AISI / Alloy Steel 3150

Chemical Analysis
C% Carbon
0.48 – 0.53
Mn% Manganese
0.70 – 0.90 max
P% Phosphorus
0.040 max
S% Sulfur
0.040 max
Si% Silicon
0.20 – 0.35
Ni% Nickel
1.10 – 1.40
Cr% Chromium
0.70 – 0.90

General characteristics of Alloy Steel 3150

Alloy steel 3150 is a low-alloy steel containing nickel and chromium as alloying elements. The alloy has good hardenability, combined with good strength and toughness properties.


This alloy finds its uses in applications where good strength and toughness are of prime importance. The alloy finds myriad uses in the automotive industry as forged motor and suspension parts, and as landing gear in the aircraft industry. The alloy may also be used for forged fasteners.


This alloy is forged at a start temperature in the region of 2150 – 2200ºF (1175 – 1205ºC) and could be forged down to approximately 1700ºF(925ºC.) The alloy may be slow cooled after forging or transferred to a furnace held at a temperature approximating the forging finishing temperature, soaked then air cooled.

Heat treatment

Annealing: For optimum machinabilty of this alloy, a microstructure consisting of coarse lamellar pearlite to coarse spheroidite is considered to be optimum. Such a structure can be obtained by austenitizing at 1525ºF (830ºC), furnace cooling to 1300ºF (705ºC) then to 1190ºF (645ºC) at 20ºF/hr. An alternative is an iso-anneal at 1225ºF (660ºC)

Normalizing: 1600ºF (870ºC) and air cool.

Hardening:The alloy will be austenitized at around 1500 – 1575ºF (815 – 855ºC) and oil or water quenched depending upon section size and intricacy.

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

Machinability:: This grade of alloy is readily machined following suitable heat treatment.

Weldability:This steel may be welded by normal fusion methods, but prior to hardening and tempering. Pre heat and post heat are recommended.

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