Alloy Steel 4620

Chemical Analysis
C% Carbon
0.17 – 0.22
Mn% Manganese
0.45 – 0.65 max
P% Phosphorus
0.040 max
S% Sulfur
0.040 max
Si% Silicon
0.20 – 0.35
Ni% Nickel
1.65 – 2.00
Mo% Molybdenum
0.2 – 0.3

General characteristics of Alloy Steel 4620

This alloy is a nickel-bearing, case-hardening steel showing good strength and toughness. The alloy may 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.


The alloy would be forged between 2200 and 1700ºF (1200 and 925ºC.)

Heat treatment

Annealing: This alloy is seldom annealed. Structures of better machinability are developed by normalizing or by isothermal transformation after forging.

Normalizing: 1650-1700ºF (900-930ºC) followed by air cooling.

Carburizing : 1650-1740ºF (900-950ºC) and oil quench.

Hardening: Core: 1560-1620ºF (850-880ºC) and oil quench. Case: 1490-1540ºF (810-840ºC) and oil quench

Tempering : 340-410ºF (170-210ºC.)

Machinability: Best carried out in the normalized condition.

Weldability: The alloy is easily welded, but should be welded prior to case hardening.


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