ThePipingMart Blog Grades AISI 8645 Alloy Steel (UNS G86450) – Composition, Uses and Properties

AISI 8645 Alloy Steel (UNS G86450) – Composition, Uses and Properties

AISI 8645 Steel

AISI 8645 steel is a high-strength alloy steel that has been used in many industries for decades. Its strength and toughness make it ideal for automotive components, heavy machinery, power tools, and industrial equipment applications. Let’s explore the various uses of AISI 8645 steel and how its unique properties can help you get the job done.

AISI 8645 Chemical Composition

Element Content (%)
Iron, Fe 96.595 – 97.72
Manganese, Mn 0.75 – 1
Carbon, C 0.43 – 0.48
Nickel, Ni 0.40 – 0.70
Chromium, Cr 0.40 – 0.60
Silicon, Si 0.15 – 0.30
Molybdenum, Mo 0.15 – 0.25
Sulfur, S ≤0.040
Phosphorous, P ≤0.035

AISI 8645 Physical Properties

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

AISI 8645 Mechanical Properties

Properties Metric Imperial
Tensile strength 1158 MPa 167953 psi
Yield strength 1034 MPa 149969 psi
Elongation 15% 15%
Bulk modulus 140 GPa 20300 ksi
Shear modulus 80 GPa 11600 ksi
Hardness, Brinell 184 – 235 184 – 235
Hardness, Vickers 220 220
Hardness, Knoop 239 239

AISI 8645 Thermal Properties

Properties Metric Imperial
Thermal expansion co-efficient (@0-100°C/32-212°F) 16-17 µm/m°C 8.8-9.4 µin/in°F
Thermal conductivity 16 W/mK 110.94².°F

AISI 8645 Equivalent

  • SAE J404
  • SAE J412
  • SAE J770
  • ASTM A322
  • ASTM A331
  • ASTM A505
  • ASTM A519
  • MIL-SPEC MIL-S-16974

AISI 8645 Uses

AISI 8645 steel is known for its strength and durability. It is often used in the construction of parts such as automotive components, heavy machinery, power tools, and industrial equipment. Additionally, it can be machined into shapes that are used in a variety of mechanical applications. Its strength also makes it suitable for applications requiring high wear resistance.

Corrosion Resistance

AISI 8645 steel offers excellent corrosion resistance due to its chromium content. The chromium creates a thin oxide film on the surface of the metal that prevents further oxidation from occurring. This makes it ideal for parts exposed to salt water or other harsh environments where corrosion could occur over time.

Heat Resistance

AISI 8645 steel also has excellent heat resistance properties due to its high melting point. This allows it to withstand temperatures up to approximately 1200°C before it begins to weaken or lose its strength. This makes AISI 8645 an ideal choice for applications where exposure to extreme heat could occur over time.

Heat Treatment

For added strength and toughness, AISI 8645 can be heat treated using several different methods depending on the desired result. Heat treating can improve wear resistance and increase overall strength by increasing the hardness of the material without sacrificing ductility or toughness. Additionally, heat treatment can reduce internal stress, which improves dimensional stability and reduces potential warping or distortion during machining operations.


Machining with AISI 8645 requires precise cutting tools with sharp edges as well as lubricants designed specifically for use with this type of metal alloy material. High-speed cutting tools should be avoided when working with this material due to their tendency to work harden quickly, which increases tool wear significantly if not properly managed during operation. Additionally, cutting speeds should be kept low when machining large sections of material, as this will reduce work hardening while still allowing sufficient stock removal rates for most operations.


AISI 8645 steel is an excellent choice for many applications thanks to its impressive combination of strength, corrosion resistance, heat resistance, and machinability properties; all rolled into one package! Whether you’re designing something new or repairing something old, knowing about all these features can help ensure your project runs smoothly from start to finish! If you need help selecting a suitable alloy grade or have any other questions about working with metals like AISI8645, please don’t hesitate to contact us today! We would love nothing more than helping out our fellow engineers create great products!

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