ThePipingMart Blog Grades SAE/AISI 1040 Carbon Steel (UNS G10400) – Composition, Properties and Uses

SAE/AISI 1040 Carbon Steel (UNS G10400) – Composition, Properties and Uses

SAE / AISI 1040 Steel

AISI 1040 steel is medium carbon steel with good hardness and strength. It is also ductile and easily machined. 1040 Carbon Steel can be heat treated for higher hardness. The composition of this steel makes it suitable for many different applications, such as gears, shafts, axles, and other engineering uses. Let’s take a closer look at the composition and properties of UNS G10400 steel.

AISI 1040 Composition

SAE / AISI 1040 steel consists of carbon, manganese, silicon, phosphorus, sulfur, and trace amounts of other elements. Carbon is the main alloying element present in this steel. Manganese and silicon are present in smaller quantities. The carbon content in this steel is between 0.37-0.44%

Element Content (%)
Iron, Fe 98.6-99
Manganese, Mn 0.60-0.90
Carbon, C 0.370-0.440
Sulfur, S ≤ 0.050
Phosphorous, P ≤ 0.040

AISI 1040 Physical Properties

Properties Metric Imperial
Density (chemical composition of 0.435% C, 0.69% Mn, 0.20% Si, annealed at 860°C (1580°F)) 7.845 g/cc 0.2834 lb/in³
Melting point 1521°C 2770°C

AISI 1040 Mechanical Properties

Properties Metric Imperial
Tensile strength 620 MPa 89900 psi
Yield strength 415 MPa 60200 psi
Bulk modulus (typical for steels) 140 GPa 20300 ksi
Shear modulus (typical for steels) 80 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) 25% 25%
Reduction of area 50% 50%
Hardness, Brinell 201 201
Hardness, Knoop (converted from Brinell hardness) 223 223
Hardness, Rockwell B (converted from Brinell hardness) 93 93
Hardness, Rockwell C (converted from Brinell hardness. Value below normal HRC range, for comparison purposes only) 13 13
Hardness, Vickers (converted from Brinell hardness) 211 211
Izod impact (annealed at 790°C (1450°F)) 45 J 33.2 ft-lb
Izod impact (as rolled) 49 J 36.1 ft-lb
Izod impact (normalized at 900°C (1650°F) 65 J 47.9 ft-lb

AISI 1040 Thermal Properties

Properties Metric Imperial
Thermal expansion co-efficient (@ 20-100°C/68-212°F, composition of 0.40% C, 0.11% Mn, 0.01% P, 0.03% S, 0.03% Si, 0.03% Cu) 11.3 µm/m°C 6.28 µin/in°F
Thermal conductivity (@ 100°C/212°F) 50.7 W/mK 352 BTU in/hr.ft².°F
Thermal conductivity (@ 0°C) 51.9 W/mK 360 BTU in/hr.ft².°F

AISI 1040 Equivalent

  • ASTM A29 (1040)
  • ASTM A510 (1040)
  • ASTM A513
  • ASTM A519 (1040)
  • ASTM A546 (1040)
  • ASTM A576 (1040)
  • ASTM A682 (1040)
  • ASTM A827
  • ASTM A830
  • MIL S-11310 (CS 1040)
  • MIL S-16788
  • MIL S-46070
  • SAE J1397 (1040)
  • SAE J403 (1040)
  • SAE J412 (1040)

AISI 1040 Uses

This steel can be used in a variety of applications, such as gears, shafts, axles, engineering parts, and other miscellaneous uses. Its high strength and good machinability make it a popular choice for many different applications. This steel can be heat treated for higher hardness levels if required by the application.

Corrosion Resistance

The SAE/AISI 1040 steel alloy offers many benefits with its corrosion resistance properties. It provides maximum resistance in atmospheres with high humidity, preventing rust and pitting of the material surface. Additionally, it is resistant to most corrosive agents, such as acidic solutions, alkaline solutions and salt sprays. With its superior ability to resist chemicals and humid environments, this alloy makes an excellent choice for a variety of applications, including high-temperature and cryogenic storage tanks, farm equipment, ships, bridges and naval applications. Its performance has been proven in many extreme conditions with no significant loss or detriment to the material structure. Due to these remarkable qualities and versatile usage possibilities, SAE/AISI 1040 has become one of the most trusted alloys in industrial settings around the world.

Heat Resistance

The heat resistance of SAE / AISI 1040 steel is remarkable, making it a favourite choice for use in extreme temperatures. It is well-suited to applications demanding excellent mechanical strength and toughness at both room temperature and in high-temperature environments. With a capacity to resist scaling and oxidation at temperatures up to 800°C, this versatile steel has been seen used in a variety of engineering scenarios where heat retention might be an issue. Furthermore, its tenacity remains satisfactory even when the steel is subjected to temperatures exceeding 1,000°C, making it a reliable option for durable results through countless heating cycles.

Heat Treatment

Heat treatment of SAE / AISI 1040 is generally carried out by hardening and tempering the steel. This is done by heating the steel to a high temperature, cooling it quickly and then reheating it at a lower temperature for a period of time. Depending on the desired hardness, cooling can be done in oil or water, with the former usually preferred for greater toughness and strength. While tempering can increase ductility and wear resistance, proper heat treatment of SAE / AISI 1040 requires precision timing and exact temperatures to achieve consistent results across multiple pieces of material. Through proper heat treatment, SAE / AISI 1040 can become an incredibly useful tool for applications that require superior strength and durability.


The machinability of AISI 1040 steel is pretty good. It can be machined using all the conventional methods like turning, drilling, tapping, etc. This steel can be hardened by heating it to 870-900C. Quenching is done in air or oil. Tempering is done at 460-520C for better Honing, grinding and surface finish results. This alloy does not exhibit temper brittleness.


SAE/AISI 1040 welding provides excellent structural integrity with superior tensile strength and ductility. It offers good machinability due to its carbon content as well as weldability because of both low carbon and medium-low alloy content. It can also be carburized or hardened by cold working. 1040 is an ideal choice for parts that require tremendous amounts of stress or weight, such as drive shafts and connecting rods, while its ability to be easily fabricated makes it suitable for parts like gears, basic hand tools, and heavy-duty crankshafts in a variety of industries.


SAE / AISI 1040 is a versatile medium carbon steel with good hardness and strength levels. It is also easily machined and ductile. This steel can be used in many different applications, such as gears, shafts, axles, engineering parts, etc. It can also be heat treated for higher hardness levels if required by the application. Thanks for reading!

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SAE/AISI 1040 Carbon Steel (UNS G10400) – Composition, Properties and Uses

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