Alloy Steel 4620

General Characteristics

This alloy is a nickel-bearing, case-hardening steel showing good strength and toughness. The alloy may be heat treated to high strength levels.

C% Mn%     P% S% Si% Ni% Mo%
0.17/0.22 0.45/0.65 0.040 max 0.040 max 0.20/0.35 1.65/2.00 0.2/0.3

Principal Design Features

AISI 4620 is a nickel, molybdenum, manganese low alloy steel often used for carburized parts. It has a good combination of strength and toughness and can be heat treated to high strength levels.

The alloy is used in applications where combinations of strength and toughness are required. Forged gears and shafts are manufactured from this alloy.


Machinability is good, especially in the annealed or normalized conditions. In the hardened tempers it becomes increasingly more difficult to machine.


Formability is good in the annealed condition.


4620 may be welded by conventional means prior to heat treatment or carburization.

Heat Treatment

Heat to 1550 F for sufficient time to allow thorough heating and then oil quench. It is desirable to normalize the alloy at 1700 F followed by air cool, before doing the heat treatment and oil quench.


Forge at 2250 F maximum down to 1800 F.

Hot Working

The alloy may be hot worked at 1900 F down to 1500 F.

Cold Working

Cold working of this alloy in the annealed condition can be readily accomplished with conventional methods.


Anneal at 1600 F followed by slow furnace cooling.


Not applicable to this alloy.


Temper at 400 F to 1300 f depending upon strength/hardness desired. Tempering is done following the heat treatment and oil quench. Tempering at 600 F gives a strength of approximately 210 ksi while tempering at 1000 F gives approximately 135 ksi.


This alloy hardens by cold working or heat treatment. See “Heat Treatment” and “Tempering”.

Density: 0.283

Specific Gravity: 7.8

Specific Heat: 0.113

Melting Point: 2590

Thermal Conductivity: 23


MoETensile: 30


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