AISI / Alloy Steel 4017

Chemical Analysis
C% Carbon
0.15 – 0.20
Mn% Manganese
0.70 – 0.90
Si% Silicon
0.20 – 0.35
P% Phosphorus
0.040 max
S% Sulfur
0.040 max
Mo% Molybdenum
0.20 – 0.30

General characteristics of Alloy Steel 4017

This steel is used as a surface-hardening grade. It typifies a range of carbon content found in, say, a 4015 or 4020 type analysis. The molybdenum addition is for prevention of temper brittleness.


This alloy finds uses in the production of forged gears that are subsequently carburized.


The alloy may be forged as high as 2250ºF (1230ºC) and down to a temperature in the region of 1700ºF (925ºC.) The parts will be air cooled following forging.

Heat treatment

Annealing: This grade of steel would rarely be annealed and in fact for optimum machinability an as-forged structure is preferred. A normalizing treatment is recommended in the event that complex forged shapes result in varying structures throughout the parts.

Normalizing: A normalizing treatment may well be necessary during the production of forged gears. A temperature of 1700ºF (925ºC) is recommended, followed by air cooling.

Carburizing:The steel would be carburized at 1650-1740ºF (900-950ºC) followed by water quench for large components of simple shape only, otherwise oil quench.

Hardening:The alloy would be austenitized at a temperature in the region of 1525-1575ºF (830-860ºC) and water quenched in the case of large, simple shapes, otherwise oil quenched.

Tempering: Parts would be tempered at temperatures, based on past experience, that would result in the required mechanical properties.

Machinability: This alloy is readily machined from either an as-forged or normalized structure.

Weldability: The alloy may be readily welded, but only prior to case hardening and subsequent heat treatment.

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