ThePipingMart Blog Grades AISI 4137 Alloy Steel (UNS G41370) – Composition, Properties and Uses

AISI 4137 Alloy Steel (UNS G41370) – Composition, Properties and Uses

AISI 4137 Steel

AISI 4137 steel is a low-alloy, chromium-molybdenum steel that exhibits good strength and toughness. UNS G41370 has excellent hardenability, and its machinability and weldability are also good. This versatile material is used in a variety of industries and applications, including automotive engineering, oil and gas exploration, agricultural machinery, machine tools, and general engineering. AISI 4137 Alloy Steel (UNS G41370) is a type of steel known for its strength and toughness. It is a SAE-AISI 4137 steel family member and comprises carbon, manganese, chromium, and molybdenum. With high durability and resistance to wear and tear, this steel is used in various applications, including machinery parts, aerospace components, and military equipment. Its impressive properties make it an excellent choice for harsh environments and high-stress applications. Overall, AISI 4137 Steel is a formidable material that can withstand the toughest conditions.

What Forms of AISI 4137 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 4137 Composition

Element Content (%)
Iron, Fe 96.93-97.85
Chromium, Cr 0.80-1.10
Manganese, Mn 0.70-0.90
Carbon, C 0.35-0.40
Silicon, Si 0.15-0.35
Molybdenum, Mo 0.15-0.25
Sulfur, S ≤ 0.040
Phosphorous, P ≤ 0.035

AISI 4137 Physical Properties

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

AISI 4137 Mechanical Properties

Properties Metric Imperial
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
Hardness, Brinell (annealed and cold drawn) 187-229 187-229
Hardness, Knoop (converted from Brinell hardness) 230 230
Hardness, Rockwell B (converted from Brinell hardness) 94 94
Hardness, Rockwell C (converted from Brinell hardness, value below normal HRC range, for comparison purposes only) 15 15
Hardness, Vickers (converted from Brinell hardness) 218 218
Machinability (based on 100 machinability for AISI 1212 steel) 70 70

AISI 4137 Thermal Properties

Properties Metric Imperial
Thermal conductivity 42.7 W/mK 296 BTU in/hr.ft².°F
Thermal expansion co-efficient (@0-100°C/32-212°F) 11.2 µm/m°C 6.22 µin/in°F

AISI 4137 Equivalents

AFNOR 40 CD 4 AFNOR 42 CD 4 DIN 1.7225 UNI 38 CrMo 4 KB UNI 40 CrMo 4 UNI G 4O CrMo 4
JIS SCM 4 JIS SCM 4 H SS 2244 B.S. 708 A 42 B.S. 708 M 40 B.S. 709 M 40
ASTM A322 ASTM A331 ASTM A505 ASTM A519 ASTM A547 SAE J404
SAE J412 SAE J770

AISI 4137 Uses

AISI 4137 is a type of alloy steel that is highly versatile and used in various applications. Its composition includes chromium, molybdenum, and nickel, which provide strength and durability. This steel is commonly used in the automotive and aerospace industries for components like gears, shafts, and bolts. It is also used in manufacturing machinery, industrial equipment, and oil drilling equipment due to its high resistance to wear and tear.

AISI 4137 Uses in Industries

Automotive Industry

One of the major uses of AISI 4137 steel is in the automotive industry. This type of steel is commonly used to make critical parts such as gears, shafts, and axles due to its high strength and wear resistance. It is also used in suspension and engine parts requiring high toughness and fatigue resistance.

Oil and Gas Industry

AISI 4137 steel is widely used in the oil and gas industry for its excellent properties, such as high strength, corrosion resistance, and weldability. It is commonly used to manufacture drill collars, pipes, and other components subjected to extreme conditions such as high pressure and corrosive environments.

Aerospace Industry

Due to its high strength-to-weight ratio, AISI 4137 steel is a popular choice in the aerospace industry for manufacturing aircraft components like landing gear, engine mounts, and structural parts. Its ability to withstand high stress makes it an ideal material for aircraft construction.

Construction Industry

AISI 4137 steel is commonly used in the construction industry for making structural components such as beams, columns, and trusses due to its high strength and durability. It can also be found in bridges, cranes, and other heavy equipment where strength and toughness are crucial.

Manufacturing Industry

Due to its excellent machinability and wear resistance, the manufacturing sector also utilizes AISI 4137 steel for various applications such as machine tools, moulds, and dies. It also produces industrial machinery that requires high strength and impact resistance.

Defense Industry

AISI 4137 steel has been preferred for military equipment due to its exceptional mechanical properties, including high hardness, toughness, and impact resistance. It is commonly used to produce armoured vehicles, tanks, artillery guns, and missiles.

AISI 4137 Corrosion Resistance

AISI 4137 steel is highly corrosion-resistant due to its high chromium content. This type of steel will not corrode easily in environmental conditions such as saltwater or humid atmospheres. Additionally, the molybdenum content of this alloy makes it highly resistant to stress corrosion cracking (SCC).

AISI 4137 Heat Resistance

AISI 4137 steel also has excellent heat resistance due to its high chromium content. At elevated temperatures up to 800°C (1472°F), this alloy will retain its strength and hardness better than other steels with lower chromium levels. However, it should be noted that at higher temperatures above 816°C (1500°F), its strength will begin to decrease rapidly.

AISI 4137 Heat Treatment

AISI 4137 steel must be heat treated before use in order to achieve the desired mechanical properties such as strength and hardness. Common heat treatment processes include annealing (softening), normalizing (stress relieving), quenching (hardening), tempering (stabilizing), and aging (improving strength). The precise process used may depend on the application in which the steel will be used.

AISI 4137 Machining

Due to its good machinability, AISI 4137 can be machined relatively easily using standard techniques such as drilling, tapping, milling, boring, etc. It should be noted that this alloy does have a tendency for work hardening, which means that it may require frequent tool changes during machining operations in order to achieve optimal results. Additionally, cutting speeds should be kept relatively low when working with this material in order to prevent excessive wear on cutting tools or workpieces from overheating due to friction caused by high cutting speeds.


AISI 4137 is an excellent all-purpose low-alloy steel with good strength and toughness properties, along with excellent corrosion resistance and heat resistance, thanks to its high chromium content. Its good machinability makes it suitable for use in many industrial applications, including automotive engineering, oil & gas exploration, agricultural machinery machine tools & general engineering, etc. Heat treatment is required prior to use in order to achieve desired mechanical properties such as strength & hardness & precise process may depend upon the application, although common processes are annealing, normalizing quenching, tempering & aging while cutting speeds should remain relatively low when working with this material because of potential for work hardening & excessive wear on cutting tools or workpieces from friction associated with higher speeds. Overall, AISI 4137 is a great choice for many types of projects where exceptional performance is required!

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