Chemical Analysis
C% Carbon
0.20 – 0.25
Mn% Manganese
0.7 – 0.9
Si% Silicon
0.15 – 0.30
P% Phosphorus
0.035 max
S% Sulfur
0.04 max
Mo% Molybdenum
0.20 – 0.30

General characteristics of Alloy Steel 4023

Alloy steel 4023 is a low-carbon, molybdenum-bearing steel that may be case hardened while showing good core toughness and ductility.


Alloy 4023 finds applications as forged shafts and bushings in such industries as oil and gas, aerospace, and machinery.


The maximum forging temperature for this alloy is approximately 2250ºF (1230ºC). The alloy should preferably not be forged below 1700ºF (925 ºC.)

Heat treatment


Depending upon the complexity of the piece after forging, this alloy may or may not require annealing. It may, in any event, be transferred after forging to a furnace held at around 1550 -1600ºF (845-870 ºC), soaked and slow cooled.


This grade, with its relatively low carbon content, is not normally normalized. If experience proves that in certain cases normalizing prior to, say, carburizing, is beneficial, then a temperature of 1650ºF (900ºC) would be used.

Hardening and tempering

This grade would not be hardened and tempered unless previously surface hardened by, for example, carburizing. In this case hardening and tempering would be carried out on the carburized part, and consultation with a heat treat operator is recommended to ensure optimum properties in both case and core.


Alloy 4023 may be readily machined providing the optimum microstructures are obtained. Again, consultation with a heat treat operation is the best way to ensure that this case obtains.


This grade may be welded by all normal fusion and resistance methods. Pre and post heat as necessary, and weld prior to any surface hardening carried out on material.

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