ThePipingMart Blog Grades AISI 4027 Alloy Steel (UNS G40270) – Composition, Properties and Uses

AISI 4027 Alloy Steel (UNS G40270) – Composition, Properties and Uses

AISI 4027 Steel

AISI 4027 is a high-carbon, low-alloy steel that is typically used in the production of automotive parts and components. 4027 Alloy Steel is widely appreciated for its strength, durability, and corrosion resistance. AISI 4027 alloy steel, also known as UNS G40270, is a high-quality steel that possesses excellent mechanical properties. This alloy steel is commonly used in applications that require high strength, toughness, and good wear resistance. AISI 4027 steel is mainly composed of elements such as carbon, manganese, chromium, and molybdenum. These elements work together to promote the steel’s strength and durability, making it ideal for use in various industries such as construction, manufacturing, and engineering. SAE-AISI 4027 steel is heat treatable, which means it can be hardened and tempered for optimal performance and longevity. Its unique composition ensures that it is resistant to wear and tear, making it an excellent choice for parts and components that need to withstand friction and stress. With its exceptional properties and versatility, AISI 4027 alloy steel is a reliable choice for many different applications. In this article, we will discuss the key features of UNS G40270 steel as well as how it can be treated and machined to suit your needs.

What Forms of AISI 4027 is Available at Piping Mart?

  • Nut
  • Bar
  • Bolt
  • Pipe
  • Screw
  • Tubing
  • Valves
  • Washers
  • Flanges
  • Fasteners
  • Electrodes
  • Stud Bolts
  • Sheet Plates
  • Pipe Fittings
  • Forged Fitting
  • Instrumentation Fittings

AISI 4027 Composition

Element Content (%)
Iron, Fe 98.08-98.7
Manganese, Mn 0.70-0.90
Carbon, C 0.25-0.30
Molybdenum, Mo 0.20-0.30
Silicon, Si 0.15-0.35
Sulfur, S 0.040
Phosphorous, P 0.035

AISI 4027 Physical Properties

Properties Metric Imperial
Density 7.85 g/cm3 0.284 lb/in³

AISI 4027 Mechanical Properties

Properties Metric Imperial
Tensile strength 515 MPa 74700 psi
Yield strength 325 MPa 47100 psi
Bulk modulus (typical for steel) 140 GPa 20300 ksi
Shear modulus (typical for steel) 80.0 GPa 11600 ksi
Elastic modulus 190-210 GPa 27557-30458 ksi
Poisson’s ratio 0.27-0.30 0.27-0.30
Elongation at break (in 50 mm) 30.00% 30.00%
Reduction of area 52.90% 52.90%
Hardness, Brinell 143 143
Hardness, Knoop (converted from Brinell hardness) 163 163
Hardness, Rockwell B (converted from Brinell hardness) 78 78
Hardness, Vickers (converted from Brinell hardness) 149 149
Machinability (annealed and cold drawn. Based on 100 machinability for AISI 1212 steel) 70 70

AISI 4027 Thermal Properties

Properties Metric Imperial
Thermal conductivity (typical steel) 44.5 W/mK 309 BTU in/hr.ft².°F

AISI 4027 Equivalent

  • ASTM A322
  • ASTM A331
  • ASTM A519
  • SAE J404
  • SAE J412
  • SAE J770

AISI 4027 Uses

AISI 4027 alloy steel is a versatile material widely used in various industrial applications. Due to its excellent strength, toughness, and wear resistance, it is commonly used in manufacturing gears, shafts, and other high-stress components. This steel is also often used in the production of automotive parts, such as axles and suspension components, as well as in construction equipment and drilling tools. Its ability to withstand high heat and pressure make it ideal for use in the oil and gas industry. In summary, AISI 4027 is a reliable and durable material that plays a vital role in many different industries.

AISI 4027 Uses in Industries

  • Automotive Industry
  • Aerospace Industry
  • Construction Industry
  • Oil and Gas Industry
  • Power Generation Industry
  • Manufacturing Industry

AISI 4027 Corrosion Resistance

AISI 4027 has good corrosion resistance when exposed to mild atmospheres, fresh water, steam, ammonia solutions, and other non-oxidizing media such as acetone and ethyl alcohol. The corrosion resistance of this steel type is also excellent when compared to other high-carbon steels.

AISI 4027 Heat Resistance

AISI 4027 has an impressive heat-resistant property that makes it suitable for use in applications that require high-temperature stability. This steel type can withstand temperatures up to 982°F without any significant loss of strength or performance. It also has excellent scaling resistance up to 1450°F, which makes it ideal for long-term heat exposure applications.

AISI 4027 Heat Treatment

The heat treatment process of AISI 4027 involves heating the material above its critical transformation point, followed by quenching in oil or air cooling, depending on the desired properties required from the final product. If higher strength and wear resistance are needed, then oil quenching should be preferred, while air cooling should be done if better ductility is desired from the part or component produced from this steel type. 

AISI 4027 Machining

When machining AISI 4027 steel, one must consider its higher carbon content, which will require heavier cuts during machining operations, in order for the material to not chip off or break due to the sudden impact caused by heavy cuts. Using proper lubricants and coolants during machining will result in smoother surface finishes desired from parts made with this type of steel. 


In conclusion, AISI 4027 is a versatile high-carbon, low-alloy steel that offers excellent corrosion resistance, heat resistance, scaling resistance and machinability, making it suitable for a wide range of applications across various industries such as automotive manufacturing and other related fields where these qualities are highly desired. With proper heat treatment processes such as oil quenching or air cooling, one can further enhance the already impressive properties of this material resulting in parts with higher strength and wear resistance as well as improved ductility depending on what’s required from them, ultimately leading to increased customer satisfaction for your products or services you offer using this amazing material!

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