental conditions.

Marine and Offshore Applications
Shipbuilding: ASTM A618 is used to construct structural tubing for ships and offshore platforms. Its ability to resist corrosion, fatigue, and impact from harsh marine environments makes it suitable for various marine applications.

Oil Rigs: The tubing is also used for structural elements in oil rigs and offshore drilling platforms, where high strength is necessary to support large, heavy equipment in challenging offshore environments.

Structural Components for Industrial Machinery
Cranes and Hoists: The material is used to construct industrial cranes and hoisting equipment, where strength and fatigue resistance are essential for handling heavy loads over long periods.

Conveyor Systems: In the manufacturing and mining industries, ASTM A618 tubing is used for conveyor frames, rollers, and other structural elements that need to support heavy, moving loads.

Sports Equipment
Bicycle Frames: Some high-end bicycle frames, especially for competitive sports, use ASTM A618 tubing because of its strength-to-weight ratio. The material helps achieve the desired performance while maintaining durability and safety.

Outdoor and Adventure Equipment: Other sports and adventure equipment, such as trekking poles, camping gear frames, and lightweight structural components, can also benefit from ASTM A618's combination of strength and lightweight properties.

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