ThePipingMart Blog Grades AISI 8640 Alloy Steel (UNS G86400) – Properties Uses and Composition

AISI 8640 Alloy Steel (UNS G86400) – Properties Uses and Composition

AISI 8640 Steel

AISI 8640 steel is a versatile medium-carbon nickel-chromium-molybdenum alloy steel that has proven its worth as a reliable metal in countless industrial applications. Its properties make it suitable for a wide range of uses, including automotive components, shafts, and gears. AISI 8640 Alloy Steel, also known as SAE-AISI 8640 steel, is a low-alloy steel that is primarily used in machinery and equipment manufacturing. This steel is composed of carbon, manganese, silicon, chromium, nickel, and molybdenum. The unique composition of AISI 8640 Alloy Steel provides it with superior strength, toughness, and wear resistance. The steel can be easily heat-treated to improve its properties, making it an excellent choice for applications that require high strength and durability. Its low carbon content makes it easily weldable without any risk of cracking. Overall, AISI 8640 Alloy Steel, also known by its UNS G86400 designation, is an excellent choice for applications requiring strength, durability, and weldability.

What Forms of AISI 8640 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 8640 Chemical Composition

Element Content (%)
Manganese, Mn 0.75-1.00
Nickel, Ni 0.40-0.70
Chromium, Cr 0.40-0.60
Carbon, C 0.38-0.43
Silicon, Si 0.15-0.30
Molybdenum, Mo 0.15-0.25
Sulfur, S 0.04 (max)
Phosphorus, P 0.035 (max)

AISI 8640 Physical Properties

Properties Metric Imperial
Density 7.7-8.03 g/cm3 0.278-0.290 lb/in3

AISI 8640 Mechanical Properties

Properties Metric Imperial
Elastic modulus 190-210 GPa 27557-30458 ksi
Poisson’s ratio 0.27-0.30 0.27-0.30

AISI 8640 Equivalent

DIN 1.6546 UNI 40 NiCrMo 2 KB B.S. Type 7 ASTM A322 ASTM A331
ASTM A506 ASTM A519 SAE J404 SAE J412 SAE J770

AISI 8640 Uses

8640 Alloy Steel is typically used in applications such as crankshafts, couplings, and other automotive parts; shafts for machinery; and gears. It is also used in oil refineries and petrochemical plants due to its excellent corrosion resistance. Additionally, it can be used for various components in aircraft construction, such as landing gear frames, supports for engines and transmissions, cowlings, propeller shafts, and more.

AISI 8640 Uses in Industries

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

AISI 8640 Corrosion Resistance

One reason why this type of steel is so widely used is its high level of corrosion resistance. This is because it contains chromium which helps protect against oxidation and rusting from water or air exposure. Additionally, molybdenum increases the overall resistance to corrosion because it forms an oxide film on the surface that acts as a barrier between the metal and any corrosive elements. This makes it an ideal choice for use in environments where high levels of humidity are present or when there is continuous contact with water or other liquids.

AISI 8640 Heat Resistance & Heat Treatment

AISI 8640 steel also offers good heat resistance due to the presence of nickel and chromium. These two elements combine to create an alloy that can withstand temperatures up to 1200°F (650°C). Heat treatment can be used to further strengthen this type of steel by increasing hardness as well as improving wear resistance and fatigue strength. However, care must be taken not to overheat the material during heat treatment as this could lead to cracking or distortion of the material’s shape or structure.

AISI 8640 Machining

Machining AISI 8640 steel requires special attention due to its hardening behaviour during machining operations. It should only be machined with tools designed specifically for hard materials, such as carbide-tipped tools with positive rake angles (generally 10 degrees) and slow cutting speeds (around 50 feet per minute). Additionally, coolants should always be used when machining this type of steel to help reduce friction between the tool and workpiece while also preventing heat buildup, which can lead to distortion or cracking if not properly controlled.


AISI 8640 steel has repeatedly proven itself in numerous industrial applications thanks to its combination of corrosion resistance, heat resistance, machinability, strength, ductility and durability under a wide range of working conditions. From automotive components like crankshafts and gears through aircraft components like supports for engines and transmissions – there really isn’t much this versatile medium-carbon nickel-chromium-molybdenum alloy cannot do! So if you’re looking for an all-purpose metal that will provide long-lasting performance no matter what environment you may find yourself working in, look no further than AISI 8640!

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