ThePipingMart Blog Grades AISI 8740 Alloy Steel (UNS G87400) – Compositon, Properties and Uses

AISI 8740 Alloy Steel (UNS G87400) – Compositon, Properties and Uses

AISI 8740 Steel

AISI 8740 steel, a medium-carbon, low-alloy option, finds broad utility in diverse industries. Renowned for its corrosion and heat resistance, it’s easily machinable and heat treatable. This article delves into AISI 8740’s chemical makeup, applications, corrosion and heat resistance, machinability, and heat treatment. Recognized as UNS G87400 and SAE-AISI 8740, it’s a versatile alloy with carbon, manganese, phosphorus, sulfur, silicon, nickel, chromium, and molybdenum. These elements contribute to its exceptional strength, toughness, and hardness, maintaining a balanced profile ideal for critical applications like aircraft landing gear, gears, and shafts, establishing AISI 8740 Alloy Steel as indispensable in numerous industrial scenarios.

What Forms of AISI 8740 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 8740 Chemical Composition

AISI 8740 Alloy Steel is a medium-carbon alloy with a Nickel content (Ni) of 0.400-0.700%, Chromium (Cr) content of 0.400-0.600%, Manganese (Mn) content of 0.750-1.00%, Molybdenum (Mo) content of 0.200-0.300%, Phosphorus (P) content of 0.0350%, Sulfur (S) content of 0.0400%, Silicon (Si) content of 0.150-0.300%, and Carbon (C) content of 0.380-0.430%. UNS G87400 also contains trace amounts of other elements, such as Copper (Cu), Vanadium (V), Nitrogen (N), and Aluminium (Al).

Element Content (%)
Iron, Fe 96.595-97.72
Manganese, Mn 0.750-1.00
Nickel, Ni 0.400-0.700
Chromium, Cr 0.400-0.600
Carbon, C 0.380-0.430
Molybdenum, Mo 0.200-0.300
Silicon, Si 0.150-0.300
Sulfur, S 0.0400
Phosphorous, P 0.0350

AISI 8740 Physical Properties

AISI 8740 Alloy Steel exhibits a density of 7.85 to 7.87 grams per cubic centimeter (g/cm³). This measurement signifies the alloy’s mass per unit volume, offering valuable insights into its inherent physical attributes.

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

AISI 8740 Mechanical Properties

AISI 8740 Alloy Steel exhibits exceptional mechanical characteristics, attributed to its meticulously balanced combination of Carbon, Manganese, Phosphorus, Sulfur, Silicon, Nickel, Chromium, and Molybdenum. This unique composition leads to remarkable Strength, Toughness, and Hardness. The well-proportioned alloy is ideally suited for crucial applications such as aircraft landing gear, gears, and shafts, guaranteeing reliable performance across diverse industrial environments.

Properties Metric Imperial
Tensile strength 695 MPa 101000 psi
Yield strength 415 MPa 60200 psi
Elastic modulus 190-210 GPa 27557-30458 ksi
Bulk modulus (typical for steel) 140 GPa 20300 ksi
Shear modulus (typical for steel) 80 GPa 11600 ksi
Poisson’s ratio 0.27-0.30 0.27-0.30
Elongation at break (50mm) 22.20% 22.20%
Izod Impact 41 J 30.2
Hardness, Brinell 201 201
Hardness, Knoop (converted from Brinell hardness) 223 223
Hardness, Rockwell B (converted from Brinell hardness) 93 93
Hardness, Rockwell B (converted from Brinell hardness, value below normal HRC range, for comparison only) 13 13
Hardness, Vickers (converted from Brinell hardness) 211 211
Machinability (hot rolled and cold drawn, based on 100 machinability for AISI 1212 steel) 65 65

AISI 8740 Thermal Properties

Properties Metric Imperial
Thermal conductivity 46.6 W/mK 323 BTU in/hr.ft².°F

AISI 8740 Equivalent

AISI 8740 steel has equivalents in various international standards. By European standards, it corresponds to 34CrNiMo6 (1.6582). By British standards, it is comparable to 817M40 (EN24). These equivalents share similar chemical compositions and mechanical properties, ensuring application interchangeability. Consulting specific standards is advisable for precise equivalency and compatibility in diverse industrial contexts.

DIN 1.6546 UNI 40 NiCrMo 2 KB B.S. Type 7 AMS 6322 AMS 6322F AMS 6323
AMS 6323D AMS 6325 AMS 6325D AMS 6327D AMS 6358 AMS 6358B
ASTM A322 ASTM A331 ASTM A505 ASTM A519 SAE J770 SAE J412
AMS 6327 MIL SPEC MIL-S-6049 AMS 7496 ASTM A29 ASTM A752 MIL S-6049
SAE J1397 ASTM A320 (L7C, L73) SAE J404

AISI 8740 Uses

AISI 8740 steel has many uses in industries such as automotive, petrochemical processing plants, aerospace manufacturing companies, agriculture, construction equipment manufacturing companies, oil & gas exploration companies, etc., due to its excellent mechanical properties like good strength and toughness at elevated temperatures along with high wear resistance which makes it perfect for these types of applications where high-performance parts are required for long term use in harsh environments or extreme conditions.

AISI 8740 Uses in Industries

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

AISI 8740 Corrosion Resistance & Heat Resistance

Due to the presence of chromium in the alloy’s composition, AISI 8740 steel offers good corrosion resistance properties making it ideal for applications exposed to corrosive environments or chemicals like oils & gases, etc., Additionally due to its high carbon & manganese contents along with added nickel and molybdenum contents provide excellent wear resistance property even under extreme temperatures making it perfect for applications that require parts which need to withstand harsh environment or conditions without any major degradation over time or wear off quickly which makes it perfect for long term use in highly demanding industries like an automotive industry where engines operating at very high temperatures are expected to run efficiently over a long period without any major issue arising from material degradation due to exposure from extreme temperature changes during engine operating cycles.

AISI 8740 Machining & Heat Treatment Process

AISI 8740 steel can be easily machined using conventional methods as well as modern machining techniques like CNC turning or CNC milling etc. Additionally, it also can be easily welded using welding processes like MIG welding or TIG welding, etc., And lastly, it can also be subjected to heat treatment processes like annealing or normalizing, etc., depending on the type of application that requires specific properties from the final product made out using this grade material.


To sum up, AISI 8740 Steel is an excellent all-purpose medium-carbon low alloy steel that provides good strength and toughness at elevated temperatures and great wear resistance properties, making it perfect for applications requiring parts working under extreme conditions or harsh environments. Its unique combination of chemical composition along with ease in machining makes it an ideal choice for applications that require both quality & performance from their components over a long period, so if you are looking for a reliable material, then look no further than AISI 8740!

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