Specification Overview
ASTM A322 is a standard specification published by ASTM International that covers a broad range of hot-wrought alloy steel bars intended for mechanical and structural applications. This specification includes steels like 4130 (and 4340 steel, amongst others), which are chromium-molybdenum (Cr-Mo) low alloy steels known for their strength, toughness, and versatility.
This specification covers hot-wrought alloy steel bars. Bar applications include forging, heat treating, cold drawing, machining and many structural components. The steel shall be made by one or more of the following primary processes: open-hearth, basic-oxygen, or electric-furnace. The primary melting may incorporate separate degassing or refining and may be followed by secondary melting using electro-slag remelting or vacuum arc remelting.
Within the limits of good manufacturing and inspection practices, the bars shall be free of injurious seams, laps, segregation, or other imperfections which, due to their nature, degree, and/or extent, will interfere with the use of the material in machining or fabrication of suitable parts.
Available Product Forms
All product forms are supplied as Hot-Wrought per ASTM A322 requirements. Custom sizes, lengths, and pre-machined forms are available upon request. Contact our materials specialists for non-standard dimensions.
Chemical Composition – 4130 Alloy Steel (ASTM A322)
| Element |
Symbol |
Range % |
Notes |
| Carbon |
C |
0.28–0.33% |
Controls strength and hardness |
| Manganese |
Mn |
0.40–0.60% |
Deoxidizer and strengthener |
| Chromium |
Cr |
0.80–1.10% |
Hardenability and corrosion resistance |
| Molybdenum |
Mo |
0.15–0.25% |
High-temperature strength and hardenability |
| Iron |
Fe |
Balance |
Base metal |
Chemical composition ranges are per ASTM A322 for 4130 alloy steel. Consult the current issue of ASTM A322 for precise minimum/maximum requirements. Aero-Vac provides full mill test reports (MTRs) with certified chemistry for every order.
Key Properties & Specification Details
| Property / Attribute |
Details |
| Specification Number |
ASTM A322 |
| Issuing Organization |
ASTM International |
| Material Type |
Hot-Wrought Alloy Steel Bars |
| Steel Grade |
4130 (UNS G41300) |
| Nominal Composition |
0.95Cr – 0.20Mo |
| Condition |
Hot-Wrought |
| Available Forms |
Steel Bars (round, flat, hex) |
| Strength-to-Weight Ratio |
Excellent – high strength with relatively low weight |
| Weldability |
Good – suitable for welded assemblies with proper pre/post-weld procedures |
| Toughness |
Excellent – resists impact and fatigue under high-stress conditions |
| Machinability |
Good – well suited for machining, cold drawing, and forging |
| Certification Available |
AS9100D / ISO 9001, Certificate of Conformance, MTR |
Typical Applications
Aerospace Components: Due to its high strength-to-weight ratio and excellent toughness, 4130 alloy steel is widely utilized in the aerospace industry. It is used to manufacture aircraft parts such as gears, bolts, and other high-stress components that require both lightness and strength.
Automotive Parts: In the automotive industry, 4130 (ASTM A322) alloy steel is used for a range of components including axles, gears, and other critical parts that require high strength and durability. Its resistance to wear and tear under high-stress conditions makes it a preferred choice for high-performance automotive applications.
Cycling Frame Construction: In the bicycle manufacturing industry, 4130 alloy steel finds its application in the construction of high-quality frames. The steel's high tensile strength and weldability allow for durable and lightweight bicycle frames that can withstand rough use while providing a comfortable ride.
Structural Applications: 4130 (ASTM A322) alloy steel can be used in a variety of structural applications including bridges, buildings, and even roller coasters. Its strength and versatility make it a popular choice for architects and engineers looking to balance safety and efficiency in their designs.
Industrial & Mechanical Applications: Pump shafts, valve bodies, tooling components, and fittings requiring high strength, good machinability, and resistance to wear and fatigue under demanding operating conditions.
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