AISI / Alloy Steel 8615

Chemical Analysis
C% Carbon
0.13 – 0.18
Mn% Manganese
0.70 – 0.90
P% Phosphorus
0.040 max
S% Sulfur
0.040 max
Si% Silicon
0.20 – 0.35
Ni% Nickel
0.40 – 0.70
Cr% Chromium
0.40 – 0.60
Mo% Molybdenum
0.15 – 0.25

General characteristics of Alloy Steel 8615

Alloy steel 8615 is a case-hardening steel containing nickel, chromium and molybdenum as alloying elements. The alloy shows good strength and toughness properties.


Alloy 8615 is principally a carburizing grade of steel. As such it finds medium-strength applications where high surface hardness and high core toughness are required. The alloy finds uses as forged shafts and bearings in the aerospace and automotive industries.


This alloy is forged at a start temperature of around 2250ºF (1230ºC) and could be forged down to approximately 1700ºF (925ºC.) The alloy is air cooled after forging.

Heat treatment

Annealing: For optimum machinabilty, an as-forged structure is normally sufficient for this grade of alloy steel. If this proves not to be the case then an iso-anneal from around 1650ºF (900ºC) to 1225ºF (660ºC) will improve machinability.

Normalizing: 1700ºF (925ºC) and air cool. This is another method of improving machinability in this grade; normalizing might also be used prior to case hardening.

Hardening: The alloy will be austenitized at around 1550ºF (840ºC) and oil or water quenched depending upon section size and intricacy.

Temper: to desired hardness, using temperatures based on past experience, following water or oil quench.

Machinability: This grade of alloy is readily machined following suitable cooling from forging or subsequent heat treatment.

Weldability: This steel may be welded by normal fusion methods, but prior to carburizing or hardening and tempering.

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