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Alloy steels are designated by AISI four-digit numbers. They are more responsive to mechanical and heat treatments than carbon steels. They comprise different types of steels with compositions which exceed the limitations of B, C, Mn, Mo, Ni, Si, Cr, and Va in the carbon steels.
AISI 4130 alloy steel contains chromium and molybdenum as strengthening agents. It has low carbon content, and can be welded easily. The datasheet below provides further detail.
The chemical composition of AISI 4130 alloy steel is listed in the following table.
||97.03 – 98.22
||0.80 – 1.10
||0.40 – 0.60
||0.280 – 0.330
||0.15 – 0.30
||0.15 – 0.25
|Tensile strength, ultimate
|Tensile strength, yield
|Modulus of elasticity
|Bulk modulus (Typical for steel)
|Shear modulus (Typical for steel)
|Elongation at break (in 50 mm)
|Reduction of area
|Hardness, Knoop (Converted from Brinell hardness)
|Hardness, Rockwell B (Converted from Brinell hardness)
|Hardness, Rockwell C (Converted from Brinell hardness, value below normal HRC range, for comparison purposes only.)
|Hardness, Vickers (Converted from Brinell hardness)
|Machinability (Annealed and cold drawn. Based on 100% machinability for AISI 1212 steel.)
|Thermal conductivity (100°C)
||296 BTU in/hr.ft2. °F
Other designations that are equivalent to AISI 4130 alloy steel include the following;
||UNI 25 CrMo 4
||JIS SCCrM 1
||JIS SCM 2
||B.S. CDS 110
||AFNOR 25 CD 4 (S)
Fabrication and Heat Treatment
Machinability - AISI 4130 steel can be easily machined using conventional methods. However, machining becomes difficult when the hardness of the steel is increased.
Forming of AISI 4130 steel can be performed in the annealed condition.
- Welding of AISI 4130 steel can be performed by all commercial methods.
- Heat Treatment - AISI 4130 steel is heated at 871°C (1600°F) and then quenched in oil. This steel is usually heat-treated at temperatures ranging from 899 to 927°C (1650 to 1700°F).
- Forging of AISI 4130 steel can be performed at 954 to 1204°C (1750 to 2200°F).
- Hot working of AISI 4130 steel can be done at 816 to 1093°C (1500 to 2000°F).
- AISI 4130 steel can be cold worked using conventional methods.
- AISI 4130 steel can be annealed at 843°C (1550°F) followed by air cooling at 482°C (900°F).
- Tempering of AISI 4130 steel can be performed at 399 to 566°C (750 to 1050°F), depending on the desired strength level.
- Hardening of AISI 4130 steel can be done with cold working or heat treatment.
Some of the major applications of AISI 4130 alloy steel are in aircraft engine mounts and welded tubing.
This article was updated on 31st July, 2019