Alloy Steel AISI 6150

General Characteristics

A similar alloy to 5150 with a small, but effective, vanadium addition

Chemical Analysis

C% Mn% P% S% Si% Cr% V% 
0.48/0.53 0.70/0.90 0.040 max 0.040 max 0.20/0.35 0.8/1.1 0.15nom

Principal Design Features

6150 is a fine grained, highly abrasion resistant carbon-chromium alloy steel. Very good shock resistance and toughness are also key properties of this alloy in the heat treated condition.


The alloy is used in the production of forged components of medium and large cross section, requiring high tensile strength and toughness, for automotive engineering and gear and engine construction, such as forged crankshafts, steering knuckles, connecting rods, spindles, intermediate gears, pump and gear shafts.


This alloy would be forged between 2150 and 1600ºF (1175 and 870ºC.) The alloy should be slow cooled after forging or transferred to a furnace around the ‘finishing’ temperature.

Heat Treatment
Annealing: As with 5150 alloy, the microstructure for this alloy to give optimum machinability is one of coarse lamellar pearlite to coarse spheroidite. This might be obtained by austenitizing at 1400ºF (760ºC) followed by an iso anneal at 1250ºF (680ºC.)

Normalizing: A nominal normalizing temperature for this alloy is 1650ºF (900ºC.) This treatment is followed by air cooling.
Hardening: Austenitize at 1550-1625ºF (845-885) and oil quench for small, intricate sections and water quench for large, simple sections.
Tempering: from 1000-1250ºF(540-680ºC) as per required properties.

Machinability: This alloy is readily machined from a coarse pearlite to a coarse spheroidite microstructure.

Weldability: The alloy may be welded but must be preheated and if possible the preheat should be maintained during welding. A post-weld treatment is recommended. Welding should be carried out in the annealed condition, not on hardened and tempered material.


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